Applicability of Bazant's model to the real world

[pgimeno]

This text addresses how and in what sense Bažant's model, initially stated in and [BZ], and refined in [BV] and [BLGB], with clarifications in [BL] (see below, References), can or can not apply to real world buildings. The author of this text is a layman in the matters in question, yet felt the need for an explanation to exist in view of recent discussions in other threads. Ideally, this analysis should have been done by someone in the structural engineering field who could write such an explanation authoritatively, but apparently noone felt compelled enough to do so, leaving the author the burden to write it despite his lack of qualification. The inaccuracies arising from it may be the result of the lack of author's understanding of engineering principles and practices, and the author welcomes any constructive criticisms aimed at addressing such inaccuracies as long as they are stated with arguments other than incredulity and disbelief, and preferably with sound engineering arguments.

The need for this text arises from the fact that, as stated by another forum member recently, many skeptics of the theory of a government conspiracy misinterpreted Bažant's papers, methods and conclusions, including the author at some point in past, plus there's a new wave of 9/11 deniers who are misinterpreting them for discrediting purposes. So it's important to know how far the scope reaches; where the model can and where it can't be applied to real buildings. Some people, in both sides of the discussion, believe that the models are intended to be applied literally to buildings as a description of what happened. Others, from both sides of the discussion, think that the model is just a theoretical limiting case with no applicability to real buildings. The author has believed both of these things at different points in time, and hopes to prove here that both are incorrect.

A model is an idealized representation of a physical phenomenon in the real world, which can be used to study its behavior and make predictions about it. An example of a model is Newtonian physics. It can describe a wide range of behaviours of our environment and that makes it useful for us.

However, most models, if not all, have limitations. Newtonian physics don't describe the behaviour of objects traveling at a speed close to that of light, for example. That led to the creation of a revised model, special relativity physics, further generalized by general relativity physics. That model still has limitations. And yet, Newtonian physics are still useful as an approximation, as long as we know where the model's limits are and don't ask more of it than what it can give.

When we are confronted with the task of modeling a building collapse, there's one thing that becomes immediately obvious. It's flat impossible to make an accurate model that copes with all possible structural failure causes and modes as they happen in the real world. The reason is simple: the process is too chaotic and even tiny variations in the pressure, inclination, density or other parameters of the structural and non-structural elements can make e.g. a column bend in different angles, with the potential of causing it to impact other columns that would otherwise not be affected by the failure of that column, or to miss them where they would be affected. That's just a very tiny example of how chaos affects a collapse. Even any attempt at a computer simulation of a collapse will be subject to uncertainties in a myriad of tiny parameters such as the exact real-world positioning of a column or girder or the exact distribution of the strength of a welded connection, which will inevitably make the simulation deviate from the real world collapse as it happens, to the point that only a handful of columns, if at all, would show a movement which has any resemblance to the real world. This aspect is clearly demonstrated by the NIST simulations of WTC7 collapse, in which, even if the collapse development exhibits some features of the actual one, the details differ substantially.

To put a bit of order in that chaos, in order to get a workable model which can be rigurously formalized, Bažant made a simplification to his modeling of the WTC collapse: the column impacts would always be axial, regardless of how they would be in a real case.

What is an axial impact:
Axial impact is the impact that is produced when the impacting surface is the base of the column when impacting vertically. Similar to how a billiards cue stick hits the ball.

This brought consequences to his formalization. One of them was that in such a situation, using the parameters for the towers, the collapse progression would happen by first crushing down the bottom part of the building, and then crushing up the top part. This is the infamous crush-down/crush-up sequence which has been in the center of most misunderstandings and criticisms to Bažant's work.

Obviously, these axial impacts between columns would be quite unlikely for many buildings and failure modes. For example, a possible outcome of an impact of a vertical column with an inclined surface is that the column is dislodged rather than bent, depending on surface angle and other factors, resulting in the column acquiring an inclination itself and losing its ability to carry loads, after using probably less energy than a plastic axial deformation would require.

What is a plastic axial deformation:
When a column impacts axially (see above), it behaves much like a spring. Just as springs, it can be compressed, and just as springs, it can recover its shape after the force that caused its deformation ceases. However, if it's compressed too much, it will suffer a plastic deformation, that is, it won't recover its shape anymore. This can't be reproduced in all springs by compressing them, but it can be reproduced in many springs by pulling them and forcing them to expand a lot. Eventually, they will be deformed and will lose the ability to recover their original shape. With columns, the principle is the same and applies to compression as well.

Despite that and other simplifications, the model was still useful to draw conclusions from it. In particular, already in [B 2001] Bažant stated (p.1):

The details of the progression to failure after the decisive initial trigger that sets the upper part of the structure in motion are of course more complicated. The upper part of the structure, for example, tilts as it falls; furthermore, because the structure is a framed tube with floor beams of large spans, the impacted floors may collapse ahead of the tube, thus depriving the tube wall of its lateral support against global buckling. Regardless of these and other details, however, we can make the following two simple and crude estimates of the overload ratio of the columns of the floor just below the critical floor that triggered the catastrophic chain of events.

From there it is immediately obvious that Bažant was perfectly aware that there were important differences between his model and the real behavior since the very beginning. That didn't prevent him from going on drawing a crude estimate from it. Had he modeled crush-up occuring simultaneously with crush-down, that would probably mean a factor of two deviation in some of his results. Yet that wouldn't affect the outcome, as he explained in an addendum of [BZ] (p.370):

Once accurate computer simulations are carried out, various details of the failure mechanism will undoubtedly be found to differ from the simplifying hypotheses made. Errors by a factor of 2 would not be terribly surprising. But that would hardly matter since the analysis in the paper reveals order-of-magnitude differences between the dynamic loads and the structural resistance. Crude order-of-magnitude estimates made easily by pencil suffice in this case to rule out various intuitive theories that were advanced to explain the collapse.

The corollary is that it is possible to draw some conclusions even from an inexact model, just not any conclusions, and we have to be careful about which ones can be extracted and which ones won't match the real world to any sufficient degree of accuracy at all.

This approach is used several times in [BLGB] to make comparisons and extract several consequences. For example, the free fall myth is finally put to rest in some fronts, including videos from the start of the collapse and seismic records. Today that myth seems to be losing some strength, fortunately.

In particular, the comparison with videos requires a whole section dedicated to compensating the model for the tilt that it does not provide, because it assumes that the top falls straight (see p.901, "Analysis of Video-Recorded Motion and Correction for Tilt").

In order to fine-tune a model so that it more closely resembles the real world whenever the parameters being considered can't be solved in the theoretical field, measurements are taken if possible and applied to the model. That is what NIST did when several severity cases were elaborated, of which the most severe one was picked in view of the results. This proceeding, which has been widely used to blame NIST for making up data, is just a standard parameter adjusting practice for the model to fit reality as closely as possible.

That proceeding is indeed described in the [BLGB] conclusions (p.905, emphasis added):

Several of the parameters of the present mathematical model have a large range of uncertainty. However, the solution exhibits small sensitivity to some of them, and [b]the values of others can be fixed on the basis of observations or physical analysis. One and the same mathematical model, with one and the same set of parameters, is shown to be capable of matching all of the observations, including: (1) the video records of the first few seconds of motion of both towers; (2) the seismic records for both towers; (3) the mass and size distributions of the comminuted particles of concrete; (4) the energy requirement for the comminution that occurred; (5) the wide spread of the fine dust around the tower; (6) the loud booms heard during collapse; (7) the fast expansion of dust clouds during collapse; and (8) the dust content of the cloud implied by its size. At the same time, the alternative allegations of some kinds of controlled demolition are shown to be totally out of range of the present mathematical model, even if the full range of parameter uncertainties is considered.

Here's an example of such finetuning also proposed in (from the abstract, p.308, emphasis added):

The parameters are the compaction ratio of a crushed story, the fracture of mass ejected outside the tower perimeter, and the energy dissipation per unit height. The last is the most important, yet the [b]hardest to predict theoretically. It is argued that, using inverse analysis, one could identify these parameters from a precise record of the motion of floors of a collapsing building. Due to a shroud of dust and smoke, the videos of the World Trade Center are only of limited use. It is proposed to obtain such records by monitoring with millisecond accuracy the precise time history of displacements in different modes of building demolitions.

Finally, there have been some claims that the comments in , in particular points 4 ("Can Crush-Up Proceed Simultaneously with Crush Down?", p.917) and 5 ("Why Can Crush-Up Not Begin Later?", p.919) mean a direct application of the crush direction part of the model to the WTC 1 and 2 as if it was what actually happened. That is wrong. That section is dedicated to discussing the theoretical basis of the crush direction part of the model, about which [G 2008] objected, as this excerpt shows (p. 915):

Applying Newton's third law to the collapse of the Twin Towers, it is clear that the downward force imposed on Part B by the upper Part C generates an equal but opposite upward force. It logically follows that if the downward force generated when Part C impacts Part B is destructive, then the equal and opposite upward force generated in accordance with Newton's third law will be destructive. Instead of embracing this basic law of physics, the paper treats Part C as a rigid body during the crush-down phase, then allows Part C to start deforming only at the start of the crush-up phase

Since the author's always been not-so-good for writing closing words, please indulge him in his use of [BLGB] to do it:

These conclusions show the allegations of controlled demolition to be absurd and leave no doubt that the towers failed due to gravity-driven progressive collapse triggered by the effects of fire.


(Thanks to ozeco41 for raising the point that led to writing this text.)


[b]References

[B 2001]: Bažant, Z.P. (2001), Why Did the World Trade Center Collapse? (http://www.civil.northwestern.edu/people/bazant/PDFs/Papers/404.pdf). Siam News, Vol. 34, No. 8, pp. 1 and 3.
[BZ]: Bažant, Z.P.; Zhou, Y. (2002), Why Did the World Trade Center Collapse?—Simple analysis (http://www.civil.northwestern.edu/people/bazant/PDFs/Papers/405.pdf). Journal of Engineering Mechanics ASCE 128 (No. 1) pp. 2-6, with addendum March (No. 3), pp. 369-370. It's an expansion of the former with corrections, appendices and an addendum published later.
[BV]: Bažant, Z.P.; Verdure, M. (2007), Mechanics of Progressive Collapse: Learning from World Trade Center and Building Demolitions (http://www.civil.northwestern.edu/people/bazant/PDFs/Papers/466.pdf). Journal of Engineering Mechanics ASCE 133 (No. 3), pp. 308-319.
[BLGB]: Bažant, Z.P.; Le, J.-L.; Greening, F.R.; Benson, D.B. (2008), What did and did not cause collapse of World Trade Center twin towers in New York (http://www.civil.northwestern.edu/people/bazant/PDFs/Papers/476%20WTC%20collapse.pdf). Journal of Engineering Mechanics ASCE 134 (No. 10), pp. 892-906.
[BL]: Bažant, Z.P.; Le, J.-L. (2008), Closure to "Mechanics of Progressive Collapse: Learning from World Trade Center and Building Demolitions" by Zdeněk P. Bažant and Mathieu Verdure (http://www.civil.northwestern.edu/people/bazant/PDFs/Papers/D25.pdf). Journal of Engineering Mechanics ASCE 134 (No. 10), pp. 917-923.
[G 2008]: Gourley, J.R. (2008), Discussion of "Mechanics of Progressive Collapse: Learning from World Trade Center and Building Demolitions" by Zdeněk P. Bažant and Mathieu Verdure (http://www.civil.northwestern.edu/people/bazant/PDFs/Papers/D25.pdf). Journal of Engineering Mechanics ASCE 134 (No. 10), pp. 915-916. It's the discussion which is followed up by the above closure. The PDF file in which both appear is the same.

[femr2]

the author welcomes any constructive criticisms aimed at addressing such inaccuracies as long as they are stated with arguments other than incredulity and disbelief, and preferably with sound engineering arguments.

Firstly, it's good to see additional attempts at clarifying scope.

A couple of points, which I hope you will not take as nit-picks...

there's a new wave of 9/11 deniers who are misinterpreting them for discrediting purposes
9/11 deniers ? Strange turn of phrase. I've commented that there are folk who apply the model too literally, but the purpose is clarity, not *discrediting purposes*.

Since the author's always been not-so-good for writing closing words, please indulge him in his use of [BLGB] to do it:

These conclusions show the allegations of controlled demolition to be absurd and leave no doubt that the towers failed due to gravity-driven progressive collapse triggered by the effects of fire.
Ah. Not a great closure in my opinion.

The model does not include initiation, and so does not deal with what caused failure.

It proves that it is possible, post initiation, for gravity to drive progressive collapse. (ROOSD is imo a good description of that process)

It does not disprove.

To illustrate, and to illustrate only... If *evidence* arose tomorrow, which *proved* that *space aliens* *made it happen on purpose*, then the scope of the model does not change at all.

The conclusion steps outside the bounds of model applicability.

[Major_Tom]

Here is an excellent example of somebody applying the concept of crush down then crush up to the description of a 3-D building:



This is not the only factor, but it too is partially correct.

Think of it in terms of impulse -- the total change of momentum at a particular impact. Impulse is equal and opposite, by conservation of momentum. Impulse is equal to F delta-T (force times the time over which the force is applied), or M delta-V (the raw change of momentum in its familiar definition P = m V).

When we look at the "upper block," it's delta-V is smaller than the delta-V experienced by the newly broken part of the lower block. As you say, the upper block decelerates by an average 1/3 g, while the lower block accelerates by an average 2/3 g. This is because the participating part of the lower block masses less than the participating part of the upper block -- it really is the compacted mass and upper block versus a small number of floors at a time, not the entire lower block.

The reason only part of the lower block participates at any given time is because the lower block is still a mostly intact sparse structure of braced columns. When it's hit, the columns lose bracing, get loaded eccentrically, shear their welds and bolts, and in some cases are totally overwhelmed and fracture entirely. These pieces break at a stress much too low to actually support the descending mass. This also has nothing to do with the strength of the perfectly intact building -- the descending rubble heap isn't contacting the lower structure at its strongest points, and it's introducing brand new failure modes, so the effective opposing strength of the lower structure is far lower than its ideal carrying capacity. Furthermore, where the lower structure does resist at or near its ideal strength, it can only do so for a very brief delta-T -- until reaching its failure strain, which takes only about ten milliseconds at the speeds of collapse -- and this is not enough to amount to all that much total impulse.

The upper chunk, in contrast, is cushioned by a thick layer of rubble. This is compacted about as far as it can, thus it doesn't have those complex failure modes and it doesn't suffer much more "damage" even at much higher stresses. So the rubble pile remains, and the lower structure gives way. This is for the same reason you don't sink into the ground, even though you can push your finger easily through a cupful of soil.

The "upper block," what remains of it, rides on top of this cushion of debris. It is supported pretty well. It also only decelerates at that lower rate, thanks to the much greater inertia of the upper block + debris. So the only real force it suffers is the inertial force, i.e. its own self-weight times its deceleration, again about 1/3 g. It can be expected to survive this deceleration. It's only when the rubble pile has nowhere else to go and the upper block has to suddenly stop, dissipating all of its momentum in mere milliseconds, that it totally fails.

Again, this is slightly idealized, but you get the point. Unless you're a Truther.

He calls this discription based on a literal interpretation of the 1-D stick model introduced in BV "slightly idealized".

He clearly believes in the magic zone B rubble layer and the upper block that rides the rubble to earth like the Virgin Mother descending from the clouds.


Honestly, pgimeno, is not R Mackey taking the 1-D concept of crush down, then crush up quite literally in his description? He seriously believes that this upper block exists, just like Bazant.

[pgimeno]

9/11 deniers ? Strange turn of phrase. I've commented that there are folk who apply the model too literally, but the purpose is clarity, not *discrediting purposes*.

See below your post.

Ah. Not a great closure in my opinion.

The model does not include initiation, and so does not deal with what caused failure.

Ah, but that's because you're looking for the philosopher's stone, that thing which will make you rich and famous once you find any evidence of it and that you keep looking for because you know it must exist somewhere.

That paragraph addresses the theories that were into fashion by then. But belief currents wear off too, e.g. nobody is pushing for thermate or freefall of the towers these days.

[beachnut]

It is cool Bazant and company are able to do on a napkin what 911 truth can't do at all given all the answers and 8 years!

Funny, 911 truth CD delusion cult members attack Bazant's model and fail to understand their attacks prove they don't understand models, engineering, and more. Where do their idiotic CD delusions come from?

Bazant's model is like a trap to catch people with idiotic claims as they attack and comment on Bazant's work to expose their incompetence and ignorance. Why do they not have a clue. Kind of makes it clear they are not engineers, only a tiny fraction of engineers are prey to delusions like the lies 911 truth pushes.

What level do you have to be at to understand without effort why the WTC Towers were doomed by impacts 7 to 11 times greater than design, and fires set with 66,000 pounds of accelerant!

http://www.nae.edu/Publications/TheBridge/Archives/V32-1EngineeringandHomelandSecurity/ReflectionsontheWorldTradeCenter.aspx Robertson, the first expert on the WTC towers structure

The answer is easy, and can be found with google! Amazing Google can be used to support reality if you are capable of critical thinking and logical skills to weed out the lies, hearsay and delusions of 911 truth. Robertson calls the CD delusions nonsense.

Google "lead structural engineer reflects, fall of the World Trade Center towers", and you find someone uniquely qualified to say the WTC towers fell due to impacts and fire. And he is proved correct by many independent studies, and he calls 911 truth claims nonsense. (http://www.nae.edu/Publications/TheBridge/Archives/V32-1EngineeringandHomelandSecurity/ReflectionsontheWorldTradeCenter.aspx)

How many 911 truth failed idea believers will show up to attack Bazant and try to twist things so they can back in their favorite fantasy on 911?

People should not attack Bazant's work, they need to do what it takes to complete their own work and see if it floats; publish it in a real journal. 911 truth can't do that, they can only attack NIST, Bazant's, and if they could do research I suppose they would attack the hundreds of other studies, papers and research showing impacts and fires did it. 911 truth are challenged researchers who can't find evidence or other work and understand those efforts to understand their claims are idiotic delusions.

How many loyal 911 truth cult members will show up to battle Bazant and fail faster than free-fall?

[bill smith]

Readers whould check out what Major Tom has to say in the link that pgimeno has distanced himself from. Is Bazant worthwhile ? Was Bazant ever worthwhile really ?

http://forums.randi.org/showpost.php?p=6274283&postcount=83

[ozeco41]

...The need for this text arises from the fact that, as stated by another forum member recently, many skeptics of the theory of a government conspiracy misinterpreted Bažant's papers, methods and conclusions, including the author at some point in past, plus there's a new wave of 9/11 deniers who are misinterpreting them for discrediting purposes. So it's important to know how far the scope reaches; where the model can and where it can't be applied to real buildings. Some people, in both sides of the discussion, believe that the models are intended to be applied literally to buildings as a description of what happened. Others, from both sides of the discussion, think that the model is just a theoretical limiting case with no applicability to real buildings. The author has believed both of these things at different points in time, and hopes to prove here that both are incorrect... A good summary. It states the extreme positions clearly and goes to one aspect of Bazant's work has concerned me from the start of my 9/11 involvement mid 2007.

I have no doubt as to his overall validity - the global position that there was energy to spare to ensure the global collapse. And no problem if Bazant's claims are taken no further than that global position.

But time and again I have seen people from both sides take it too far when applied to 9/11. And, sadly from my perspective, little attempt to put clear scope boundaries about either what Bazant says OR how it can actually apply to WTC 9/11.

Here is the core of my concerns:
..To put a bit of order in that chaos, in order to get a workable model which can be rigurously formalized, Bažant made a simplification to his modeling of the WTC collapse: the column impacts would always be axial, regardless of how they would be in a real case...
So "the column impacts would always be axial"?? Could anything be further from what actually happened with the twin towers on 9/11?

Remember we are talking about the global collapse - the top block has started to fall - a point most people seem comfortable with.

But, if the top block is falling, what does that say about "end for end axial contact" of top block columns and lower tower columns.

The case of the outer tube columns is relatively easy to see - by the time global collapse was progressing the bulk of falling mass was falling inside the outer tube - shearing floor connectors. The outer tube columns falling away after the falling mass has passed by several floors. Those columns were not buckled and fell aside as sheets of varying sizes - apparently and naturally failing mostly at the construction joints.

So what "axial load transfer" are all these papers talking of when they miss this point? The only axial loads on the outer columns being some friction of falling mass plus the force resulting from the shearing impacts of successive floors. At least one order of magnitude lower forces than anything likely to cause buckling.

There are questions to answer as to how the top block ended up inside the outer tube of the lower tower. And whether or not its own columns were still attached at that stage. So what price discussion of "crush up" unless people address the fundamental of how and in what condition the top block got itself inside the outer tube of the lower tower.

The case of "top block core on lower tower core" raises similar but more complicated questions which I will leave for later explanation.

So those are a couple of points which go to my concerns about people taking Bazant too far outside his base assumptions and trying to too literally apply Bazant's "crush down/crush up" to an actual situation where those concepts are at best a strained fit. that is unless we define what actual mechanisms we are supposed to be discussing.

...(Thanks to ozeco41 for raising the point that led to writing this text.)..
..thank you for the acknowledgement and the comprehensive post.

Lets see where discussion leads.

[ozeco41]

...The model does not include initiation, and so does not deal with what caused failure.

It proves that it is possible, post initiation, for gravity to drive progressive collapse... Good points.

In extended discussion on another forum I tried to "nail down" CTs and truthers to which stage of collapse they were describing.

For purposes of my own explanation the two critical stages were:

1) the progressive deterioration leading to the cascading failure of the "initial collapse"; AND
2) The global collapse.
..with the line between the two being the brief period when the top block first started its descent.

At that point the columns of the lower tower were carrying less load than the full weight of the top block AND there was little if any axial contact of top block columns on lower tower columns AND such axial contact as may have existed was in a process of rapid buckling failure of said columns.

Which gives a reliably defined boundary between the two stages.

Then your point restated - the "initial collapse" caused failure - once that initial collapse started the top block descending then the "global collapse" was inevitable. This latter point as claimed by NIST, demonstrated in a limiting case analysis by Bazant AND independently determined by many others of us using our own variations of explnation.

[femr2]

Which gives a reliably defined boundary between the two stages.

The more relvant point in the context of this thread is the erronious closure...

These conclusions show the allegations of controlled demolition to be absurd and leave no doubt that the towers failed due to gravity-driven progressive collapse triggered by the effects of fire.


As I said, the model does not include initiation, and so does not deal with what caused initial failure.

It does prove that, if the simplified initial state of the model is attained, post initiation, that it is possible for gravity alone to drive global collapse. (with a few caveats)


It does not disprove.


The conclusion steps outside the bounds of model applicability.


(Clarification of bounds and scope being the entire point of this thread, this point should be made clear, and acknowledged by all.)

[ozeco41]

The more relvant point in the context of this thread is the erronious closure...

As I said, the model does not include initiation, and so does not deal with what caused initial failure.

It does prove that, if the simplified initial state of the model is attained, post initiation, that it is possible for gravity alone to drive global collapse. (with a few caveats).. Agreed all three points - sorry if it was not explicit enough in my previous.
...The conclusion steps outside the bounds of model applicability.
......it sure does.

[pgimeno]

So "the column impacts would always be axial"?? Could anything be further from what actually happened with the twin towers on 9/11?

Remember we are talking about the global collapse - the top block has started to fall - a point most people seem comfortable with.

No, we're not talking about the global collapse. We are talking about a mathematical model of the collapse which is an approximation of it. That in itself makes it irrelevant how the impacts actually happened, just as the fact that greater than light speed is not contemplated or prevented by Newtonian physics.

Despite the differences between model's behavior and real behavior which affects things like the way the columns impacted, the model still has many resemblances to real world and it can be used for that purpose, just not e.g. for how the column impacts actually happened, just as Newtonian physics can still be used to obtain very good approximations of how objects behave, just not for cases where the speed approaches light speed.

So what "axial load transfer" are all these papers talking of when they miss this point?

I think it's you who is missing the point. The point is that it doesn't matter - the differences in the impact behavior can still make little differences in many of the results. However, actual impact behavior is very difficult to model as there's a cloud of uncertainty surrounding it, while axial impact behavior has been modeled successfully.

Granted, there's still the concern that the results making big differences and the ones making little differences need to be separated. In that sense, [BLGB] is a good reference as it compares the model against several real-world parameters.

[metamars]

It does prove that, if the simplified initial state of the model is attained, post initiation, that it is possible for gravity alone to drive global collapse. (with a few caveats)


Considering that Bazant Zhou postulates an axial impact - in their theory, not in the real world collapse - you'd think that they would have referred to the literature on axial impacts which existed well before their paper was written. I'm referring to a body of technical literature, some (probably most) of which has been experimentally tested.

I still don't know if using a more realistic, purely elastic theory, for an idealized, axial impact would result in the elastic limit being exceeded, or not. I tend to think so, based on calculations I've done, but I'm still not sure, since the situations weren't good enough matches to the BZ scenario. (As for absurdities of the BZ model which predispose it towards collapse, you can search my other writings on the subject. They mixed assumptions which both favored collapse, as well as favored survival, and made no attempt to quantify the relative implications of each. Thus, their paper is illogical! It proves nothing even remotely related to a real world collapse, because it can prove nothing. Kind of interesting that self-styled debunkers would fail to notice this, huh?)

However, an axial impact on a steel rod which exceeds the elastic limit doesn't automatically result in failure. Depending on the details of the problem, you could arrest the striking weight's motion, with energy being dissipated in plastic deformation. (This is what Gordon Ross attempted to calculate, though without benefit of the knowledge of the literature which already existed. Gordon was quite open to knowledgeable input and criticism, contrary to what some of the people who have smeared him have implied. I know this from personal communication. Unfortunately, I hadn't yet run across the body of knowledge about elastic/plastic deformations which follow axial impact, when we had these communications.) The plastic deformation wave travels at about 1/10th the speed of an elastic wave, in steel.

Ari-Gur, to name one researcher in elastic/plastic collision theory, has a relatively simple theory for this, which he has tested, and got fairly good experimental confirmation of his theory.

To date, neither debunkers nor ae911truth have bothered applying the most relevant, and experimentally tested theory, to the BZ scenario (actually, a modified BZ scenario where the entire column lines would be assumed to be able to transmit both elastic energy, and undergo plastic deformation in the manner observed in experiments).

I really don't expect much of debunkers, but I had, at one time, expected the engineering contigent at ae911truth to rise to this relatively modest challenge.

Shame on both the debunkers and ae911truth.

If anybody ever does this, it'll probably be an open-minded member of the911forum.freeforums.org, not ae911truth or a serial debunker member of JREF.

The whole Bazant Zhou thing is a bit of a red herring, even at best. It's main value is probably in showing how irrational* NIST and debunkers are, and subsequently how, um, "un-engineering like" ae911truth has proven to be. (I wanted to write "lazy", but as shutting down ae911truth's forum was - presumably - Gage's doing, and quite a while ago, it's certainly possible that ae911truth's engineering contingent would have attempted this in the last few years, if they had been told about this. So, whoever shut down their forum, shame on you, too.)

If you just gently rested the top block on the bottom block, but 'off-center' (columns resting on floors, except when outside the footprint of the base), then I expect the building to collapse. You wouldn't even need to drop it by one storey height.

What such a collapse would look like.... I don't know....


* And perhaps dishonest.

[femr2]

If anybody ever does this, it'll probably be an open-minded member of the911forum.freeforums.org, not ae911truth or a serial debunker member of JREF.
There has been much discussion of the model there of course, but the main problem, as far as I am aware, is the omission of the form of the force function used in B&L.

I'd like to see the function provided, and the model implemented with those handy computer things, such that it is possible to:

a) regenerate and replicate the published results
b) test parameter sensitivity

[beachnut]

There has been much discussion of the model there of course, but the main problem, as far as I am aware, is the omission of the form of the force function used in B&L.

I'd like to see the function provided, and the model implemented with those handy computer things, such that it is possible to:

a) regenerate and replicate the published results
b) test parameter sensitivity
Contact Bazant. You and metamars are exposing you have zero engineering skills and don't understand models.

You and metamars as truthers should publish your fantastic engineering work and prove to all the debunkers how it is. What is stopping you? Engineering degrees and skills? Publish your claims and prove you got something. Because to this engineer you guys post nonsense based on ignorance and your need to have a delusion of CD. When you make silly comments on Bazant's model you expose your lack of knowledge on models. This is a trap for you guys with delusions on 911 - stop being so easy.

I really don't expect much of debunkers, but I had, at one time, expected the engineering contigent at ae911truth to rise to this relatively modest challenge.
You debunk yourself, and there is no rational engineering contingent at ae911truth. They can't support the lies of Gage and your fantasy about 911. You are a debunker when you expose your lack of knowledge and attack a model. Make your own model, publish it. You are very good at posting nonsense and making it look technical; are you an engineer, or what? Where did you get the skill to makeup posts that have the facade of being technical? That is a skill you have; I have marveled on the massive expanse of posts you have made over the years. They go on and on, and you have made zero progress to push your version of 911. But you have produced a lot of mush. Send a letter to a real Journal with your critique of Bazant! Take some action, what if you are right!? Do something to make up for 8 years of failure and delusions. Heiwa did it! You can do it!

[pgimeno]

I still don't know if using a more realistic, purely elastic theory, for an idealized, axial impact would result in the elastic limit being exceeded, or not. I tend to think so, based on calculations I've done, but I'm still not sure, since the situations weren't good enough matches to the BZ scenario. (As for absurdities of the BZ model which predispose it towards collapse, you can search my other writings on the subject. They mixed assumptions which both favored collapse, as well as favored survival, and made no attempt to quantify the relative implications of each. Thus, their paper is illogical! It proves nothing even remotely related to a real world collapse, because it can prove nothing. Kind of interesting that self-styled debunkers would fail to notice this, huh?)

Dude, even Björkman got a criticism of Bazant's work published in the JoEM, and I think even you will agree with me in that it had no merit at all. Why don't you publish a good, well-referenced criticism in such a publication? I'm eager to see a well reasoned discussion of his paper rather than the farces that have been seen so far.

To date, neither debunkers nor ae911truth have bothered applying the most relevant, and experimentally tested theory, to the BZ scenario (actually, a modified BZ scenario where the entire column lines would be assumed to be able to transmit both elastic energy, and undergo plastic deformation in the manner observed in experiments).

I really don't expect much of debunkers, but I had, at one time, expected the engineering contigent at ae911truth to rise to this relatively modest challenge.

Shame on both the debunkers and ae911truth.

ae911truth is a well-defined collective, and that you expected more from them, who have no single paper about their ideas published in any real journal but whose founder has an agenda of attracting gullible people with flawed arguments, speaks lots.

Why don't you take your own challenge, as I took this one when publishing the above text when noone else jumped into it, instead of stating your opinions and waiting for someone else to do the job?

Besides, you may think that the matches between theoretical and real data in [BLGB] are just luck, but the burden of proof lies upon whoever thinks that. No shame for those who admit it as real. I'd rather say shame on those of ae911truth that don't believe it and are dedicated to smearing it, and shame on you for not dedicating to prove what you are openly claiming here.

The whole Bazant Zhou thing is a bit of a red herring, even at best. It's main value is probably in showing how irrational* [* And perhaps dishonest] NIST and debunkers are, and subsequently how, um, "un-engineering like" ae911truth has proven to be.

Can you please explain

1. what makes NIST irrational (*and perhaps dishonest) in this respect, and
2. what makes the collective you call "debunkers" irrational (*and perhaps dishonest)?

That part of your post, however, is really interesting. What you are saying here is basically the same that most critics of ae911truth say, and indeed you are being a critic of ae911truth here. The best they have is Chandler's and Szamboti's flawed analyses, none of which bears a critical examination and none's been published in a real journal.

[Major_Tom]

The Bazant Zhao argument of 12 ft freefall before the first collision has been a total red herring.

We want to know what initiated collapse, not whether the building would bounce after a 12 ft fall.

Metamars writes in post #12: "If you just gently rested the top block on the bottom block, but 'off-center' (columns resting on floors, except when outside the footprint of the base), then I expect the building to collapse. You wouldn't even need to drop it by one storey height. "

Exactly. If this is true why would anyone argue for a big bounce after 12 ft? It's an argument for suckers.


The demo would initiate collapse and once those columns are displaced is there any reason to expect the building to fare well?

I don't care if buildings were designed to survive a good bounce. I care about what initiated collapse.

It's a total red herring as both Bazant and the NIST skip over the real issue of the initial column failure sequence.

[Major_Tom]

Pgimeno, you seem to be very impressed by the publication process. We are debating here, now, on this forum.

If you cannot tell the difference between a 1-D stick model and the real towers here, now, how will it help you if you see our arguments in print?

[Major_Tom]

Pgimeno, many of us have been critics of the scholars and AE911T for a long time. Quite vocally to the point of being kicked out of their forums.

The best research I have seen has been done by independent researchers not associated with either group.

In my opinion the standard debunker vs AE911T back and forth arguments have been mostly fake. Fake arguments and equally fake counter-arguments.

Tweedle-dee vs Tweedle-dum, while the better independent researchers go largely ignored in all the smoke and mirrors.

[TexasJack]

The best research I have seen has been done by independent researchers not associated with either group.


You mean by independent research those with unpublished work and a degree from Google University.

[pgimeno]

I don't care if buildings were designed to survive a good bounce. I care about what initiated collapse.

That's fine, but speak for yourself. Dedicating efforts to the study of collapse progression instead of your object of interest doesn't make the resulting engineering studies such as Bazant's a "red herring", no matter how much you try to smear them. That's quite an egocentric point of view. Along time, people have studied what has concerned them instead of what has concerned you. Face it.

Pgimeno, you seem to be very impressed by the publication process. We are debating here, now.

No, I'm confident of it as a guarantee of competence, of which you have shown quite little here so far.

Plus, that tends to be the excuse of those who know they can't get published.

But my point stands. Even Björkman's incompetence was exposed to the engineering world in an engineering journal. If you have a good point, you should have no problem to be published there as Björkman was. I just hope that, in case you don't even pass even the most basic threshold to get published there, you won't come crying about "the establishment" or a standard excuse like that.

[beachnut]

Pgimeno, many of us have been critics of the scholars and AE911T for a long time. Quite vocally to the point of being kicked out of their forums.

...
What independent researchers? Are they scenics or engineers? Are they better than Bazant? You have conspiracy theories on your conspiracy theories. Smoke and mirrors? Is that your work?

It is funny how you are stuck on NIST.

You are kicked out of forums because you post BS, which you think is engineering. It is funny as ae are do nothing cult members with thermite rot on the brain, it is amazing they can see your work as nonsense. It is ironic your BS CD delusion is kicked out from people with the same delusions and worse. Are you making up another CT?

If you have problems with Bazant publish them! It will be interesting to see the adjectives of nonsense and delusional used in a real journal when your junk is evaluated. Heiwa did it why can't you! You can always make up another CT after it goes bad.

[femr2]

This text addresses how and in what sense Bažant's model, initially stated in [B 2001] and [BZ], and refined in [BV] and [BLGB], with clarifications in [BL] (see below, References), can or can not apply to real world buildings.

The author welcomes any constructive criticisms aimed at addressing such inaccuracies as long as they are stated with arguments other than incredulity and disbelief

Since the author's always been not-so-good for writing closing words, please indulge him in his use of [BLGB] to do it:

These conclusions show the allegations of controlled demolition to be absurd and leave no doubt that the towers failed due to gravity-driven progressive collapse triggered by the effects of fire.


I highlighted the inapplicability of your quoted closing remarks in the very first response to your OP.

Namely that...

The conclusion steps outside the bounds of model applicability.

Bearing in mind the specific purpose of your thread, I assume you are going to acknowledge this point shortly.

Not only is it a perfect example of the way that the model is used incorrectly, but it is a quote from the model authors themselves.

I also suggest you request that further posts from ALL members directly address the thread topic at all times.

[beachnut]

Since the author's always been not-so-good for writing closing words, please indulge him in his use of [BLGB] to do it:
These conclusions show the allegations of controlled demolition to be absurd and leave no doubt that the towers failed due to gravity-driven progressive collapse triggered by the effects of fire.

Bazant knows it was not controlled demolition, as do 99.99 percent of all engineers. Nice to see it published so 911 truth has some move evidence they can ignore.

It was also cool the OP is referenced. 911 truth pseudo-wannabe-engineers never use source or references for their made up nonsense which they use for science and evidence.

When you find 911 truth work referenced and sources, you can follow the references and sources to debunk the work. It is classic 911 truth. 911 truth cult members can't comprehend the closing statement is based on evidence, not failed paranoid conspiracy theories based on lies and hearsay. They don't do evidence, or understand Bazant does.

[Furcifer]

We want to know what initiated collapse, not whether the building would bounce after a 12 ft fall.


Fire. :rolleyes:

[ozeco41]

No, we're not talking about the global collapse. We are talking about a mathematical model of the collapse which is an approximation of it. .....I think it's you who is missing the point. The point is that it doesn't matter - the differences in the impact behavior can still make little differences in many of the results. However, actual impact behavior is very difficult to model as there's a cloud of uncertainty surrounding it, while axial impact behavior has been modeled successfully....
Point taken that I need to be very explicit.

If we are talking about the Bazant model as a generic model then the model is valid as far as it goes.

BUT if we apply the generic model to a specific situation where the assumptions of the generic model are not valid - then the model ceases to be correct and may introduce errors which may be significant.

So you clarify that "we're not talking about the global collapse [of WTC1 and WTC2]"

Whereas I was attempting to relate the Bazant generic model to the specifics of the WTC twin towers global collapse stage.

So continue discussion of Bazant's model without referring to WTC global collapse and I have no concern.

My concern arises only when Bazant's model is taken into areas of analysis of WTC collapse where it does not fit. Where his assumptions, especially the assumptions about axial contact, are significant.

So your next comment "We are talking about a mathematical model of the [global] collapse which is an approximation of it."

So, like me you are relating to WTC global collapse. So your statement hinges on what you mean by "approximation"? I hold to my several times repeated statement. I have no doubt that Bazant was "globally" correct - there was more than enough energy to ensure complete collapse once it was initiated. I question the validity if the concept is taken to further detail given Bazant's assumption of axial column contacts in his model and the near absence of such contacts in the WTC global collapse.

[femr2]

PMy concern arises only when Bazant's model is taken into areas of analysis of WTC collapse where it does not fit. Where his assumptions, especially the assumptions about axial contact, are significant.
This reminds me of discussions I've had with David Benson, which arose through discussion of the roughly linear rate ejecta streams equating to the position of the primary *crush fronts*.

The velocity of the WTC 1 south-side crush front was found to reach fairly constant rate after about 5 seconds, reaching ground in roughly 14.5 seconds.

David's input to the discussion was that such details matched outputs from the model.

This is a concern imo.

The crush fronts are essentially the result of *pancaking*, with ROOSD being a more detailed description.

Why do the outputs from the model involving axial column impacts match behaviour, velocity profile and global descent time of a completely different mechanism ?

(Especially when it is clear that actual column destruction was significantly slower in propogation rate than ROOSD)

That is why, as indicated earlier, it would be useful if the form of the force function was provided, such that the model results can be replicated and parameter sensitivity tested.

[pgimeno]

I highlighted the inapplicability of your quoted closing remarks in the very first response to your OP.

Namely that...

The conclusion steps outside the bounds of model applicability.

Bearing in mind the specific purpose of your thread, I assume you are going to acknowledge this point shortly.


Rigorously speaking, that's true.

Certainly, Bazant doesn't deal with collapse initiation, where there is certainly room for a deliberate action against the towers. However, the amount of demolition theory believers that sustain that point of view is so low that they can be readily dismissed. Thus Bazant's comment as quoted is accurate in its context (the clear intention of dismissing claims on the merit of floor-by-floor explosive demolition) even if not scalpel-accurate. I must say, that making that much emphasis in that distinction does not seem neutral to me at all, but the contrary. It looks to me as giving last-term excuses for those who can be convinced by Bazant's arguments in order to sustain the unproven, purely faith-based deliberate destruction of the towers. It's precisely the lack of any kind of support from either evidence or rational thought (but I must put emphasis on lack of evidence), that should lead to dismiss it without giving it any serious consideration when objectively evaluated. It pertains to the realm of speculation and it's sad that faith is the only motivation for the search of evidence in that respect from people that mostly seem otherwise quite rational.

[bill smith]

If you want to see just how inapplicable Bazant is to the 9/11 paradigm just think about his 'upper block'.

We know that 15% or less of the columns, both core and perimeter that connected upper and lower blocks were destroyed by the plane crash. So 85% or more were intact.

So what is all this about an ' upper block ' ?

We should be talking about how those 85% apparently simultaneously ceased to exist as columns.

[femr2]

The conclusion steps outside the bounds of model applicability.
Rigorously speaking, that's true.
Agreed.

Response to the rest of your post is over at the911forum...
http://the911forum.freeforums.org/post12226.html?hilit=#p12226

[pgimeno]

Point taken that I need to be very explicit.

Yes, this is an area where misunderstandings have been and have the risk to be common.

If we are talking about the Bazant model as a generic model then the model is valid as far as it goes.

BUT if we apply the generic model to a specific situation where the assumptions of the generic model are not valid - then the model ceases to be correct and may introduce errors which may be significant.

So far, so good. That's precisely why I use this sentence:

The corollary is that it is possible to draw some conclusions even from an inexact model, just not any conclusions, and we have to be careful about which ones can be extracted and which ones won't match the real world to any sufficient degree of accuracy at all.



So your statement hinges on what you mean by "approximation"? I hold to my several times repeated statement. I have no doubt that Bazant was "globally" correct - there was more than enough energy to ensure complete collapse once it was initiated. I question the validity if the concept is taken to further detail given Bazant's assumption of axial column contacts in his model and the near absence of such contacts in the WTC global collapse.

That's a valid point that I certainly admit to have kind of handwaved because of my lack of knowledge in the field. I have a strong feeling that some of the results will apply equally to both the real case and the model, but I can't tell you precisely which ones. That's not only my sensation, though. In another forum someone made a comment from one of my sentences:

Had he modeled crush-up occuring simultaneously with crush-down, that would probably mean a factor of two deviation in some of his results.

Those results, specifically, would be count of number of members failed and the associated energy in deformation and failure until crush-up concludes. Displacement of the roofline would be considerably greater over the mixed crush interval, not necessarily a factor of two. There is strong reason to believe most other dynamic quantities of interest would not be affected much, at the level of detail of the model.

(Emphasis in original).

Wish I could be any more precise. Sorry, I can't. I have ventured an assumption regarding e.g. this quote from [BV] (p.312):

Detailed finite element analysis simulating plasticity and break-up of all columns and beams, and the flight and collisions of broken pieces, would be extremely difficult, as well as unsuited for extracting the basic general trends. Thus it appears reasonable to make four simplifying hypotheses: [...]


I assume that he knows how the simplifications he makes affect the obtained results and that he knows that they won't have a very significant effect on the results he intends to obtain.

But then, I guess I would need to be an engineer to be able to actually make an evaluation about that.

[ergo]

The Bazant Zhao argument of 12 ft freefall before the first collision has been a total red herring.

We want to know what initiated collapse, not whether the building would bounce after a 12 ft fall.

Metamars writes in post #12: "If you just gently rested the top block on the bottom block, but 'off-center' (columns resting on floors, except when outside the footprint of the base), then I expect the building to collapse. You wouldn't even need to drop it by one storey height. "

Exactly. If this is true why would anyone argue for a big bounce after 12 ft? It's an argument for suckers.

The demo would initiate collapse and once those columns are displaced is there any reason to expect the building to fare well?


If I may be allowed to comment in this more technical discussion... Showing that a jolt or bounce back accompanies any collision demonstrates that the lower portion is sufficiently providing resistance, as would be predicted. Which in turn shows that crush down would not occur first.

As for "gently resting the upper block" off-centre on the lower, how and why would two floors of off-centre columns precipitate a global collapse of the entire rest of a building whose columns are intact? This makes no sense. And if you're further suggesting that it would be a crush down, this makes even less sense.

[pgimeno]

Agreed.

Response to the rest of your post is over at the911forum...
http://the911forum.freeforums.org/post12226.html?hilit=#p12226

Despite this clear sentence I added to the beginning and end?

It is taking quite a good amount of time to follow one forum and I didn't have any plans to follow two.

[...]

As a final word, as outlined above, I will probably not comment much or at all to any responses.
femr2, the titles of your videos speak lots, and your attitude does too. I have already discussed some personal aspects of this with you (http://forums.randi.org/showthread.php?p=6222828#post6222828), so I won't extend in that direction.

[metamars]

There has been much discussion of the model there of course, but the main problem, as far as I am aware, is the omission of the form of the force function used in B&L.

I'd like to see the function provided, and the model implemented with those handy computer things, such that it is possible to:

a) regenerate and replicate the published results
b) test parameter sensitivity

I was referring specifically to BZ.

Subsequent papers looked more relevant to a real collapse. (Which is a good thing since, as noted, BZ is illogical, and can't prove anything about a real world collapse.) Though I vaguely recall deriving an unbelievable prediction from one of them (I think it was BV; I may have posted results at physorg), I'm not really competent to analyze the 'definitive' BLGB, as it involved theorizing of a sort that I'm not familiar with. (I can't remember the term, but it wasn't theories based on first principles, or derivations like one makes in a dynamics class, but rather a theory, such as hooke's law, that follows from observation, and has some sort of statistical validity.)

I don't trust such theorizing, because in the case of the WTC, it couldn't be tested. (Unlike Hooke's Law, which is readily tested, as much as we please.) But maybe I'm just showing my ignorance. I never had time to study the references that Benson suggested.

My general impression of the BLGB paper (for whatever it's worth), is that it shows that a collapse in the time frame observed was possible given the assumptions of the theory (many of which were reasonable; perhaps all were somewhat reasonable, though IIRC, it didn't take into account transport of elastic energy into the ground, nor any possible dampening effect of floors oscillating like membranes, nor plastic waves that exceeded the collapse speed* ).

I vaguely recall concluding that their model was probably very good for when the collapse really got going, something like halfway done. However, that's the part of a collapse where you really don't need explosives, even to make sure that there's no chance of toppling over.

Sorry, I don't remember more clearly. Again, I don't have the technical background to understand the later works, fully, anyway.


BTW, have you ever looked at the papers of Charles M. Beck (http://forums.randi.org/showthread.php?t=117311), posted at arxiv? They are way over my head. His analysis suggested CD:

We examine four WTC 7 descent curves, labeled "C," "E," "N," and "O," either anonymously published, or confidentially communicated to us. Descent curve describes apparent height of a collapsing building as a function of time. The set "C" suggests that there are three active phases of collapse. Phase I is a free fall for the first $H_1\simeq28$m or $T_1\simeq2.3$s, during which the acceleration $a$ is that of the gravity, $a=g=9.8$m/s$^2$. In Phase II, which continues until drop $H_2\simeq68$m, or $T_2\simeq3.8$s, the acceleration is $a\simeq5$m/s$^2$, while in Phase III which continues for the remaining of the data set, $a \simeq -1$m/s$^2$. We propose that the collapse of WTC 7 is initiated by a total and sudden annihilation of the base (section of the building from the ground level to $H_1$), which then allows the top section (building above $H_1$) to free fall during Phase I, and then collide with the ground in Phase II and III. The total duration of the collapse, assuming that Phase III continues to the end, is in the range $7.8-8.6$s. We derive a physical model for collision of the building with the ground, in which we correct the "crush-up" model of Ba\v{z}ant and Verdure, J. Engr. Mech. ASCE, {\bf 133} (2006) 308, and estimate the magnitude of the resistive force in the top section. We compare our findings to those of NIST investigators and find an agreement with respect to the distribution of damage in the primary zone. We conclude that the building was destroyed in a highly controlled fashion. (emphasis mine)

His paper on WTC 1/2 is here (http://arxiv.org/abs/physics/0609105).


* Even a plastic wave traveling at 1/10 of 5,000 m/s or so is much faster than the collapse

[pgimeno]

Subsequent papers looked more relevant to a real collapse. (Which is a good thing since, as noted, BZ is illogical, and can't prove anything about a real world collapse.)

Care to explain what makes it illogical? It proves that in the most favorable scenario for collapse arrest, the building could not arrest the collapse, thus proving it was unstoppable once started, which was the point and is perfectly logical, so I'd like to see an explanation on why you think otherwise.

[femr2]

it would be useful if the form of the force function was provided, such that the model results can be replicated and parameter sensitivity tested.
I have been informed that the form of the force function was provided. My bad.

[ozeco41]

Yes, this is an area where misunderstandings have been and have the risk to be common.


So far, so good. That's precisely why I use this sentence:






That's a valid point that I certainly admit to have kind of handwaved because of my lack of knowledge in the field. I have a strong feeling that some of the results will apply equally to both the real case and the model, but I can't tell you precisely which ones. That's not only my sensation, though. In another forum someone made a comment from one of my sentences:


(Emphasis in original).

Wish I could be any more precise. Sorry, I can't. I have ventured an assumption regarding e.g. this quote from [BV] (p.312):

Detailed finite element analysis simulating plasticity and break-up of all columns and beams, and the flight and collisions of broken pieces, would be extremely difficult, as well as unsuited for extracting the basic general trends. Thus it appears reasonable to make four simplifying hypotheses: [...]


I assume that he knows how the simplifications he makes affect the obtained results and that he knows that they won't have a very significant effect on the results he intends to obtain.

But then, I guess I would need to be an engineer to be able to actually make an evaluation about that.
Comments noted - we are in broad agreement.

As for "...I would need to be an engineer to be able..." my experience as both a practising engineer and (for much longer) a manager of practising engineers is that many engineers "lose the plot". Whether you call it the "technical context" or the "big picture" they can get too close to detail. Somewhat parallel to the old adage "when you are up to your arse in alligators it's easy to forget that the objective was to drain the swamp". The need is to ask "why are we here and why are we doing this?" Another sub-set of the problem is the tendency to rush into intense maths and calcs without first working out where you are going and what you are trying to clarify by the maths.

Take the question of "crush up" of the top block. It is clear that most of the "top block" mass of both towers fell inside the outer tube of the lower tower. It's not clear how because of the dust clouds.

However think about how this falling top block landed on the lower and get past the confused tangle of bent and broken bits so we are really in the "global collapse".

Ask this question "Where did the oputer tube columns of the top block fall?"

There are three possibilities - viz:
(1) inside the lower tower tube so, in effect the top block was wedged inside the lower tower outer tube and still more or less intact;
(2) The top block outer tube columns fell outside the lower tower - which means that those top block columns were sheared of in the first stage of the global collapse; OR
(3) Some inside and some outside.

For several reasons I discount (3) and prefer (1) out of the remaining two options.

But let's pursue both a little.

Think only of one wall for simplicity. If the top block outer tube fell outside the lower tower outer tube THEN the top of the lower block outer wall of columns would act as a "knife blade" and shear the top block floors off their outer columns as almost the first stage of global collapse.

Conversely if the top block outer tube fell inside the lower tower outer tube THEN the underside of the top block outer wall of columns would act as a "knife blade" and shear the floors of the lower tower off their outer columns, again as almost the first stage of global collapse.

Now whichever of these it was the first impact of the outer floor area and outer tube columns lands on a floor and has only the shear strength of the floor joist to column connections to overcome. AND the only significant load transferred to the columns is the force resulting from that shearing.

So much for any forces of column buckling magnitude whether "crush up" or "crush down".

The third option takes a bit more explaining but the engineers should see that it changes little.

So I am dubious of any "crush up" style explanation which relies on column buckling forces. Including some papers which IIRC claim there was not sufficient upwards force to buckle columns. So what? There was no need for such high magnitude forces when the only force required was to shear one floor at a time off the columns.

(And dealing with the core is nearly as straightforward but no need to complicate this post further)

Suffice that Bazant's model is limiting case valid for the global collapse of WTC1 and WTC2.

It does not address collapse initiation.

It is not valid in detail to explain the global collapse of the twin towers.

[ozeco41]

....This is a concern imo. ...a concern which I have shared for some years.
....The crush fronts are essentially the result of *pancaking*, with ROOSD being a more detailed description... ..agreed!!!
...Why do the outputs from the model involving axial column impacts match behaviour, velocity profile and global descent time of a completely different mechanism ?...the world of engineering has many examples of approximations giving correct answers for wrong reasons. :) :rolleyes:
...(Especially when it is clear that actual column destruction was significantly slower in propogation rate than ROOSD) ...presumably column "destruction" for the core columns --- the outer columns were simply peeled off.

[femr2]

...presumably column "destruction" for the core columns --- the outer columns were simply peeled off.

In general, yes.

[metamars]

Care to explain what makes it illogical? It proves that in the most favorable scenario for collapse arrest, the building could not arrest the collapse, thus proving it was unstoppable once started, which was the point and is perfectly logical, so I'd like to see an explanation on why you think otherwise.

Use the search function, please. Here, at physorg, and the911forum.

It can't be "the most favorable scenario for collapse arrest" if it incorporates assumptions that both favor collapse, and that favor survival....

[femr2]

It can't be "the most favorable scenario for collapse arrest" if it incorporates assumptions that both favor collapse, and that favor survival....

Must be worth noting that core column destruction did arrest for significant portions of the core of both WTC 1 & 2.

[Major_Tom]

Pgimeno, post #27: "Certainly, Bazant doesn't deal with collapse initiation, where there is certainly room for a deliberate action against the towers. However, the amount of demolition theory believers that sustain that point of view is so low that they can be readily dismissed. Thus Bazant's comment as quoted is accurate in its context (the clear intention of dismissing claims on the merit of floor-by-floor explosive demolition) even if not scalpel-accurate."

In a demolition masked as a natural collapse, collapse initiation and the events leading up to it may be the only factors that can diferentiate between CD and natural collapse.

Just about every researcher whose comments I have been studying for the last few years would agree.

How would any collapse progression features like fall time and destruction of concrete differ between the two cases? Listing natural collapse progression features to distinguish between CD and natural collapse cannot provide "proof" of no CD since we expect the same results in both cases.

One example is fall time.

One of the authors of BLGB, Frank Greening, has this to say about the WTC7 fall time (Notice how fast real demolitions are seen to collapse):

E. Yarimer at London University appears to be one of the few engineer/scientists who has studied real building demolitions by explosives. He has at least two papers on this subject, both written back in the 1990s, (and unfortunately hard to find on the web).

Here is a quote from the first (1994) paper:

“The current practice in controlled demolition (CD) by explosives is to pre-weaken the building on most floors, and to blast only a portion of the floors, for example one floor in two, or one floor in three. Even so, the number of charges to be placed in individual boreholes can be large: up to 6000 charges have been used depending on the size of the job. The blast floors will readily disintegrate, but the non-blast floors need the force of the impact in order to break-up. Even on the blast floors, the perimeter walls above the ground floor are usually not charged for safety reasons, and they are expected to break up by impact. The entire process is driven by gravity but the downward velocities are attenuated by the energy absorption at the point of impact, and the motion will accelerate less than a case of free fall; it may even decelerate. A spectacular case of decelerating motion was that of Northaird Point in London in 1985, which came to rest with 10 floors still intact.”

In his second, (1996) paper, Yarimer used electronic and photographic timing devices to study a number of real CDs. One of great interest to the present discussion was the 1995 demolition of a 20-story high-rise known as Sandwell East Tower. This demolition showed - as was observed for some other CDs studied by Yarimer - a latency period of ~ 1.5 seconds before significant bulk motions were detected.

I have taken Yarimer’s data to look at the accelerations for the Sandwell East Tower CD. Some time-drop data for the first 5 seconds are: 0 s, 0 m; 1 s, 0 m; 2 s, 1.8 m; 3.0 s, 10 m; 4.0 s, 22.3 m; 5.0 s, 35.9 m. These data show the collapse was well below free fall. Indeed, Yarimer states in his discussion of this data: “Near time t = 0, the calculated accelerations are influenced by the observed latency, thus lifting the estimate of the upwards reaction force.” It appears that even Yarimer had t(0) problems!

Nevertheless, I have analysed Yarimer’s data (with allowance for the t(0) problem) using the same approach many of us have applied to WTC 7 collapse data. What is most significant is that, even with a time shift of ~ 1.5 seconds, the Sandwell East building fell only about 40 meters in the first 4 seconds of bulk motion with an acceleration of no more than 5 m/s^2. And let’s remember that this was observed for a real-world CD on a 20-story building. Scaling this result to a 47-story, (WTC-7-sized building), I would predict a 50 % collapse to take at least 6 seconds and allowing for a latency period of about 1.5 seconds, a full collapse to take ~ 10 seconds or more.

D. Isobe et al. have carried out finite element calculations on a 20-story steel framed building subjected to a Kobe-wave type of seismic collapse. Isobe found that incremental collapse begins
after an initial 26-second period of vibration during which time plastic hinges are formed and column fractures occur near the ground level of the building. The modelled structure was 50 % collapsed about 10 seconds after the first bulk downward motion, and still only about 35 % collapsed after 14 seconds!

Thus we see experimental and theoretical confirmation that the global collapse of a 20-story building would take at least 10 seconds to partially collapse from deliberate man-made explosive or natural seismic trauma to lower portions of its structure.

One can only wonder what mysterious combination of forces brought down a 47 story building in less than 8 seconds....."

(Source: The 9/11 Forum)


Notice that even real demolitions are not measured to fall at freefall or anywhere close.

(Also note that Greening has serious questions about WTC7).

We see numbers like 0.6g average accelerations for known demos.

So how can anyone distinguish between CD and natural collapse for WTC1 by citing average acceleration and fall times? They can't.

[AZCat]

Must be worth noting that core column destruction did arrest for significant portions of the core of both WTC 1 & 2.
Has anyone ever estimated the height of the remaining section of the core?

[AZCat]

Notice that even real demotions are not measured to fall at freefall or anywhere close.

(Also note that Greening has serious questions about WTC7).

We see numbers like 0.6g average accelerations for known demos.

So how can anyone distinguish between CD and natural collapse for WTC1 by citing average acceleration and fall times? They can't.
Of course. You still have to account for momentum transfer, which makes up the bulk of the "slow down".

[femr2]

Has anyone ever estimated the height of the remaining section of the core?

As the remnants are not *level* there's quite a difference between the highest elevation, and lowest, but it's fairly clear that core destruction began to arrest around the upper mechanical floor region (WTC1). WTC 2 is similar, but slightly more even. Full width of WTC1 core survived lower down. Will grab some metrics later. Will have to wade through...
wtc-1-core-remnant-motion (http://the911forum.freeforums.org/wtc-1-core-remnant-motion-t185-15.html)
and
wtc-2-core-remnant-motion (http://the911forum.freeforums.org/wtc-2-core-remnant-motion-t191.html)

[AZCat]

As the remnants are not *level* there's quite a difference between the highest elevation, and lowest, but it's fairly clear that core destruction began to arrest around the upper mechanical floor region (WTC1). WTC 2 is similar, but slightly more even. Full width of WTC1 core survived lower down. Will grab some metrics later. Will have to wade through...
wtc-1-core-remnant-motion (http://the911forum.freeforums.org/wtc-1-core-remnant-motion-t185-15.html)
and
wtc-2-core-remnant-motion (http://the911forum.freeforums.org/wtc-2-core-remnant-motion-t191.html)

Cool - I'll read this later. Thanks for answering.

[pgimeno]

Pgimeno, post #27: "Certainly, Bazant doesn't deal with collapse initiation, where there is certainly room for a deliberate action against the towers. However, the amount of demolition theory believers that sustain that point of view is so low that they can be readily dismissed. Thus Bazant's comment as quoted is accurate in its context (the clear intention of dismissing claims on the merit of floor-by-floor explosive demolition) even if not scalpel-accurate."

In a demolition masked as a natural collapse, collapse initiation and the events leading up to it may be the only factors that can diferentiate between CD and natural collapse.

Just about every researcher whose comments I have been studying for the last few years would agree.

I don't know what people will you refer to when you say researcher. Eric Hufschmid calls himself a researcher and says that the towers fell in about 8-10 seconds and that that is proof of CD.

But you're making a strawman of my argument, by focusing on "the last few years" and a handful of people. The mainstream truther world and their theories is what Bazant is addressing. What am I talking about?


Typical truther claim 1: The towers fell at free fall or near free fall and that proves it was a CD.

Example 1: www.journalof911studies.com/volume/200703/Sudden_collapse_initiation_impossible.pdf
Excerpt:It appears therefore that the official concept of a free fall collapse of the upper portion through the initiation storey, due to heat effects from fire, is a fantasy. If the temperature did become high enough for collapse to occur it could not have happened in the observed manner. 9 In particular it could not have been sudden and thus could not have produced the velocity, and hence the momentum and kinetic energy, upon which the official story depends for the second stage of collapse. In contrast, all observations are in accord with the use of explosives in a timed sequence.

Example 2: www.911truth.org/article.php?story=20050927220055973
Excerpt:The Commission also did not mention that the collapse of each tower had at least 10 features characteristic of controlled demolitions. For example, each collapse (1) began suddenly, (2) came straight down, (3) occurred at virtually free-fall speed, and (4) produced an enormous amount of dust, which happens when explosives pulverize concrete into tiny particles.

Example 3: www.serendipity.li/wtc5.htm
Excerpt:Thus the speed of the collapse (not much more than the time of free fall) is conclusive evidence that the Twin Towers were brought down in a controlled demolition involving the use of explosives (or some other destructive technology) at all levels.

Example 4: www.erichufschmid.net/pdf/Painful_Questions_chapter_7.pdf
Excerpt:The video shows that the collapse occurred at the same rate as if somebody had dropped the steel beams in air from the top of the building. It aint possible for steel beams to bust through all of those floors without slowing down!

Example 5: www.physics911.net/thermite
Excerpt:The observed near free-fall times of the WTC towers (and WTC7) were a dramatic signature of a controlled demolition.


Typical truther claim 2: The seismic records are proof of CD.

Example 1: www.erichufschmid.net/pdf/Painful_Questions_chapter_7.pdf
Excerpt:According to the Columbia University Seismology Group, the North Tower created a shock of magnitude 2.3 (Figure 7-1), while the South Tower created a shock of 2.1. Their report also shows that the South Tower collapsed in 10 seconds and the North Tower collapsed in 8 seconds.

Example 2: www.serendipity.li/wot/bollyn2.htm
Excerpt:The Palisades seismic record shows that — as the collapses began — a huge seismic "spike" marked the moment the greatest energy went into the ground. The strongest jolts were all registered at the beginning of the collapses, well before the falling debris struck the earth. These unexplained "spikes" in the seismic data lend credence to the theory that massive explosions at the base of the towers caused the collapses.

Example 3: drjudywood.com/articles/BBE/Shake.html
Excerpt: So, if it takes at least 9.22 seconds for the roof to hit the ground, how could the ground quit rumbling after 8 seconds?


Typical truther claim 3: pulverization of concrete is indicative of CD.

Example 1: See the second excerpt in Truther Claim 1, relevant part of the excerpt: "produced an enormous amount of dust, which happens when explosives pulverize concrete into tiny particles".

Example 2: www.physics911.net/thermite
Excerpt:Consider also that apologists for the official conspiracy theory propose that 30% of the gravitational collapse energy was necessary to create the pyroclastic cloud of debris: that is, in their own analysis, this energy came out of the gravitational energy. [...]

The implication from the above is that there were major energy sources other than gravitational involved in the WTC towers collapses.

Example 3: www.plaguepuppy.net/public_html/physics/
Excerpt:In trying to understand what actually happened during the collapse of the World Trade Towers, perhaps the most glaring problem with the "official" models is their inability to explain the enormous dust clouds generated by the collapses.

I have found many, many more, but it's a tough work to go through sites, select quotes and format them here. And you surely already knew, but I'm not writing only for you.

These are typical claims that Bazant addressed. He no doubt contributed in changing the mind of some truthers, who are now attacking him... for addressing them.

Some of these claims may be getting a bit weary now and getting out of fashion, but they were quite alive by the time [BLGB] was published and are still alive in many places as our recurring truthie visitors prove. Even Szamboti is cited to have freely fallen for that, in the first quote.

[cmcaulif]

Considering that Bazant Zhou postulates an axial impact - in their theory, not in the real world collapse - you'd think that they would have referred to the literature on axial impacts which existed well before their paper was written. I'm referring to a body of technical literature, some (probably most) of which has been experimentally tested.

I still don't know if using a more realistic, purely elastic theory, for an idealized, axial impact would result in the elastic limit being exceeded, or not. I tend to think so, based on calculations I've done, but I'm still not sure, since the situations weren't good enough matches to the BZ scenario. (As for absurdities of the BZ model which predispose it towards collapse, you can search my other writings on the subject. They mixed assumptions which both favored collapse, as well as favored survival, and made no attempt to quantify the relative implications of each. Thus, their paper is illogical! It proves nothing even remotely related to a real world collapse, because it can prove nothing. Kind of interesting that self-styled debunkers would fail to notice this, huh?)

However, an axial impact on a steel rod which exceeds the elastic limit doesn't automatically result in failure. Depending on the details of the problem, you could arrest the striking weight's motion, with energy being dissipated in plastic deformation. (This is what Gordon Ross attempted to calculate, though without benefit of the knowledge of the literature which already existed. Gordon was quite open to knowledgeable input and criticism, contrary to what some of the people who have smeared him have implied. I know this from personal communication. Unfortunately, I hadn't yet run across the body of knowledge about elastic/plastic deformations which follow axial impact, when we had these communications.) The plastic deformation wave travels at about 1/10th the speed of an elastic wave, in steel.

Ari-Gur, to name one researcher in elastic/plastic collision theory, has a relatively simple theory for this, which he has tested, and got fairly good experimental confirmation of his theory.


In the closure to Gourley's comments by Bazant and Le, they give the equations of motion for a two way crush, which includes variable crushing resistance rather than the constant energetically equivalent resisting force used in the papers.

Why not use these equations of motion, but substitute the curve F(u) that bazant used with a curve developed from pulse buckling theory?

Another approach, since the EoM is going to solved numerically (incrementally), you could calculate F at each time step using a stress update based on a rate dependent plasticity theory. This would probably make the model more general.

[pgimeno]

Care to explain what makes it illogical?
Use the search function, please. Here, at physorg, and the911forum.

It can't be "the most favorable scenario for collapse arrest" if it incorporates assumptions that both favor collapse, and that favor survival....
A simple "no" would have sufficed.

[Major_Tom]

Pgimeno, then perhaps the researchers I pay most attention to are not "typical truthers" because none of them advocate any of the arguments you have posted.

You are posting arguments by what I have called the "Tweedle-dee" side of the argument.

Tweedle-dee is not hard to debunk. But Tweedle-dee does not represent me or any of the researchers I frequently read in any way.

The most interesting arguments have been basically ignored while Tweedle-dee "debated' Tweedle-dum.

Bazant proves Tweedle-dee is wrong. I could do that too.

[pgimeno]

Pgimeno, then perhaps the researchers I pay most attention to are not "typical truthers" because none of them advocate any of the arguments you have posted.

Maybe, or maybe not. There are about as many conspiracy theories as truthers. There's a million versions to pick from. They may have chosen to distance from these nonsensical claims just because they exceed their rationality threshold, but be adhering to other nonsensical claims, like the demolition one, because it somehow fits within that threshold, yet it still being, just like the ones I posted, merely a faith-based idea with an absolute lack of evidence.

Bazant proves Tweedle-dee is wrong. I could do that too.
In an engineering journal with engineering arguments? Let me express my reserves.

[Major_Tom]

About 2 years ago I wrote: "Note: We must always view the problems of collapse progression and collapse initiation as 2 entirely different physics problems.

Coming up with a useful basic model of unassisted collapse progression once the building starts to move downward says nothing about the physics problem of collapse initiation."

Frank Greening, one of the authors of BLGB, replied: "Major Tom: I agree!

In fact, after an upper block has dropped a few floors, a "natural" collapse is essentially indistinguishable from a controlled demolition.

So yes, it is all about collapse initiation.....".
(Source: The 9/11 Forum)

That was in 2008. Basically every decent researcher I have encountered seems to agree on that point.


Dave Rogers also recognized this and states it eloquently here:

I've had a quick look through the paper, and I don't see anything particularly contentious about the hypothesis that the collapse progressed, broadly speaking, in the way you describe. I don't see anything contentious, either, about the statement that this mechanism does not prove that the collapse was unassisted by demolition devices; indeed, I suspect that no feature of collapse propagation could conceivably prove any such thing, because even a controlled demolition using explosives exhibits a natural collapse progression. It's collapse initiation that's the key differentiator in this instance.

Looking at collapse initiation and the events leading up to it is not my idea alone, and it shouldn't be confused with claims of no planes and space beams.

It shouldn't be confused with my person at all. It is not my idea.

Every decent 9/11 researcher from both sides of the fence can agree that the original initiation of each collapse and the events leading to it are perhaps the only time period in which an intentional demolition and a natural collapse are distinguishable.


It is foolish to miss this point and associate a careful study of the collapse initiation sequences of each building with claims of space beams, freefall for all 3 towers and no planes.

[DGM]

Looking at collapse initiation and the events leading up to it is not my idea alone, and it shouldn't be confused with claims of no planes and space beams.

It shouldn't be confused with my person at all. It is not my idea.

Every decent 9/11 researcher from both sides of the fence can agree that the original initiation of each collapse and the events leading to it are perhaps the only time period in which an intentional demolition and a natural collapse are distinguishable.


It is foolish to miss this point and associate a careful study of the collapse initiation sequences of each building with claims of space beams, freefall for all 3 towers and no planes.
Look as much as you want, who's stopping you? In fact I personally give you my blessing (for all it's worth).

The only thing I ask is you don't draw conclusions based on speculation.

Have at it.


:)

[pgimeno]

Looking at collapse initiation and the events leading up to it is not my idea alone, and it shouldn't be confused with claims of no planes and space beams.

Looking for traces of CD in the collapse initiation, on the other hand, is easy to be confused with such claims, as they are all crazy ideas which don't count with a shred of evidence.

[ozeco41]

About 2 years ago I wrote: "Note: We must always view the problems of collapse progression and collapse initiation as 2 entirely different physics problems.

Coming up with a useful basic model of unassisted collapse progression once the building starts to move downward says nothing about the physics problem of collapse initiation."...
Yes!! And do I need to add "of course"?
The two phases of:
(1) "initial collapse" - which was when the top block started to drop; AND
(2) "global collapse" - which is what followed as the top bit smashed its way down destroying the lower tower;
..are distinctly separate and separable phases.
The global collapse can be explained relatively easily. It was truly inevitable as NIST concluded and stopped investigating at that point. Similarly Bazant and some others showed that the global energy available was sufficient to maintain that progressing global collapse - despite making some very conservative assumptions. Then, within the energy envelope of Bazant et al it is fairly straightforward the look at the details of how the collapse progressed. Then, because the real mechanism was far less energy absorbing than the Bazant approximation, consideration of the details also "Proves" that collapse was inevitable.

So much for the later, global collapse, stage.

The earlier stage of the lead-up to the initial collapse is harder to "prove" given that the mechanisms of this stage are mostly hidden. It is relatively straightforward to envisage how sagging floor joists could pull outer columns inwards; also how heating of the lower chord members of the floor joists could cause sagging and pull-in on the columns. From there how a "cascade" failure could develop. There is at least one clear picture of the two components and another showing many columns pulled inwards. The difficulty for "proof" is that there is no way to show that sufficient columns were affected by this mechanism OR to identify other mechanisms involved in the overall build up of the cascade failure.

Sure it is easy to rebut the usual "truther" bits of claims and the lack of any pro-truther coherent overall explanation of the initial collapse mechanism. But to the outsider "proof" of the sufficiency of the collapse mechanisms without demolition still depends on the logistic impossibility of the use of demolition in the impact zone only and without discovery before during or after the event.

But, on your original point, the two stages of what I term "initial collapse" ands "global collapse" are separate AND proof or disproof of demolition depends solely on the "initial collapse" phase. Reasons why the "truther" side may choose to confuse the two are obvious. It is not clear what benefit, if any, accrues to the debunker side by allowing or creating confusion of the two stages.

[ozeco41]

Looking for traces of CD in the collapse initiation, on the other hand, is easy to be confused with such claims, as they are all crazy ideas which don't count with a shred of evidence.
From my perspective the problem is one of discussion process.
Two or three years back it was possible to hold a reasoned discussion of specific issues and with parties from the opposing extremes.

Since all the legit topics have essentially been dealt with many times today's "discussions" tend to be polarised in to two extreme camps with personal denigration taking priority over discussion of the topic. For example my immediately preceding post and Major_Tom's point that the two phases of collapse are separate.

Without doubt a valid point. However the relevance to this thread being that the initial collapse is outside the scope of Bazant's model. So, beyond identifying that it is "out of the ball park", discussion of the initial collapse belongs in another thread. Mea culpa on that point to the extent that my previous post summarises the comparative ease/difficulty of proof for the two stages.

[leftysergeant]

We should be talking about how those 85% apparently simultaneously ceased to exist as columns.

Only an utter idiot thinks that they would have to simultaneously fail to initiate collapse. They progressively failed, if in a short span of time. You still have thousands of tons of steel, including a nasty great steel girder umbrela at the top, being borne sort of catawampus as the fires start. At this point, some of the burden of holding up the umbrella has been shifted to two or three columns, subjecting theem to new lateral stresses in addition to the axial stress they were supposed to bear until eternity or rust made them stop supporting it. Then you have the fires heating the steel and causing it to expand unevenly, putting more strain on the columns in several different directions. Sooner or later, this causes a joint to break, then another, then another and all of a sudden they are failing in files.

Snap and THUD! Look out below.

[bill smith]

Only an utter idiot thinks that they would have to simultaneously fail to initiate collapse. They progressively failed, if in a short span of time. You still have thousands of tons of steel, including a nasty great steel girder umbrela at the top, being borne sort of catawampus as the fires start. At this point, some of the burden of holding up the umbrella has been shifted to two or three columns, subjecting theem to new lateral stresses in addition to the axial stress they were supposed to bear until eternity or rust made them stop supporting it. Then you have the fires heating the steel and causing it to expand unevenly, putting more strain on the columns in several different directions. Sooner or later, this causes a joint to break, then another, then another and all of a sudden they are failing in files.

Snap and THUD! Look out below.

When only 15% or less of the columns near the top of a tall building are gone or damaged you do not talk about a 'top block' and a 'bottom block'....you talk about a hole in the building.

But if some kind pf magic eliminates the remaing 85% of the columns in the area of the hole THEN you can talk about a 'top block' and a 'bottom block'.

But first you must talk about where the 250 or so massive columns disappeared to and how they all disappeared at the same time.

You see there is no way that they could all have given way simultaneously. Even a progressive collapse like you postulate would see the building visibly distort and lean prior to collapse.

It's such a relief to throw Bazant out the window..

[Major_Tom]

Pgimeno and others,

On the question of applicability, we need to honestly recognize examples of people clearly crossing the line by applying the results of the Bazant 1-D stick model to real 3-D buildings.

True or false? In the following quote R Mackey clearly crosses the line, ascribing attributes of the Bazant 1-D stick model to a 3-D description:



Think of it in terms of impulse -- the total change of momentum at a particular impact. Impulse is equal and opposite, by conservation of momentum. Impulse is equal to F delta-T (force times the time over which the force is applied), or M delta-V (the raw change of momentum in its familiar definition P = m V).

When we look at the "upper block," it's delta-V is smaller than the delta-V experienced by the newly broken part of the lower block. As you say, the upper block decelerates by an average 1/3 g, while the lower block accelerates by an average 2/3 g. This is because the participating part of the lower block masses less than the participating part of the upper block -- it really is the compacted mass and upper block versus a small number of floors at a time, not the entire lower block.

The reason only part of the lower block participates at any given time is because the lower block is still a mostly intact sparse structure of braced columns. When it's hit, the columns lose bracing, get loaded eccentrically, shear their welds and bolts, and in some cases are totally overwhelmed and fracture entirely. These pieces break at a stress much too low to actually support the descending mass. This also has nothing to do with the strength of the perfectly intact building -- the descending rubble heap isn't contacting the lower structure at its strongest points, and it's introducing brand new failure modes, so the effective opposing strength of the lower structure is far lower than its ideal carrying capacity. Furthermore, where the lower structure does resist at or near its ideal strength, it can only do so for a very brief delta-T -- until reaching its failure strain, which takes only about ten milliseconds at the speeds of collapse -- and this is not enough to amount to all that much total impulse.

The upper chunk, in contrast, is cushioned by a thick layer of rubble. This is compacted about as far as it can, thus it doesn't have those complex failure modes and it doesn't suffer much more "damage" even at much higher stresses. So the rubble pile remains, and the lower structure gives way. This is for the same reason you don't sink into the ground, even though you can push your finger easily through a cupful of soil.

The "upper block," what remains of it, rides on top of this cushion of debris. It is supported pretty well. It also only decelerates at that lower rate, thanks to the much greater inertia of the upper block + debris. So the only real force it suffers is the inertial force, i.e. its own self-weight times its deceleration, again about 1/3 g. It can be expected to survive this deceleration. It's only when the rubble pile has nowhere else to go and the upper block has to suddenly stop, dissipating all of its momentum in mere milliseconds, that it totally fails.

Again, this is slightly idealized, but you get the point. Unless you're a Truther.

I think this is a good example of how not to apply the crush down, then crush up attributes of the 1-D stick model to 3-D cases. Do others agree?

[bill smith]

Absolutely. It's a pleasure to see the Bazant distraction being frogmarched out of the real-world event.

[beachnut]

Pgimeno and others,

On the question of applicability, we need to honestly recognize examples of people clearly crossing the line by applying the results of the Bazant 1-D stick model to real 3-D buildings.

True or false? In the following quote R Mackey clearly crosses the line, ascribing attributes of the Bazant 1-D stick model to a 3-D description:



I think this is a good example of how not to apply the crush down, then crush up attributes of the 1-D stick model to 3-D cases. Do others agree?
You continue to produce nothing but talk and attack a model you can't refute, or match because you have no knowledge or skills to do engineering work. Publish your tripe and see what other engineers think of your failed attempts to back in CD while being obsessed with NIST and Bazant. You are paralyzed to do anything because of your biased CD delusion and lack of knowledge in engineering, math, and physics.

You are acting like Balsamo with your 1-D rant and exposing your lack of engineering skills by showing you don't understand models. Wow, you found the quote function! Progress. Prove your claims, stop exposing your lack of knowledge attacking NIST and Bazant; this is good advice, you can't prove your points attacking NIST and Bazant. But you can't help it.

Publish your work. At least bill smith support you with all her engineer skills and idiotic 911 delusions.

[leftysergeant]

Bazant's work is valid as far as it concerns calculating the amount of energy avaialble to the work of crushing the towers. In thereal world, such progressinve collapses would almost invariably procede as Bazant described.

NwFHEoiUZ7o


Where it all falls apart, regarding the towers is in the fact that, unlike most buildings, the centers of the towers offered the greatest resistance and thus started crushing up almost at once. This destroyed any structural integrity the top portion would have had, causing it to discombobulate almost at once so that you have rubble rather than a solid block of building.

But the mass does not go away. It stayed there inside the perimeter columns until it shoved the perimeter columns out of the way.

At any rate, idiot boy Gage's work depends on Bazant's model being wrong in every case, which is the point of little Dickie's cardboard box drop. But verinage is a direct application of the principles that Bazant applies.

[leftysergeant]

Absolutely. It's a pleasure to see the Bazant distraction being frogmarched out of the real-world event.Nothing of the sort. Bazant's values were right. Twoofers, especially Gage, are wrong. The energy is there and is transferred at the rate at which Bazant supposes. Just that nasty center structure reducing the top to a mass of rubble (which is still substantial, ) rather than a (far less dense) empty block.

The upper columns, being more badly distorted, separated easily on contact with the lower columns, thus robbing the whole upper bl;ock of its rigidity.

[ozeco41]

Bazant's work is valid as far as it concerns calculating the amount of energy avaialble to the work of crushing the towers. In thereal world, such progressinve collapses would almost invariably procede as Bazant described....
I agree broadly with this.
1) There is no doubt as to "...amount of energy available to the work of crushing the towers..."
2) IMO the main reason most real world progressive collapses would probably progress as per Bazant is that most real world towers are not tube in tube design. Two aspects of collapse follow from the difference.
(a) "normal" buildings with columns and beams in a grid arrangement would act closer to homogeneous than the tube-in-tube of WTC1 & 2 and Bazants base assumption of axial loading of columns would be most likely valid or very close approximation; CONTRAST
(b) WTC 1 & 2 where the vulnerability to collapse was implicit in the tube-in-tube design and there was no axial loading of outer tube columns and (by reasoning) few if any core columns. (The former by observation of evidence - the latter by reasoning.)
Whilst my explantion would be somewhat different to this:....Where it all falls apart, regarding the towers is in the fact that, unlike most buildings, the centers of the towers offered the greatest resistance and thus started crushing up almost at once. This destroyed any structural integrity the top portion would have had, causing it to discombobulate almost at once so that you have rubble rather than a solid block of building.......I fully support the conclusion you reach: ...But the mass does not go away. It stayed there inside the perimeter columns until it shoved the perimeter columns out of the way.... or they simply fell over once the bracing from the floors was lost.
...At any rate, idiot boy Gage's work depends on Bazant's model being wrong in every case, which is the point of little Dickie's cardboard box drop. But verinage is a direct application of the principles that Bazant applies.Yes, yes and yes.

[ozeco41]

Pgimeno and others,

On the question of applicability, we need to honestly recognize examples of people clearly crossing the line by applying the results of the Bazant 1-D stick model to real 3-D buildings... Since I joined the public on internet debate of WTC and 9/11 my primary objectives have been (1) to answer the question "Demolition or Not?" THEN (2) Since there was no demolition, to understand and explain to myself and others why and how the Twin Towers fell.

I therefore approach the problem of (2) from the evidence as to what actually happened to WTC1 and WTC2 and I form conclusions as to the mechanisms involved. It is of interest to look at the analyses of other persons - independent of which "side" of the debate they occupy.

My approach therefore is to use theory if it is needed to support analysis of the actual events at WTC on 9/11. That is 180% opposite course to those who formulate theoretical solutions and try to fit them to the real events. And the distinction is not trivial.

To me the Bazant model has severe limitations in explaining the detail of how WTC1 and 2 fell. However the alternate approach by finite elements would be inordinately complex and would rely on so many assumptions about structural components which could not be observed as to make the exercise futile even if it was possible.

The broad parameters of the actual collapses are available in video evidence. Key among those bits of evidence is the fact that the bulk of descending mass passed down inside the outer tube. Allowing for the fact that the descent was probably mostly core on core and floor on floor it is readily argued that the floor on floor impact struck the lower floors seriatem one at a time. 10 or 20 floors hitting one floor dynamically does not need masses of calculations to prove "overwhelming load". Careful thinking about what happens to the core on core bits AND allowing for possibly some core to floor overlaps and a ball park explanation emerges. Key point being that the assumptions to support such ball parking are not any worse than the assumptions needed for Bazant modelling or finite element if anyone seriously considered it.

So, bottom line for me is that Bazant is of little value. He "proves" sufficient global energy to sustain collapse and that is all that is useful as secondary support to me as I seek to explain WTC Towers collapse. And my interest is explaining those collapses without demolition as a factor.

I have no interest in supporting Bazant any further. I am mildly frustrated by the number of threads which claim explicitly that they are supporting Bazant as a generic model but then go nice and ambiguous about what the assumptions of the model are and whether or not those assumptions limit the application of Bazant to WTC.

So I apply this form of test where people are arguing Bazant vis-a-vis WTC Twin Towers:
"Is the objective to defend Bazant or is it answer questions about WTC collapses?"

First 'Principle of War' (British and Aussie version) Selection and Maintenance of the Aim. The US version says the same thing in one word 'Objective'.

My objective is "Explain WTC Demolition or not?" - side line discussions about Bazant don't help. And I don't think Bazant's model fits WTC1 & 2 in any way which is of much help to me. And I tend to ignore attempts to apply Bazant in detail to WTC events.

So Mr Mackey's use of Bazant is his choice. He and I agree on the global outcome "no demolition". Nothing Mr Mackey posts weakens my position on no demolition. But nor does his use of Bazant modelling or Bazantphile concepts such as "crush up/crush down" change any of my understandings of what actually happened.
So:...True or false? In the following quote R Mackey clearly crosses the line, ascribing attributes of the Bazant 1-D stick model to a 3-D description:.....I skip over the Bazant stuff. And:...I think this is a good example of how not to apply the crush down, then crush up attributes of the 1-D stick model to 3-D cases. Do others agree?...personally I regard the whole "crush up/crush down" concept as commonly used in explanation to be as useless as the faeces of a male bovine. And on my favourite forums I could have used the blunt Aussie version of that word.

[Major_Tom]

Ozeco, as for the actual collapse propagation of the towers, have you read the OOS collapse propagation study in the OP of the "OOS collapse propagation model" thread?

If not, I think you will appreciate it in that it is the best overall descriptive collapse propagation model which matches all observables available.

Through the model you will see that I have no problem with runaway destruction of the towers. Neither do any of the researchers with whom I work and share information, many of whom at "truthers".

Many of us allow for runaway propagation to earth through the open office space (OOS) areas between the perimeter and the core all the way to earth.

Check it out in that I think you will like it.

Leftysergeant is describing much the same thing as the OOS model.

[beachnut]

Ozeco, as for the actual collapse propagation of the towers, have you read the OOS collapse propagation study in the OP of the "OOS collapse propagation model" thread?

If not, I think you will appreciate it in that it is the best overall descriptive collapse propagation model which matches all observables available.

Through the model you will see that I have no problem with runaway destruction of the towers. Neither do any of the researchers with whom I work and share information, many of whom at "truthers".

Many of us allow for runaway propagation to earth through the open office space (OOS) areas between the perimeter and the core all the way to earth.

Check it out in that I think you will like it.

Leftysergeant is describing much the same thing as the OOS model.
Got any evidence for your CD delusion yet? You waste time on Bazant when you should be critiquing your own failed conclusions.

[ozeco41]

Ozeco, as for the actual collapse propagation of the towers, have you read the OOS collapse propagation study in the OP of the "OOS collapse propagation model" thread?

If not, I think you will appreciate it in that it is the best overall descriptive collapse propagation model which matches all observables available....
I have read it. The part in the OP is brief and goes further into "what happened to the core" detail than I have considered necessary. I have also read the subsequent posts which expand on your explanation. It is however consistent with my explanations first published on the now defunct Richard Dawkins Net forum. I rewrote my explanation for essentially the same forum audience when many members of RDNet moved to "ratskep". The rewrite is here: http://www.rationalskepticism.org/conspiracy-theories/the-obligatory-9-11-thread-t515-680.html#p135852 As you will see my version is a reasoned analysis which does not resort to mathematics - consistent with my overall philosophy of "get the reasoning right before engaging maths" I wouldn't trust myself with maths these days on something as complex as WTC collapse - even if I made massive simplifying assumptions al la Bazant. Through the model you will see that I have no problem with runaway destruction of the towers. Neither do any of the researchers with whom I work and share information, many of whom at "truthers"... ...we used to maintain a clear distinction between genuine sceptics who doubted the "no demolition" case and "truthers" or "CTs". So there were three camps back in 2007 when I first became involved in 9/11 discussions. (Probably four because many "CTs" pretended to be sceptics :D ) The distinction seems to have been lost over recent times - you are classified either as "debunker" or "truther" and often it seems that those with any doubt about the debunker gurus etc are classed as truthers.
Check it out in that I think you will like it....it is in same ball park as mine. My reasoning in the single post is lengthier than your OP standing alone. I have only skim read the extra explanation in later posts - methinks here is not the place for a critique. :D
Leftysergeant is describing much the same thing as the OOS model....sure looks like it to me.

[bill smith]

Nothing of the sort. Bazant's values were right. Twoofers, especially Gage, are wrong. The energy is there and is transferred at the rate at which Bazant supposes. Just that nasty center structure reducing the top to a mass of rubble (which is still substantial, ) rather than a (far less dense) empty block.

The upper columns, being more badly distorted, separated easily on contact with the lower columns, thus robbing the whole upper bl;ock of its rigidity.

Doesn't Bazant's theory depend on a 'rigid upper block' ?

[ozeco41]

Doesn't Bazant's theory depend on a 'rigid upper block' ?"Rigid" is not the right word. "Integral" would be more appropriate. He takes as starting point that the 'upper block' was still structurally intact - ie not broken into component parts. He draws conclusions as to when it would break into component parts. BUT he accepts that interactions would be a mix of contacts involving elastic and plastic deformations. So "rigid" is not the word for a mix of elastic and plastic effects.

[Myriad]

Doesn't Bazant's theory depend on a 'rigid upper block' ?


Well, yeah. Bazant's best-case scenario for collapse arrest depends on the upper block remaining intact, so that all the impacts can be column-on-column and as much energy as possible can be absorbed in 3-hinge buckling of all the columns.

If the upper block falls apart, so does the best-case scenario -- making collapse arrest even less of a possibility.

Oops.

Respectfully,
Myriad

[bill smith]

"Rigid" is not the right word. "Integral" would be more appropriate. He takes as starting point that the 'upper block' was still structurally intact - ie not broken into component parts. He draws conclusions as to when it would break into component parts. BUT he accepts that interactions would be a mix of contacts involving elastic and plastic deformations. So "rigid" is not the word for a mix of elastic and plastic effects.

I'm sure that you will accept that a mixture of elastic and inelastic parts is basically only as strong as the elastic parts. (Chains and weakest links and so on)

So if 'Bazants's 'rigid' is only as strong as that I can see what you mean about 'rigid' not meaning 'rigid'. at all.

Are there any other words that are seriously misapplied by Bazant ?

[carlitos]

...we used to maintain a clear distinction between genuine sceptics who doubted the "no demolition" case and "truthers" or "CTs". So there were three camps back in 2007 when I first became involved in 9/11 discussions. (Probably four because many "CTs" pretended to be sceptics :D ) The distinction seems to have been lost over recent times - you are classified either as "debunker" or "truther" and often it seems that those with any doubt about the debunker gurus etc are classed as truthers.
I'm not sure how to take this aspect of Major Tom's theory. Maybe he has no claim at all, but he doesn't seem to rule out "a demolition team."

If unassisted ROOSD is possible, is this proof that the collapses were natural?

Not at all. It means that in the WTC1, 2 design a runaway destruction potential has always existed in the OOS spaces completely surrounding the cores which a demolition team can exploit by setting up sufficient initial conditions higher in the towers.

[bill smith]

Well, yeah. Bazant's best-case scenario for collapse arrest depends on the upper block remaining intact, so that all the impacts can be column-on-column and as much energy as possible can be absorbed in 3-hinge buckling of all the columns.

If the upper block falls apart, so does the best-case scenario -- making collapse arrest even less of a possibility.

Oops.

Respectfully,
Myriad

Isn't it amazing how easily the Bazant distraction gets overlaid onto the real event Myriad.

Why are we not talking about the hole in the building and where the 250 massive steel columns disappeared to- and all simultaneously at that.

That's the real mystery.

[Major_Tom]

Ozeco post 67: "As you will see my version is a reasoned analysis which does not resort to mathematics - consistent with my overall philosophy of "get the reasoning right before engaging maths".

I totally agree. An accurate description of the mass flow and the actions of perimeter, core in as much visual detail as possible.

THEN, when you feel you have something, you express it in mathematical form. I agree.

ROOSD has some very interesting mathematical properties. Excellent budding research by femr who has extracted the observed propagation front down the WTC1 SW corner over a good 40 floors. Bazant never had access to propagation data like this.

A basic mathematical model has been attempted on the data by OneWhiteEye of in The 9/11 Forum. Very early stages but some properties of ROOSD propagation have been identified by careful observation.


Ozeco: ".we used to maintain a clear distinction between genuine sceptics who doubted the "no demolition" case and "truthers" or "CTs". So there were three camps back in 2007 when I first became involved in 9/11 discussions."

I call them: Tweedle-dee, Tweedle-dum and "other".

Tweedle-dee and Tweedle-dum are very loud but they are not very smart.

Richard Gage is Tweedle-dee.


In my opinion the best part of the debate is done off stage by independent researchers.

Tweedle-dee and Tweedle-dum are just a side show, a (really big) distraction.

[Myriad]

Why are we not talking about the hole in the building and where the 250 massive steel columns disappeared to- and all simultaneously at that.


Because you asked about the upper block.

Now you're asking why I didn't abruptly change the subject? Because I rely on you for that. Specialization and division of labor promotes efficiency. I answer your questions, you abruptly change the subject. That's how it works, why change?

Respectfully,
Myriad

[Major_Tom]

Myriad, a "block" is a 2 or 3 dimensional object. There are no blocks in 1 dimension.


I thought we already agreed that the Bazant crush up, crush down equations of motion and the concept of crush down, then crush up are true only for a 1-D stick model based on propagation by buckling upwards or downwards from the initiation point?

Significant crush up cannot occur because the upwards force is insufficient to buckle the columns upward in the stick model as explained in BV.


Now the same thing applies to 3-D blocks (and to real buildings, too???)

[ozeco41]

I'm not sure how to take this aspect of Major Tom's theory. Maybe he has no claim at all, but he doesn't seem to rule out "a demolition team."

From what he posts his logic has not, at that stage, ruled out demolition.

In my own explanatory posts I routinely leave the option of demolition open until I have reached the stage where demolition can be ruled out. Call it "honesty in debate" or some such ethical scruple. I don't like presuming that which I have not shown if it is a central issue under contention. For brevity in debate I will often make assertions on secondary matters on the implied or explicit justification that I am prepared to give "proof" if called on.

So, for an example, "The initial collapse stage for the twin towers, the stage where the top block started to fall, resulted from some process weakening the structure in the impact zone. That process was either aircraft impact damage plus accumulated fire damage alone OR the same impact and fire damage PLUS assistance from demolition...."
...should not be read as me supporting demolition. I am simply leaving one option open because at that stage it is still a possibility of logic.

[Myriad]

Well, yeah. Bazant's best-case scenario for collapse arrest depends on the upper block remaining intact, so that all the impacts can be column-on-column and as much energy as possible can be absorbed in 3-hinge buckling of all the columns.

If the upper block falls apart, so does the best-case scenario -- making collapse arrest even less of a possibility.

Oops.


Myriad, a "block" is a 2 or 3 dimensional object. There are no blocks in 1 dimension.

I thought we already agreed that the Bazant crush up, crush down equations of motion and the concept of crush down, then crush up are true only for a 1-D stick model based on propagation by buckling upwards or downwards from the initiation point?

Significant crush up cannot occur because the upwards force is insufficient to buckle the columns upward in the stick model as explained in BV.

Now the same thing applies to 3-D blocks (and to real buildings, too???)


Since you started your post with my username, I get the impression that you were intending to reply to my post, but I don't see any connection at all between my post and your response.

Three-hinge buckling is definitely part of Bazant's collapse model, and three-hinge buckling definitely cannot take place in one dimension, so any claim to the effect that every aspect of Bazant's collapse model is limited to one dimension is clearly false. Does that help?

Respectfully,
Myriad

[beachnut]

... In my opinion the best part of the debate is done off stage by independent researchers.

Tweedle-dee and Tweedle-dum are just a side show, a (really big) distraction.
Are you tweedle-dum? The debate? lol, there is no CD, it is a delusion since you have no evidence. Yes the best place to debate the insanity of CD is off stage at some forum where nonsense is weighed equally with reality.

8 years of no evidence and you think you can debate CD. And you are serious. Have you dropped the insane CD claims yet? No.

The best you can do is attack Bazant's model. Any plans for attending engineering school?

CD was ruled out on 911, anyone who can't figure that out lacks knowledge, can't process evidence, lacks logical thinking skills, and the ability to leave their paranoid conspiracy theory past behind.

[leftysergeant]

Myriad, a "block" is a 2 or 3 dimensional object. There are no blocks in 1 dimension.


I thought we already agreed that the Bazant crush up, crush down equations of motion and the concept of crush down, then crush up are true only for a 1-D stick model based on propagation by buckling upwards or downwards from the initiation point?

Significant crush up cannot occur because the upwards force is insufficient to buckle the columns upward...

It isn't like the bottom is supposed to act like a rocket driving upward at the falling block. The idea behind explosive CD and verinage is that the top part, once disconnected from the foundation and dropped with some force, will be unable to support its own weight, thus will crumble as it comes into contact with the ground.

For what you claim to be true, the upper block must still be capabable of standing as a complete structure, after having dropped the distance described. Clearly, it is not.

As far as I can see, you are arguing for survival of most building in explosive CD or verinage.

[carlitos]

From what he posts his logic has not, at that stage, ruled out demolition.

In my own explanatory posts I routinely leave the option of demolition open until I have reached the stage where demolition can be ruled out. Call it "honesty in debate" or some such ethical scruple. I don't like presuming that which I have not shown if it is a central issue under contention. For brevity in debate I will often make assertions on secondary matters on the implied or explicit justification that I am prepared to give "proof" if called on.

So, for an example, "The initial collapse stage for the twin towers, the stage where the top block started to fall, resulted from some process weakening the structure in the impact zone. That process was either aircraft impact damage plus accumulated fire damage alone OR the same impact and fire damage PLUS assistance from demolition...."
...should not be read as me supporting demolition. I am simply leaving one option open because at that stage it is still a possibility of logic.

It's a fair point, but given the massive amount of evidence against demolition, at what point is it dishonest to include the possibility? These analyses aren't being done in a vacuum; they are being done in the real world where we know that bombs make noise and thermite burns gravitationally, etc.

[bill smith]

Because you asked about the upper block.

Now you're asking why I didn't abruptly change the subject? Because I rely on you for that. Specialization and division of labor promotes efficiency. I answer your questions, you abruptly change the subject. That's how it works, why change?

Respectfully,
Myriad

I was just making the point that Bazant has nothing to do with the real collapse event of WTC1. You are in full agreement I take it ?

We can therefore dispense with Bazant altogether ? Or if not maybe you can explain the value and significance of Bazant's work as it relates to the authentic event.

To be frank Myriad I can feel Bazant fading into insignificance- finally..

[leftysergeant]

I was just making the point that Bazant has nothing to do with the real collapse event of WTC1. You are in full agreement I take it ?

His math was right, he just went a little off track on the sequence of crush-up, crush down.

We can therefore dispense with Bazant altogether ? Or if not maybe you can explain the value and significance of Bazant's work as it relates to the authentic event.

Bazant demonstrated that the energy to do the job was available. Verinage proves that what he describes is the way that buioldings will, generally, perform.

Gage is left looking like a moron as the Balzac-Vitry structure crushes itself to oblivion exactly as Bazant describes.

[Myriad]

We can therefore dispense with Bazant altogether?


Hey, no one can stop you from dispensing with anything altogether. You can dispense with food, you can dispense with arithmetic, you can dispense with words, you can dispense with gravity, you can dispense with sight, you can dispense with traffic laws, you can dispense with safety warnings on power tools, you can dispense with breathing, you can dispense with truth, you can dispense with sanity.

You can even dispense with all the consequences of dispensing with these things.

What you cannot do is prevent those consequences from occurring.

Respectfully,
Myriad

[femr2]

Bazant demonstrated that the energy to do the job was available.
Agreed.

Verinage proves that what he describes is the way that buildings will, generally, perform.
Ah. Not agreed. Verinage is a very specific case, not borne out by generalised building performance. The numerous failed demolitions are case-in-point there. Like these...
eiAdQLQQGR8
or
xD126r9ihaw

Given the thread purpose, it's pertinent to make this point.

[bill smith]

Hey, no one can stop you from dispensing with anything altogether. You can dispense with food, you can dispense with arithmetic, you can dispense with words, you can dispense with gravity, you can dispense with sight, you can dispense with traffic laws, you can dispense with safety warnings on power tools, you can dispense with breathing, you can dispense with truth, you can dispense with sanity.

You can even dispense with all the consequences of dispensing with these things.

What you cannot do is prevent those consequences from occurring.

Respectfully,
Myriad

But you missed out the consequences of dispensing with Bazant....if there are in fact any. .

[bill smith]

His math was right, he just went a little off track on the sequence of crush-up, crush down.



Bazant demonstrated that the energy to do the job was available. Verinage proves that what he describes is the way that buioldings will, generally, perform.

Gage is left looking like a moron as the Balzac-Vitry structure crushes itself to oblivion exactly as Bazant describes.


Hmmm.........

[ozeco41]

It's a fair point, but given the massive amount of evidence against demolition, at what point is it dishonest to include the possibility? These analyses aren't being done in a vacuum; they are being done in the real world where we know that bombs make noise and thermite burns gravitationally, etc.

It depends entirely on the context of the specific discussion and the scope of that discussion and whatever stage my discussion with the other party has reached on the topic.

In the general situation if I was debating with a person who was possible an interested sceptic and who had made some valid points which fell within the whole context of the "Demolition or not?" topic then I would feel obliged to be rigorous in laying out my explanation. I could foreshadow my long established opinion as to "no demolition" but in laying out the logic and any necessary supporting evidence I would not be entitled to presume the "no demolition" outcome until I had laid out the case to support that conclusion.

In this current thread the global topic is "applicability of Bazant's model to the real world"

A sub set contained within the global scope of that topic is "applicability of Bazant to WTC 1, 2, 7" and my comments are further limited to WTC 1 & 2.

My position has been stated as accepting Bazant as globally valid i.e. there was more than enough energy to sustain the global collapse of each of the twin towers. I have stated reasons why I do not regard Bazant as valid if taken further into detail for WTC1 & 2 - irrespective of Bazant' general applicability to other structures.

Major_Tom has pointed out that Bazant applies to the "global collapse" stage of WTC1 & 2 collapses but not to the "initial collapses" (My terminology used to state M_T's position)

He and I (and others) have explored some details of our differing approaches to the WTC global collapse.

M_T has indicated that the "initial collapse" is outside the scope of Bazant's work. We have not discussed "initial collapse". And it falls outside the scope of this thread. However, explaining briefly, although I hold that "initial collapse" occurred without demolition, we have not reached that stage of logic in our discussions. The point therefore is on the table till our discussions progress. And that includes if our discussion progress - they may well not but that does not change the fact that he and I have not discussed "initial collapse" nor does it preclude me from saying to him "I've explained this many times previously - here are the links".

I am aware that most of the preceding is no longer current practice on threads such as these. "We" seem to have polarised into a two camp polarised situation between "truthers" and "debunkers" - both sides having several rude names of denigration.

I recall that "we" used to have three parties - genuine (or apparently genuine) sceptics being the third group. I still tend to give benefit of doubt and accept positions which oppose mine as being possibly genuinely held sceptic positions.

The question of "...given the massive amount of evidence against demolition, at what point is it dishonest to include the possibility?" ...does not arise in the situations I have described. It would arise if I, or a person like me, started to advocate "demolition" against my better professional judgement. Doing so seriously (not in fun/irony/poe) would be dishonest.

I leave it to you to muse on how that principle applies to Richard Gage and the other high profile claimants pro demolition.

[bill smith]

It's beginning to look as though it's not only Bazant that is feeling the chill . Even NIST are being overridden and explosives are back on the table.

We are certainly making progress.

[ozeco41]

It's beginning to look as though it's not only Bazant that is feeling the chill . Even NIST are being overridden and explosives are back on the table.

We are certainly making progress.
Wishful thinking there Bill on your three points:
1) "We" are all agreed that Bazant was right - there was sufficient energy to complete the global collapse of the twin towers.
2) "We" are all agreed that NIST was right - no demolition of the towers AND once collapse started "global collapse was inevitable" AND
3) recent discussions here show that the only place explosives are on the table is where honest professionals explain the "no demolition" case to genuine sceptics.

And "we" don't need to make progress but we have. There are few genuine sceptics still enquiring about truther rubbish.

...and few, if any, genuine truthers still posting...

[pgimeno]

I was just making the point that Bazant has nothing to do with the real collapse event of WTC1.

You were just making a wrong point. The real collapse event of WTC1 is one of the many collapse scenarios that Bazant proved would be unstoppable once initiated.

And please stop your latest derailing.

[pgimeno]

Agreed.


Ah. Not agreed. Verinage is a very specific case, not borne out by generalised building performance. The numerous failed demolitions are case-in-point there. Like these...
eiAdQLQQGR8
or
xD126r9ihaw

Given the thread purpose, it's pertinent to make this point.

Both failed demolitions prove that in neither case was the KE enough to cause failure. Both are arrested at the point where the explosives were not used. Not very useful for any purpose related to this thread.

[ozeco41]

Both failed demolitions prove that in neither case was the KE enough to cause failure. Both are arrested at the point where the explosives were not used. Not very useful for any purpose related to this thread.
In fact BOTH cases could have benefited from a Bazant Model assessment before they tried and failed. :):D


Remembering that Bazant's Model is conservative, and ultra conservative for steel structures similar to the WTC towers. I am unsure as to whether it would be equally as conservative for those two buildings. :rolleyes:

[leftysergeant]

The failed buildings appear to be rather robustly-built structures and were not adequately pre-weakened., nor do they seem to have dropped far enough to develop sufficient momentum

[ozeco41]

The failed buildings appear to be rather robustly-built structures and were not adequately pre-weakened., nor do they seem to have dropped far enough to develop sufficient momentum
Yes. Or in pgimeno's words "not enough KE"

[leftysergeant]

Yes. Or in pgimeno's words "not enough KE":boggled:

You may have noticed that I am not an engineer.

But then, I don't think you need to be an engineer to see through most twoofishness. Just trying to put it into my own native language and hoping that that makes it accessible to the other side.

Apparently, that is still not dumbed-down enough for some people.

[ozeco41]

:boggled:

You may have noticed that I am not an engineer......you are quite switched on as an obviously practical thinking person. And it doesn't need any more than that to understand the basics. Dealing with the more technical stuff such as "Where is the line where Bazant ceases to apply to WTC1 & 2?" starts to get into the areas where many "run of the mill" engineers would fumble.

...But then, I don't think you need to be an engineer to see through most twoofishness.... ..agreed wholeheartedly Just trying to put it into my own native language and hoping that that makes it accessible to the other side.

Apparently, that is still not dumbed-down enough for some people...a valiant and worthwhile goal. Setting aside my several recent posts here which have touched on some esoteric matters I usually write with the "interested and reasonably intelligent non-engineer" as the target.

So keep up the good work BUT don't lose sight of "there's none so blind as those who will not see..."

[Major_Tom]

Leftysergeant, verinage demos do not show that the crush down phase happens before the crush up phase as Bazant claims for his 1-D stick model.

We find many different crush up, crush down ratios in verinage demos, but I haven's seen a single case of crush down before crush up, have you?

We notice close to a 1:1 crush up crush down ratio in the Balzac demo. A 1:1 ratio makes sense, but that is not what Bazant claims. He claims crush down, then crush up.

>>>>>>>>>>>>>>>>>>>>

Why is it an extreme stretch to apply the Bazant 1-D stick model based on column buckling for up and down propagation to 3-D objects and real buildings?

Because Bazant justifies very little early crush up based on the fact that there is insufficient upward force to buckle the columns upwards.

Hence the concept of "crush down, then crush up".

Now let's use the same logic for a real building: Does any thinking person believe that the upper columns will ride on the debris zone B, which provides insufficient upward force to prevent the columns from collectively buckling upward, hence the upper portion of the building will remain largely undamaged?

Can you see how absurd it is to claim that no upward buckling saves the upper portion of a real building from crush-up?

In a steel building with concrete and metal floor slabs, the upper columns may just spear through the flooring with ease. There are many possiilities, but their buckling strength is certainly not going to save the upper portion from serious, serious damage.

WHen you apply the Bazant 1-D stick model and the concept of crush down, then crush up to real buildings, you are assuming that the column strength and it's resistance to buckling upwards will save the upper portion from early crush up.

That is obviously crazy, so why do so many people do it, including R Mackey and Myriad?

I think it is because people do not realize that the Bazant argument for no early crush up depends on the upward force not exceeding the upper column yield strength (in BV and BL).

They forget on what the argument depends, and try to apply it to the 3-D world anyway.

[carlitos]

Since you started your post with my username, I get the impression that you were intending to reply to my post, but I don't see any connection at all between my post and your response.

Three-hinge buckling is definitely part of Bazant's collapse model, and three-hinge buckling definitely cannot take place in one dimension, so any claim to the effect that every aspect of Bazant's collapse model is limited to one dimension is clearly false. Does that help?

Respectfully,
Myriad

Leftysergeant, verinage demos do not show that the crush down phase happens before the crush up phase as Bazant claims for his 1-D stick model.

...

Why is it an extreme stretch to apply the Bazant 1-D stick model based on column buckling for up and down propagation to 3-D objects and real buildings?

...

WHen you apply the Bazant 1-D stick model and the concept of crush down, then crush up to real buildings, you are assuming that the column strength and it's resistance to buckling upwards will save the upper portion from early crush up.

That is obviously crazy, so why do so many people do it, including R Mackey and Myriad?

I think it is because people do not realize that the Bazant argument for no early crush up depends on the upward force not exceeding the upper column yield strength (in BV and BL).

They forget on what the argument depends, and try to apply it to the 3-D world anyway.

Can someone clarify the obvious disconnect above, between three hinge buckling and "1-D sticks." Thank you in advance.

[Major_Tom]

The truth is many people apply the concept of crush down, then crush up to 3-D situations. Consider a great example from BLGB. Bazant writes:

From BLGB, pg 894,5: “Generalization of Differential Equation
of Progressive Collapse

The gravity-driven progressive collapse of a tower consists of two
phases—the crush-down, followed by crush-up (Fig. 2 bottom)—
each of which is governed by a different differential equation
(Bažant and Verdure 2007, 312–313). During the crush-down
phase, the falling upper part of the tower (C in Fig. 2 bottom),
having a compacted layer of debris at its bottom (zone B), crushes
the lower part (zone A) with negligible damage to itself. During
the crush-up, the moving upper part C of the tower is crushed at
the bottom by the compacted debris B resting on the ground.
The fact that the crush-up of entire stories cannot occur simultaneously
with the crush-down is demonstrated by the condition
of the dynamic equilibrium of compacted layer B, along with an
estimate of the inertia force of this layer due to vertical deceleration
or acceleration; [see Eq. (10) and Fig. 2(f) of Bažant and
Verdure (2007)]. This previous demonstration, however, was only
approximate since it did not take into account the variation of
crushing forces Fc and Fc ‘ during the collapse of a story. An accurate
analysis of simultaneous (deterministic) crush-up and
crush-down is reported in Bažant and Le (2008) and is reviewed
in the Appendix, where the differential equations and the initial
conditions for a two-way crush are formulated. It is found that,
immediately after the first critical story collapses, crush fronts
will propagate both downward and upward. However, the
crush-up front will advance into the overlying story by only about
1% of its original height h and then stop. Consequently, the effect
of the initial two-way crush is imperceptible and the original hypothesis
that the crush-down and crush-up cannot occur simultaneously
is almost exact.”

http://www.sharpprintinginc.com/911/images/photoalbum/13/Bazant_crush_up__down.jpg
Fig. 2. (Top)Scenario of collapse; (bottom) crush-down and crush-up phases of collapse; (A) intact stationary (lower) part; (B) dense layer of crushed debris; and (C) intact moving (upper) part



Is Bazant applying his crush down, then crush up model to the WTC towers in this quote and in the figures, or is he only describing and and illustrating the theoretical scenario best able to survive as an extreme case (which we do not expect to match the actual towers)?

I see no mention of this only as a theoretical case most optimal for survival. Are we to assume so?

He never refers to the diagrams as only an extreme, theoretical case based on assumptions most optimal for survival.

Myriad or others, should we assume this is only the case most optimal for survival?

[Major_Tom]

When Bazant says "The gravity-driven progressive collapse of a tower consists of two
phases—the crush-down, followed by crush-up"


Does he really mean "The gravity-driven progressive collapse of a theoretical scenario based on successive upward or downward axial impacts which represent the case most optimal for survival and does not represent the actual behavior of the towers consists of two phases—the crush-down, followed by crush-up"

Is that what he really means? No it is not.

[Grizzly Bear]

Is Bazant applying his crush down, then crush up model to the WTC towers in this quote and in the figures, or is he only describing and and illustrating the theoretical scenario best able to survive as an extreme case (which we do not expect to match the actual towers)?

I see no mention of this only as a theoretical case most optimal for survival. Are we to assume so?

He never refers to the diagrams as only an extreme, theoretical case based on assumptions most optimal for survival.

Just to point out...

http://www.civil.northwestern.edu/people/bazant/PDFs/Papers/405.pdf
This paper presents a simplified approximate analysis of the overall collapse of the towers of World Trade Center in New York on September 11, 2001. The analysis shows that if prolonged heating caused the majority of columns of a single floor to lose their load carrying capacity, the whole tower was doomed.

For our purpose, we may assume that all the impact forces go into the columns and are distributed among them equally. Unlikely though such a distribution may be, it is nevertheless the most optimistic hypothesis to make because the resistance of the building to the impact is, for such a distribution, the highest. If the building is found to fail under a uniform distribution of the impact forces, it would fail under any other distribution. According to this hypothesis, one may estimate that C'71 GN/m ~due to unavailability of precise data, an approximate design of column cross sections had to be carried out for this purpose.

More prominent posters such as Tony Szamboti give me no indication of having acknowledged this, and frankly I'm not sure how the author of that paper could have been any more clear. This is in the first page of the paper... It's rather difficult to overlook if you carefully read it.

[Major_Tom]

Grizzly Bear, your quote if from BZ in 2002. Different argument, different paper. You people cannot be that stupid.

[DGM]

Grizzly Bear, your quote if from BZ in 2002. Different argument, different paper. You people cannot be that stupid.
Sure we can, That's why there's all the fuss in the engineering world.


:rolleyes:

[Major_Tom]

Dave Rogers provides another example of applying the concept of crush down, then crush up to blocks and buildings here:

"If you were to actually read Bazant's papers for comprehension, rather than deciding what strawman you want to attribute to them, you would see that the analysis predicts that crush-up and crush-down will initially both occur, but that the rate of crush-up will quickly decay to zero while the rate of crush-down increases. This is an idealised case, and the presence of damage to the structure above or below the collapse initiation zone will modify the precise amount of crush-up initially observed, but at no point is Bazant claiming that there is no crush-up until crush-down is complete; he's determining that a very small amount of initial crush-up occurs, but that it self-terminates until the upper block contacts the ground. As a result, a small proportion of the rubble comes from the upper block, and the majority from the lower."

From this post http://forums.randi.org/showpost.php?p=5941193&postcount=92

We once again have an upper block being destroyed by crush up only after it hits the earth.

The upper block once again preserved by the strength of it's columns and the magic zone B. Bazant proved it in BL, no?

with no awareness of the irony, Dave concluded:

"Funnily enough, no, the rest of us can't see that, because the dust ejected by the collapse obscures vision of the upper block part way into the collapse. Since we can't tell what happens to things we can't see, we can either make up something that fits our prejudices or model the physics of the collapse mathematically and draw provisional conclusions. The first approach seems to be working very nicely for you, to the extent that you've convinced yourself you can see something that's hidden in a dust cloud. For the rest of us, we'd rather start from what we can see then decide on a conclusion, than start from a conclusion then decide what we can see."

That part about the upper block was made up.

[DGM]

Major Tom:
In all seriousness, Why do you think the engineering (as applied to buildings) world is not paying any attention to you?

I don't think I can make this anymore plain.

[pgimeno]

Grizzly Bear, your quote if from BZ in 2002. Different argument, different paper. You people cannot be that stupid.

Oh! So are you arguing that Bazant became dumber as he published more papers?

A good idea is to read the OP more carefully. Your examples are bogus.

There is room for opinion on whether, how and why a model can be applied to the real world, but doing so is in not necessarily a mistake. That is what the OP is about. You are claiming that the model can't be applied to the real world for extracting certain aspects out of it, without providing any valid reason. Your reasoning is that it is invalid because it doesn't match certain aspects of the real collapse more closely. It's like claiming that Newtonian physics are invalid and can't be applied to the real world, because they don't match with relativistic effects.

And that makes no sense.

[Grizzly Bear]

Grizzly Bear, your quote if from BZ in 2002. Different argument, different paper. You people cannot be that stupid.

Please review his subsequent papers as they either reference his original 2001 paper or state succicntly the purpose of the model:

http://www.civil.northwestern.edu/people/bazant/PDFs/Papers/00%20WTC%20Collapse%20-%20What%20Did%20&%20Did%20Not%20Cause%20It.pdf
Abstract: Previous analysis of progressive collapse showed that gravity alone suffices to explain the overall collapse of the World Trade Center (WTC) towers.

To explain the collapse, it was proposed (on September 13, 2001; Baˇzant 2001; Baˇzant and Zhou 2002) that viscoplastic buckling of heated and overloaded columns caused the top part of tower to fall through the height of at least one story, and then shown that the kinetic energy of the impact on the lower part must have exceeded the energy absorption capacity of the lower part by an order of magnitude.

http://www.civil.northwestern.edu/people/bazant/PDFs/Papers/466.pdf

A simplified one-dimensional analytical solution of the collapse front propagation will be presented. It will be shown how this solution can be used to determine the energy absorption capability of individual stories if the motion history is precisely recorded.

In broad terms, this scenario was proposed by Bažant 2001, and Bažant and Zhou 2002a,b on the basis of simplified analysis relying solely on energy considerations.

There is no indication that Bazant is using anything other than a limiting case model, no assumptions about this are necessary. He's makes it clear - usually within the first page or two - what he was setting up. It would be relevant for you to be reminded that you asked for clarification on whether or not Bazant's crush up/down model was in fact, a limiting case - the answer to which is yes it was. And yes he made it clear it was. "Different argument, different paper"? Sorry, no... reread what you asked. I gave you the answer.


Such a model may not represent what happened in reality, but it is applicable providing the scope of it is explained properly.

[pgimeno]

Grizzly Bear, please read the OP. It deals precisely with where and how Bazant et al are applying the model to the real world collapse in order to extract some conclusions out of it, and not as a limiting case.

[Grizzly Bear]

Grizzly Bear, please read the OP. It deals precisely with where and how Bazant et al are applying the model to the real world collapse in order to extract some conclusions out of it, and not as a limiting case.

Editing

[leftysergeant]

All the videos I have seen of verinage show the upper block disintegrating more slowly than the lower. There were, for example, more floors above the break in Balzac-Vitry, but the roof is seen to be in tact until nearly the last seconds.

The upper floors of the twin towers acted somewhat differently because they were more fragile and had that huge spindle shoved up the middle. The joints in the upper core columns were probably badly compromised already because they were more badly skewed and had most of the stress of the hat trusses twisting them. Somewherte here we have videos of some buildings in Mecca being pulled. The taller, thinner buildings begin to fold as they tip over, just as did the south tower.

The crush-down, crush-up model generally apllies. The rate is just a little different in varying types of construction. Crush-up appears to occur when resistance in the lower block reaches a certain threshhold. That occurred very early in the north tower because the lower portion was not as badly compromised, thus more resistant, than the top. The building still had no chance of survival because by the time crush-up was cpmpleted, enough debris had accumulated that it might as well have been an undamaged building falling on the lower floors. Those hat trusses were freaking MASSIVE compared to the rest of the steel structures that were falling.

[ozeco41]

... Those hat trusses were freaking MASSIVE compared to the rest of the steel structures that were falling.
Even without the maths, had the top block hung up on the core I would be pretty confident that the outer columns and floors of the top block would have stayed in place hanging off the hat truss.

[bill smith]

Wishful thinking there Bill on your three points:
1) "We" are all agreed that Bazant was right - there was sufficient energy to complete the global collapse of the twin towers.
2) "We" are all agreed that NIST was right - no demolition of the towers AND once collapse started "global collapse was inevitable" AND
3) recent discussions here show that the only place explosives are on the table is where honest professionals explain the "no demolition" case to genuine sceptics.

And "we" don't need to make progress but we have. There are few genuine sceptics still enquiring about truther rubbish.

...and few, if any, genuine truthers still posting...

Is that all that Bazant brought then ? His theory that there was enough energy in a short drop of the top one-tenth of the building to crush the other nine-tenths of the structure down flat on the ground ? If so what a horrible waste of time and space Bazant has been.

Your number two point can be ignored as completely absurd.

Recent discussions here are serving to put Bazant where he should be put. Firmly on the rearmost back burner if not altogether out with the trash.

[leftysergeant]

Is that all that Bazant brought then ? His theory that there was enough energy in a short drop of the top one-tenth of the building to crush the other nine-tenths of the structure down flat on the ground ? If so what a horrible waste of time and space Bazant has been.

It strikes down little Dickie's argument that you can't break a big box by dropping a small one on it.

[Major_Tom]

I've been trying to figure out why people associate a crush up, crush down model with the argument in BZ (2002). The crush up crush down model was published in 2007 in the paper by Bazant and Verdure (2007).

When I use the phrase "Bazant model", I think most of the posters have no idea what I am referring to, so to clear up confusion let's think of there being 2 different Bazant models.


In BZ, there is a "model" used for the analysis of inelastic energy dissipation of a single story. THIS IS NOT A CRUSH UP, CRUSH DOWN MODEL. It only analyzes a single collision after a 12 ft fall to see if the resulting kinetic energy can be totally absorbed by the underlying columns. Not much of a surprise that it cannot.


In BV (2007) there is a crush up, crush down progressive collapse model presented in the form of separate crush down and crush up equations of motion. THIS IS A CRUSH DOWN, CRUSH UP MODEL.



There is no crush up, crush down progressive collapse model in BZ. Only a single perfect axial collision between columns is analyzed.

I began posting on this subject in May and it is now September, yet many people still cannot tell the difference between BZ single collision analysis and the crush up, crush down model given in BV (2007).





Hint: THE CRUSH UP, CRUSH DOWN MODEL IS FIRST EXPLAINED IN BV (2007), IT IS REFINED IN BL (2008) AND APPLIED TO THE WTC TOWERS IN BL (2008) AND BLGB (2008).

IT DID NOT EXIST IN 2002 SO PLEASE DO NOT REFER TO BZ QUOTES WHEN DISCUSSING IT.

[Major_Tom]

Posters like Ozeco and Leftysergeant are referring to the energetics argument in BZ. That is fine and I have no argument with them. The OOS collapse propagation model suggests a path of least resistance down the OOS regions, so I am obviously not arguing for collapse arrest.


Leftysergeant, Bazant's crush down then crush up model presented in BV (2007) predicts that crush down must run to completion before significant crush up can occur.

Not one verinage demo that I have observed does this. We see different crush up, crush down ratios but no examples of complete crush down before crush up. It is not the question of energetics but in the order of crush down and crush up that matters whan discussing BV, BL and BLGB.

[Major_Tom]

BZ is not useful for matching or predicting real observable features of the WTC collapses, but the arguments in BV, BL and BLGB can be used to match or predict specific features of the collapsing towers, and Bazant seems to do just that in BL and BLGB.

Let's keep the BZ "model" separate from the BV crush up, crush down progressive collapse model published in 2007 or you won't understand what Bazant's progressive collapse model is.

[bill smith]

So the 2007 model does not act as a continuation or oart 2 of the 2002 model ?

You mean that you cannot describe the two together as ' the Bazant model '? Why not ?

[Major_Tom]

Because the BZ (2002) paper discusses the energetics of the collapse of a single story with conditions most favorable for survival.

In BV (2007), Bazant tries to derive crush down and crush up equations which can be used to measure the roofline and crush front motion of real buildings if 4 simplifying assumptions are met.

He applies a modified form of these same equations to the towers in BLGB and tries to match the actual roofline descent of WTC1 with the model in BLGB.

[bill smith]

Because the BZ (2002) paper discusses the energetics of the collapse of a single story with conditions most favorable for survival.

In BV (2007), Bazant tries to derive crush down and crush up equations which can be used to measure the roofline and crush front motion of real buildings if 4 simplifying assumptions are met.

He applies a modified form of these same equations to the towers in BLGB and tries to match the actual roofline descent of WTC1 with the model in BLGB.

So the two, BZ and BV cannot be be connected and seen collectively as 'the Bazant Model' ? (Even loosely ?) That seems kind of silly of Bazant doesn't it ? A lost opportunity to make a complete contiguous collapse sequence.

[leftysergeant]

Any way you slice it, Bazant is still closer to the absolute truth than little Dickie Gage will ever come.

[bill smith]

Any way you slice it, Bazant is still closer to the absolute truth than little Dickie Gage will ever come.

Bazant is finished. He was only ever a distraction anyway. Though I would be happy for Major Tom or Femr2 to explain why we have been arguing Bazant and mixing up his hypotheses (like the ridiculous rubble layer) with the real event for so long.

The REAL problem:-
What exactly happened to the 250 massive columns connecting the top and bottom parts.allowing the top part to go into freefall in the first place.

[leftysergeant]

The REAL problem:-
What exactly happened to the 250 massive columns connecting the top and bottom parts.allowing the top part to go into freefall in the first place.

They got knocked catawampus by a hundred-ton hammer and their crystal structure was compromised by extreme heat and joints were broken by thermal creep.

There was never a sound that could indicate explosive demolitions, nor any sign of damage such as would be associated with any form of thermite of which I have any knowledge.

(Nor have any of the thermite believers come near to explaining why they would put kaolin in a thermite charge.)

[bill smith]

They got knocked catawampus by a hundred-ton hammer and their crystal structure was compromised by extreme heat and joints were broken by thermal creep.

There was never a sound that could indicate explosive demolitions, nor any sign of damage such as would be associated with any form of thermite of which I have any knowledge.

(Nor have any of the thermite believers come near to explaining why they would put kaolin in a thermite charge.)

That is ludicrous Sarge, those 250 columns were not heated anything like evenly and would therefore have failed unevenly causing the top part to visibly lean before falling. (Like WTC2 did for instance)

[leftysergeant]

That is ludicrous Sarge, those 250 columns were not heated anything like evenly and would therefore have failed unevenly causing the top part to visibly lean before falling. (Like WTC2 did for instance)

Neither of them fell straight down.

[bill smith]

Neither of them fell straight down.

Well....maybe we better not drift too far off topic Sarge.

[leftysergeant]

Well....maybe we better not drift too far off topic Sarge.

They all started falling crooked and straightened out as collapse progessed.

More consistant with Bazant than with little Dickie.

[ozeco41]

So the two, BZ and BV cannot be be connected and seen collectively as 'the Bazant Model' ? (Even loosely ?) That seems kind of silly of Bazant doesn't it ? A lost opportunity to make a complete contiguous collapse sequence.

Bill you persist in trying to "black or white" the issue.

It is really quite a simple question of how far the grey goes and how far can Bazants valid work be extended into the grey for the WTC Towers where it does not fit with accuracy.

BZ 2002 said "there was more than enough energy to ensure that the collapse of the twin towers progressed to completion without stopping half way (AND without needing any demolition)" That claim was true. It remains true. BZ even assumed the worst case - that when the top block started to fall it fell a distance - he initially said one floor but modified that so say one metre or less. Then the columns in the top block landed on those of the lower bit so that the top bit of those columns all lined up with the columns in the bottom block. Call that point "A". Even with the strength of those columns allowed for there was still enough energy for complete collapse and without demolition. (Note and remember that his estimate of "overload" said thirty one (31) times.)

Now the WTC Twin Towers did not fall with top column parts sitting on bottom column parts. So Bazant's conservative assumptions proved the towers would collapse and without need of explosives/thermate/laser beams from space etc. And that was his main purpose back then in late 2001 early 2002.

He used a conservative model which was more conservative for the Twin Towers than it would be for most other buildings because of the tube in tube construction and the manner that collapse of twin towers was started.

Then Bazant ad various colleagues wanted to develop a general model for building progressive collapse. They developed the model using concepts of "crush up/crush down" and supported those concepts using a lot of complicated looking mathematics and confusing language. Typical academics. However they never explicitly (as far as I can see) moved away from the original assumption of axial contact between columns.

So the model is not accurate in detail for WTC Towers as far as I can see. Recent discussions have been about "how far you can take it" given the base assumptions. You can take it a long way for general buildings which are not "tube-in-tube" like the twin towers. Not so far for the WTC Twin Towers.

I have no real interest in how far to take Bazant and remain valid. I have no interest in the academic competition sideline of countering with peer reviewed papers. I am satisfied by simple observation of the video and picture evidence that the progressive global collapse of the Twin Towers was inevitable and without demolition assistance.

Bazant got 31 times overload. Just for interest when I first answered the question back in early 2008 I guestimated it was in the order of 20 times to 50 times overload. Without the complicated maths.

Now recall my suggestion to "remember point A". The "jolt" which Bazant's conservative model predicted as the top block struck at "point A"? That is the "Missing Jolt" which Tony Szamboti went looking for in his paper of that name. He took Bazant's worst case as gospel. But the WTC Twin Towers did not start to collapse by the worst case of Bazant's model. Hence the futility of Tony's search for a jolt which wasn't needed. It wasn't there because it wasn't needed.

[ozeco41]

They all started falling crooked and straightened out as collapse progessed.

More consistant with Bazant than with little Dickie....or Heiwa. ;)

The box on box models are pure dishonesty (or incompetence).

The real contact of the twin towers was more like two parts of a cut wire basket coming into contact. Think about that. And, yes, very thick wires. :D

[bill smith]

Bill you persist in trying to "black or white" the issue.

It is really quite a simple question of how far the grey goes and how far can Bazants valid work be extended into the grey for the WTC Towers where it does not fit with accuracy.

BZ 2002 said "there was more than enough energy to ensure that the collapse of the twin towers progressed to completion without stopping half way (AND without needing any demolition)" That claim was true. It remains true. BZ even assumed the worst case - that when the top block started to fall it fell a distance - he initially said one floor but modified that so say one metre or less. Then the columns in the top block landed on those of the lower bit so that the top bit of those columns all lined up with the columns in the bottom block. Call that point "A". Even with the strength of those columns allowed for there was still enough energy for complete collapse and without demolition. (Note and remember that his estimate of "overload" said thirty one (31) times.)

Now the WTC Twin Towers did not fall with top column parts sitting on bottom column parts. So Bazant's conservative assumptions proved the towers would collapse and without need of explosives/thermate/laser beams from space etc. And that was his main purpose back then in late 2001 early 2002.

He used a conservative model which was more conservative for the Twin Towers than it would be for most other buildings because of the tube in tube construction and the manner that collapse of twin towers was started.

Then Bazant ad various colleagues wanted to develop a general model for building progressive collapse. They developed the model using concepts of "crush up/crush down" and supported those concepts using a lot of complicated looking mathematics and confusing language. Typical academics. However they never explicitly (as far as I can see) moved away from the original assumption of axial contact between columns.

So the model is not accurate in detail for WTC Towers as far as I can see. Recent discussions have been about "how far you can take it" given the base assumptions. You can take it a long way for general buildings which are not "tube-in-tube" like the twin towers. Not so far for the WTC Twin Towers.

I have no real interest in how far to take Bazant and remain valid. I have no interest in the academic competition sideline of countering with peer reviewed papers. I am satisfied by simple observation of the video and picture evidence that the progressive global collapse of the Twin Towers was inevitable and without demolition assistance.

Bazant got 31 times overload. Just for interest when I first answered the question back in early 2008 I guestimated it was in the order of 20 times to 50 times overload. Without the complicated maths.

Now recall my suggestion to "remember point A". The "jolt" which Bazant's conservative model predicted as the top block struck at "point A"? That is the "Missing Jolt" which Tony Szamboti went looking for in his paper of that name. He took Bazant's worst case as gospel. But the WTC Twin Towers did not start to collapse by the worst case of Bazant's model. Hence the futility of Tony's search for a jolt which wasn't needed. It wasn't there because it wasn't needed.

In the part I have highlighted is it assumed that the upper columns remain in contact with the lower columns all the way down or would they slip off ? For the purposes of BZ and BV xombined ?

[ozeco41]

In the part I have highlighted is it assumed that the upper columns remain in contact with the lower columns all the way down or would they slip off ? For the purposes of BZ and BV xombined ?

BZ has top block falling inside lower tower tube once the global collapse is under way. (See Figure 1, Stage 5) and Bazant's comments:...the upper part is partly wedged within the emptied framed tube of the lower part, pushing the walls of the framed tube apart ͑Fig. 1, stage 5. Although each of these mechanisms can be shown to lead to total collapse, a combination of the last two seems more realistic ͓the reason: multistory pieces of the framed tube, with nearly straight boundaries apparently corresponding to plastic hinge lines causing buckles on the framed tube wall, were photographed falling down...

[Major_Tom]

Ozeco post #128: "Then Bazant ad various colleagues wanted to develop a general model for building progressive collapse. They developed the model using concepts of "crush up/crush down" and supported those concepts using a lot of complicated looking mathematics and confusing language. Typical academics. However they never explicitly (as far as I can see) moved away from the original assumption of axial contact between columns."

That is correct. In BV they derive crush up and crush down equations of motion based on successive upward and/or downward axial impacts. The concept of "crush down before significant crush up" was introduced in that paper. Almost nobody seemed to notice that the justification for no significant early crush up is that there is insufficient upwards force to buckle columns in the up direction.

The concept of crush down, then crush up is just a math trick, the result of an up-down 1-D successive axial impact model.

It is not a property of real buildings and observation of verinage style demos have yet to produce one actual example to my knowledge.

Then the strangest thing happened: People began to imagine that crush down then crush up was a real physical property of buildings. The quotes I provided by R Mackey and Dave Rogers show that even people with experience in physics could easily mistakenly believe that crush down before crush up, surviving upper blocks and magic zone Bs must exist for real buildings because Bazant proves it in BV and removes all doubt in BL.

You are the first person I have seen in this forum that recognizes this.

[pgimeno]

It is not a property of real buildings and observation of verinage style demos have yet to produce one actual example to my knowledge.

I think it is quite good an approximation, though. If you observe the crush front, you can see that the height from it to the top is more or less constant (the horizontal ejection of dust gives you a good estimation of where the crush front is). It's also evident that the visible part of the top of the building remains undamaged at all times during crush-down.

The red line superimposed here has the same height in all frames. Note that in the first frame, it doesn't reach the crush front, meaning that at least one more floor is crushed afterwards.

http://www.formauri.es/personal/pgimeno/xfiles/11-s/Balzac-Vitry-crush.gif

[pgimeno]

So the model is not accurate in detail for WTC Towers as far as I can see. Recent discussions have been about "how far you can take it" given the base assumptions. You can take it a long way for general buildings which are not "tube-in-tube" like the twin towers. Not so far for the WTC Twin Towers.

I have no real interest in how far to take Bazant and remain valid.

That question is interesting in view of the recent attacks to his work, though, as they are based on a wrong understanding of how models work. Also for people to understand that it's not necessary for the real world to behave exactly like the model in order for the model to be applicable to the real world. And also for people to understand that in spite of that, there are limits to that applicability itself.

When the limits of the model are not well known or understood, a comparison with the real world is helpful to see how good an approximation the model is. If the model gives a decent approximation of a certain parameter when compared to the real world, there is a basis to think that it can give approximate predictions in other real world cases. It may seem random, but in some cases having that approximation is better than having nothing at all.

In the real WTC case, the comparison of the model with the real world shows little difference in expected (by the model) vs. real collapse time, for example. That hints towards the utility of Bazant's model to estimate collapse times to a certain accuracy. Two specific and very similar cases are not enough to be convinced, but the material is now on the table for other engineers to use it as a basis and make their own comparisons.

[ozeco41]

Ozeco post #128: "Then Bazant ad various colleagues wanted to develop a general model for building progressive collapse. They developed the model using concepts of "crush up/crush down" and supported those concepts using a lot of complicated looking mathematics and confusing language. Typical academics. However they never explicitly (as far as I can see) moved away from the original assumption of axial contact between columns."

That is correct. In BV they derive crush up and crush down equations of motion based on successive upward and/or downward axial impacts. The concept of "crush down before significant crush up" was introduced in that paper. Almost nobody seemed to notice# that the justification for no significant early crush up is that there is insufficient upwards force to buckle columns in the up direction.... # I noticed that comment when the paper was first published. Disagreed with it then for a couple of reasons and decided that I did not agree BUT could not be bothered to follow the argument through to see if I could justify a different assumption and thereby rebut Bazant. No way would I be up to decrying a highly regarded academic unless the grounds were clear and clearly winnable. So totally different to my approach to (say for example) Tony Szamboti's work and David Chandler's. Both of them make easy to see false assumptions as premises for their analyses and are therefore (relatively) easy to rebut.
...The concept of crush down, then crush up is just a math trick,......amd I have long suspected that the conclusions they draw are artefacts of the base assumptions but I do not have the energy or interest to prove that so have never previously commented on it. I simply do not rely on Bazant for my own explanations as explained in previous posts.
...It is not a property of real buildings and observation of verinage style demos have yet to produce one actual example to my knowledge......I have no basis for comment either way.
...Then the strangest thing happened: People began to imagine that crush down then crush up was a real physical property of buildings. The quotes I provided by R Mackey and Dave Rogers show that even people with experience in physics could easily mistakenly believe that crush down before crush up, surviving upper blocks and magic zone Bs must exist for real buildings because Bazant proves it in BV and removes all doubt in BL.......In my career as a practising engineer then as a manager of engineers I have on several occasions seen belief in authority figures taken too far by disciples who were using the work of the authority. Two of those involved structures related to the main water supply pipeline serving Sydney. Neither world shattering but on both occasions I got no thanks for identifying fundamentally wrong reasoning. One case mattered. The other didn't.

The underlying problem IMNSHO is that people so often get too close to the detail and lose the big picture or context and/or base assumption. A lot of the "discussion" (confrontation) truthers v debunkers on WTC matters is about detail out of any rational context.

Without going to too much derailing detail the big picture for WTC 7 makes any suggestion of demolition ridiculous. It is an ancillary event to aircraft strikes on each of the twin towers. The idea that anyone could pre-plan to demolish WTC 7 under the cover of a couple of aircraft strikes it ludicrous. The idea that anyone could expediently arrange demolition at the last moment seeing how good a scene the Twin Towers were setting is beyond any sense of possibility. So there is no point arguing about free fall. And no point bothering to counter the "truthers" ploy of making the stupid claim that FFA == demolition. The whole idea of demolition is beyond any possibility. But the reason I state that is as an example of "losing the plot" --- "forgetting the context" -- losing sight of the premise assumptions OR "not seeing the forest for the trees" :D:) End of adrenaline rush. :o

...You are the first person I have seen in this forum that recognizes this. Blush :o

[ozeco41]

That question is interesting in view of the recent attacks to his work, though, as they are based on a wrong understanding of how models work. Also for people to understand that it's not necessary for the real world to behave exactly like the model in order for the model to be applicable to the real world. And also for people to understand that in spite of that, there are limits to that applicability itself.

When the limits of the model are not well known or understood, a comparison with the real world is helpful to see how good an approximation the model is. If the model gives a decent approximation of a certain parameter when compared to the real world, there is a basis to think that it can give approximate predictions in other real world cases. It may seem random,......understood. but in some cases having that approximation is better than having nothing at all. Certainly..
...In the real WTC case, the comparison of the model with the real world shows little difference in expected (by the model) vs. real collapse time, for example. That hints towards the utility of Bazant's model to estimate collapse times to a certain accuracy......BUT (Make that a big BUT ) Always keep in mind that wrong methods which on one or two occasions give correct answers for wrong reasoning are a trap waiting for the unwary...All too often the wrong method can give right answers for the wrong reasons..(And don't ask me for a foolproof way to check -- just never forget your framing assumptions. Never let use of those assumptions become so routine that you forget how vulnerable they are. End of sermon from old fart. ;) ) ... Two specific and very similar cases are not enough to be convinced, but the material is now on the table for other engineers to use it as a basis and make their own comparisons....yes but see previous sermon :):)

[pgimeno]

..BUT (Make that a big BUT ) Always keep in mind that wrong methods which on one or two occasions give correct answers for wrong reasoning are a trap waiting for the unwary...All too often the wrong method can give right answers for the wrong reasons..(And don't ask me for a foolproof way to check -- just never forget your framing assumptions. Never let use of those assumptions become so routine that you forget how vulnerable they are. End of sermon from old fart. ;) )

Fully agreed. It's easy to lose the big picture and assume omnipotent properties on the details.

[ozeco41]

Fully agreed. It's easy to lose the big picture and assume omnipotent properties on the details.

http://conleys.com.au/smilies/thumbup.gif

[Major_Tom]

Here is an example of Newton's Bit conjuring up a surviving upper block and the magic zone B in his description of how real buildings would collapse.

From page 2 of the OOS model thread

I asked him:

"1) In BL, can you explain why Dr Bazant insists that crush down must be complete before crush up occurs. Does he mean this literally?

2) Do you consider the equations of motion in BV, equations 12 and 17, to be accurate considering the information in the ROOSD study?"

He answered: " ffs Read the paper. Here, let me explain it to you:

The upper block is accelerating at near g. This means that there is very little force being applied to it. We can imply that the absolute maximum height of destruction occurring through the upper block will happen at a rate equal to (g - a). However the upper block has some residual strength. This force is much less than the original capacity upper block which is somewhere in the neighborhood of 3*m*g.

There will be, during the initial stages of the collapse that forms the rubble layer, destruction on both the upper block and lower block. But once it gets moving? Not so much.

You've provided no information on how this is incorrect."

Original post http://forums.randi.org/showpost.php?p=5938765&postcount=77


I have given direct quotes from R Mackey, Dave Rogers and Newtons Bit applying the concept of crush down, then crush up, the surviving upper block and the magic zone B introduced in the BV progressive collapse model to descriptions of how they believe real buildings behave. 3 examples from 3 different posters who have experience problem-solving using the tools of physics.

They all have a good level of education but they all made the same mistake. Just a coincidence? Where did all three posters get the idea that crush down, then crush up and upper block survival can be applied to real buildings?

(Hint: Originally from Bazant's progressive mechanics derived in BV, proven "beyond doubt" in BL and applied to the WTC towers in BLGB)

[Major_Tom]

Here is a good example of how easy it is to mix the 2002 BZ argument and the 2007 BV crush down and crush up equations of motion if you are not careful:

Myriad wrote: "Bazant's model is a limiting case representing the most favorable assumptions for collapse arrest. Among those assumptions is that all the weight of the falling mass -- even the already crushed and broken rubble -- somehow lands squarely on columns.

In that model, meaning under those assumptions, crush-down precedes crush-up. Bazant shows how and why.

The extent to which crush-down did not precede crush-up in the actual collapse indicates only that those favorable assumptions for collapse arrest were not true, so collapse arrest was even more impossible."

original post http://forums.randi.org/showpost.php?p=5940324&postcount=86

Here Myriad freely mixes the BZ argument (2002) and it's simple one collision model with the crush up, crush down progressive collapse model presented in BV (2007).

A main purpose of BV (2007) was to derive the crush down equation (eq 12) and the crush up equation of motion (eq 17) for the crush front and roofline to accurately predict the movement of real buildings. The phrase "limiting case representing the most favorable assumptions for collapse arrest" has no meaning in the 2007 paper because BV equations 12 and 17 are derived to predict real motion of real buildings, not some theoretical extreme limiting case only.

Bazant talks about assumptions most favorable for survival in the one collision model in BZ (2002). It is a mistake to assume the same assumptions are applied to the crush up crush down model in BV published 5 years later with a very different purpose stated clearly in the introduction.

You cannot just mix all 4 Bazant papers together like you are making mashed potatoes. BZ gives one argument while BV, BL and BLGB develop equations of motion to describe real movement of real buildings, and we can see the equations applied to the WTC towers in BLGB.

You cannot quote about the assumptions most favorable for survival from the 2002 paper to refute my arguments against collapse progression model from a different paper describing a different model from a 2007 paper.

In the quote can you see how he mixes the two models without realizing it?

[ozeco41]

Here is an example of Newton's Bit conjuring up a surviving upper block and the magic zone B in his description of how real buildings would collapse..... Well I have no desire to get into the middle of a sandwich which is a heated personal conflict and clearly polarised "debunker side v presumed truther". Not the least for the reasons I have previously outlined about my reservations as to how far Bazant can be taken, including how Bazant's bits of ongoing thinking in various papers fit together if they do.

However.... :):D

In addition, sticking firmly to my policy of "think before applying models blindly", I need to progress my own thinking about the details of WTC Twin Towers collapses. And I will continue to limit myself to WTC Twin Towers. I will also continue my practice of working from what actually happened back towards the Bazant models i.e. the reverse of what seems to be the common practice of assume a model and see if it fits (or presume that it does???).

So I will post some more ideas about WTC but at this stage make preliminary comments on your two posts.

From post #139
...From page 2 of the OOS model thread I asked him:

"1) In BL, can you explain why Dr Bazant insists that crush down must be complete before crush up occurs. Does he mean this literally?

2) Do you consider the equations of motion in BV, equations 12 and 17, to be accurate considering the information in the ROOSD study?"

He answered: " ffs Read the paper. Here, let me explain it to you:

The upper block is accelerating at near g. This means that there is very little force being applied to it. We can imply that the absolute maximum height of destruction occurring through the upper block will happen at a rate equal to (g - a). However the upper block has some residual strength. This force is much less than the original capacity upper block which is somewhere in the neighborhood of 3*m*g.

There will be, during the initial stages of the collapse that forms the rubble layer, destruction on both the upper block and lower block. But once it gets moving? Not so much.

You've provided no information on how this is incorrect." Well that does not answer your questions AND throws the burden of proof back to you. It seems clear that you are receiving the short shrift that is afforded to those categorised as truthers. I will not address the merits of either the topic OR the apparent categorisation of yourself.

Then this seems to be the core issue of your following paragraphs:...They all have a good level of education but they all made the same mistake. Just a coincidence? Where did all three posters get the idea that crush down, then crush up and upper block survival can be applied to real buildings?...

Then from your second post - Post # - the central issue seems to be this:
...You cannot just mix all 4 Bazant papers together like you are making mashed potatoes. BZ gives one argument while BV, BL and BLGB develop equations of motion to describe real movement of real buildings, and we can see the equations applied to the WTC towers in BLGB.

You cannot quote about the assumptions most favorable for survival from the 2002 paper to refute my arguments against collapse progression model from a different paper describing a different model from a 2007 paper.

In the quote can you see how he mixes the two models without realizing it?
So I see those as the key points and I will give some thought into territory which I have not bothered with previously.

The central question from my perspective is "where in the global collapse of each of the twin towers did the top block fall apart"? Previously to this recent discussion I have accepted that the top block started off as an integral whole, fell apart somewhere in the global collapse and was not an integral hole at the bottom. It mattered not to me where it happened because integral whole or component parts it was the total falling mass which caused the pancaking OOS collapse.

I have never regarded Bazant's "crush up only happened at the bottom" as a viable explanation so leave it with me for a few hours.

[pgimeno]

You cannot quote about the assumptions most favorable for survival from the 2002 paper to refute my arguments against collapse progression model from a different paper describing a different model from a 2007 paper.

What arguments? You have shown no arguments against Bazant's collapse progression model, other that it does not correspond exactly with reality, something that Bazant knew as I have proved in the OP, and which is irrelevant to his arguments.

[Tony Szamboti]

Bazant got 31 times overload. Just for interest when I first answered the question back in early 2008 I guestimated it was in the order of 20 times to 50 times overload. Without the complicated maths.


Now recall my suggestion to "remember point A". The "jolt" which Bazant's conservative model predicted as the top block struck at "point A"? That is the "Missing Jolt" which Tony Szamboti went looking for in his paper of that name. He took Bazant's worst case as gospel. But the WTC Twin Towers did not start to collapse by the worst case of Bazant's model. Hence the futility of Tony's search for a jolt which wasn't needed. It wasn't there because it wasn't needed.

The overloads you guesstimated could not happen without a jolt and your use of it here shows you want it both ways. You want an overload without a jolt. Sorry, but you can't have that in this world.

If you decide to back off the need for a jolt as you contradictorily state in the second paragraph I am quoting from you, then you need to explain why every Verinage demolition shows a significant and measurable deceleration (jolt). If WTC 1 were somehow able to naturally collapse without a jolt it would be a severe exception to the rule.

[femr2]

you need to explain why every Verinage demolition shows a significant and measurable deceleration (jolt).
I don't think this is the right thread for jolt discussion, and if you respond Tony, please make it a once only with a redirect to one of your other jolt threads.


Verinage demolitions show *jolts* because we can *see* the behaviour. There is no perimeter.

As far as I'm concerned, there ARE jolts during the WTC descents, but they are between elements which are either disconnected from the core and perimeter (floors), or (as they are nothing like axial core column impacts) of much less magnitude and not transmitted to regions such as the NW corner due to a) non-rigid structure and b) short *jolt* duration and c) lots-n-lots of jolts spread out over time and...

If WTC 1 were somehow able to naturally collapse without a jolt it would be a severe exception to the rule.
Regardless of natural or not, WTC 1 mode of descent is quite different to verinage. I don't think they should be compared. Verinage is applied to very different structures.

[femr2]

Well I have no desire to get into the middle of a sandwich which is a heated personal conflict and clearly polarised "debunker side v presumed truther".
A wise decision.

In my opinion, that this thread exists allows an underlining of previous mistakes.

It has been made clear that there are quite strict limitations on applicability of Bazant's model.

Poring over prior incorrect usage is unlikely to result in all of those responsible for crossing the line turning around and making amends.

I suggest that from this point on (6/9/10) there is no excuse, and I expect that any instances of folk applying the model incorrectly will end up being posted here and dissected. That's a good thing, and a useful end result, imo.

[beachnut]

A wise decision.

In my opinion, that this thread exists allows an underlining of previous mistakes.

It has been made clear that there are quite strict limitations on applicability of Bazant's model.

Poring over prior incorrect usage is unlikely to result in all of those responsible for crossing the line turning around and making amends.

I suggest that from this point on (6/9/10) there is no excuse, and I expect that any instances of folk applying the model incorrectly will end up being posted here and dissected. That's a good thing, and a useful end result, imo.
911 truth has no clue what models are for, they have failed CD delusion as they waste time commenting on work they can't comprehend, let alone use to cure their failed delusions.

[pgimeno]

It has been made clear that there are quite strict limitations on applicability of Bazant's model.

I don't agree on that. There are limitations, but these limitations are not well known. Therefore, it can't be claimed that there are quite strict limitations. There are limitations, but we don't know the limitations of the limitations, so to say.

(Does that count as a second order derivative? Will it be infinitely derivable? Do we get a squared error in the measurement? :D)

I was serious on the first paragraph, though. "Quite strict limitations" is a bit of a stretch. In case of doubt, a comparison with the real world can be helpful in determining the applicability.

[femr2]

I don't agree on that. There are limitations, but these limitations are not well known. Therefore, it can't be claimed that there are quite strict limitations. There are limitations, but we don't know the limitations of the limitations, so to say.
What I'm saying is that if someone appears to be misapplying the model, it's likely going to be brought in here and given a shake-down.

Hopefully no-one will from now on :cool:

[ozeco41]

The overloads you guesstimated could not happen without a jolt and your use of it here shows you want it both ways. You want an overload without a jolt. Sorry, but you can't have that in this world.... Tony this is not the thread to reopen "jolt" debate.

I am writing in the context of what Major_Tom labels OOS collapse during the global collapse phase of the twin tower destruction. Your "jolt" hypothesis relies on one of two possible situations which could apply to the "initial collapse". Those two being: Initial collapse occurred due to impact and accumulated fire damage alone; OR it resulted from that damage assisted by demolition. Your jolt paper does not rebut the first, no demolition, option which is the setting I am writing about.

Explaining briefly - within the no demolition scenario - once the initial collapse was under way there was no significant column on column axial contact to transfer loads. There could not be because the top block was falling. So, whatever the detailed mechanisms involved, top column bits were already bypassing their bottom column counterparts.

The only significant contact in the outer floor and outer tube area was top block on floor area. That is why it was 20-50 times overload and sheared the floor connectors with minimal jolt.

So your scenario is only one of two potential scenarios. I am addressing the other scenario which you ignore and this is not the thread to reopen Jolt discussion. Full explanation is beyond the scope of this thread and I won't pursue it here.

... you need to explain why every Verinage demolition shows a significant and measurable deceleration (jolt). If WTC 1 were somehow able to naturally collapse without a jolt it would be a severe exception to the rule. Sorry but I never accept reversal of burden of proof. Even if I did there is no analogy between verinage and the "no demolition" mechanism which occurred at WTC.

[ozeco41]

A wise decision. Could be age ;) ----- the 41 in the user name is easy to decode.

In my opinion, that this thread exists allows an underlining of previous mistakes... ...and maintaining the narrow scope of topic could assist reasoned discussion. The "noise to signal" ratio tends to get a bit high when questioning the accepted wisdom.

It has been made clear that there are quite strict limitations on applicability of Bazant's model.... ...but: We are not clear where the lines are at this stage; AND Some members are content with "its only a model and models have limits" whilst others like me currently want to know "where those limits are"; AND Some members like me up till three days ago just avoid going near any possible limits.

...Poring over prior incorrect usage is unlikely to result in all of those responsible for crossing the line turning around and making amends... Are you sure you meant "all" :) Surely you jest - maybe "any" or "few" ;)

I suggest that from this point on (6/9/10) there is no excuse, and I expect that any instances of folk applying the model incorrectly will end up being posted here and dissected. That's a good thing, and a useful end result, imo....and working with real examples is usually the most productive way of defining where the lines are in the grey areas.

[ozeco41]

I don't agree on that. There are limitations, but these limitations are not well known. Therefore, it can't be claimed that there are quite strict limitations. There are limitations, but we don't know the limitations of the limitations, so to say.

(Does that count as a second order derivative? Will it be infinitely derivable? Do we get a squared error in the measurement? :D)

I was serious on the first paragraph, though. "Quite strict limitations" is a bit of a stretch. In case of doubt, a comparison with the real world can be helpful in determining the applicability.
My thoughts also.

See my response to femr2.

The implicit limits are quite strict BUT they have not been made explicit and "we" are currently unsure where they are.

Plus some of us ( at least me :D ) are mainly interested in WTC 9/11 application not development of generic models.

[Major_Tom]

A good example of utter cluelessness:

Seymour Butz to me, page 14 of the OOS model thread, post #522:

"Seriously now, it's been pointed out that you're misrepresenting Bazant's papers.

The crush up/down thing STILL refers to the idealized case of the strength of the columns, not the floors, being the determining factor in his equations.

There's more examples of your twoofiness available to any who care to waste their time pointing them out to you.

If you can't admit that, there's zero reason to engage you seriously. Instead, it is appropriate to ridicule you if you cannot.

This is what you deserve."

Link to post http://forums.randi.org/showpost.php?p=6033382&postcount=522

Notice that most every example of the misapplication of crush down, then crush up to real towers and freely mixing the BZ (2002) paper and the BV (2007) paper with no regard to the differing purpose of each paper given in this thread contain insults to me over my "stupidity" and "troofiness', while the posters remained ignorant of their own false statements.

This is why many people associate this forum with propaganda, not honest debate.

[beachnut]

A good example of utter cluelessness:

...

This is why many people associate this forum with propaganda, not honest debate.
You think you can debate CD; it is a delusion. You must debate the delusions you have on 911 at a forum where delusions are accepted, not a skeptics forum. You think your delusion is real, this is why you call rational thinking and evidence propaganda. After 8 years, you have failed, you are not good at figuring out 911.

You have to debate your CD delusion at other forums, skeptics require proof and evidence; things you never provide.

You have shown you can't handle real engineering models by attacking Bazant's model. Publish your nonsense and delusions, and find confirmation of your CD theory.

[ozeco41]

...Notice that most every example of the misapplication of crush down, then crush up to real towers and freely mixing the BZ (2002) paper and the BV (2007) paper with no regard to the differing purpose of each paper given in this thread contain insults to me over my "stupidity" and "troofiness', while the posters remained ignorant of their own false statements.... The strong polarisation is disappointing but nothing you say is likely to change it. Since you are painted into the truther camp your attempts to discuss legitimate issues are being swamped by the high "noise to signal" reactions to your perceived truther position.

...This is why many people associate this forum with propaganda, not honest debate. Whether the generalisation is true or not I don't think that making the statement will gain you any friends.

[pgimeno]

A good example of utter cluelessness:

Seymour Butz to me, page 14 of the OOS model thread, post #522:

"Seriously now, it's been pointed out that you're misrepresenting Bazant's papers.

The crush up/down thing STILL refers to the idealized case of the strength of the columns, not the floors, being the determining factor in his equations.

There's more examples of your twoofiness available to any who care to waste their time pointing them out to you.

If you can't admit that, there's zero reason to engage you seriously. Instead, it is appropriate to ridicule you if you cannot.

This is what you deserve."

Link to post http://forums.randi.org/showpost.php?p=6033382&postcount=522

Notice that most every example of the misapplication of crush down, then crush up to real towers and freely mixing the BZ (2002) paper and the BV (2007) paper with no regard to the differing purpose of each paper given in this thread contain insults to me over my "stupidity" and "troofiness', while the posters remained ignorant of their own false statements.

I've been trying to match Seymour Butz's comment with your interpretation, to no avail. I've even checked the context in which that was said, to see if there's a reference to [BZ] which I missed.

I'm failing to see how Butz's comment makes any reference to [BZ] whatsoever. Please explain (or accept his conclusion on the ridicule you deserve).

[Myriad]

Apparently it's somehow improper to refer to information originating from more than one paper when writing a post.

Who knew? It must be something like the injunction in Leviticus about mixing linen and wool in the same garment.

Respectfully,
Myriad

[ergo]

Every decent 9/11 researcher from both sides of the fence can agree that the original initiation of each collapse and the events leading to it are perhaps the only time period in which an intentional demolition and a natural collapse are distinguishable.

Like who, for example?

Controlled demolition and natural collapses (which, for one thing are always partial, except for perhaps earthquake-hit structures) look very different. Not only that, but the Twin Towers' disintegration resembles neither natural collapse nor typical CD.

It is foolish to miss this point and associate a careful study of the collapse initiation sequences of each building with claims of space beams, freefall for all 3 towers and no planes.

Well, now you're the one creating strawmen.

[Major_Tom]

Pgimeno and Myriad, you still cannot see the difference between the ideal case of a single impact with assumptions most optimaol for survival of the building in BZ (2002) and the derivation of equations of motion to be used to predict the motion of real buildings in BV (2007)?

If you mix the 2 arguments, then you must be totally lost when reading BV, BL and BLGB.

Besides Ozeco, is there anyone in this forum that can spot the mistake Myriad keeps making?

The modified BV equations of motion applied to WTC1 and 2 in BLGB:

http://www.sharpprintinginc.com/911/images/photoalbum/13/BLGB_fig_7.jpg

Myriad and Pgimeno, why do you think Bazant is showing how WTC1 and 2 data points match his crush down equation of motion originally derived in BV?

If your reasoning is correct, then the data points should descend faster than what you believe are equations of motion for an idealized case with assumptions most optimal for survival.

Do you really believe the BV equations of motion are intended to represent motion of the slowest possible descent of a building under conditions most optimal for survival?

Is he trying to match motion of real buildings of just derive a theoretical upper limit of the slowest possible descent?

No need to guess. Just read the introduction and conclusions of BV.

No need to guess, just watch how he applies the equations to WTC1 in BLGB.

[beachnut]

Pgimeno and Myriad, you still cannot see the difference between the ideal case of a single impact with assumptions most optimaol for survival of the building in BZ (2002) and the derivation of equations of motion to be used to predict the motion of real buildings in BV (2007)?
....
The cool thing about you guys with the CD delusion, when you publish your ideas in a real journal, they get comments like nonsense and delusional. Publish your junk and prove me wrong. Take some action.

BTW, Bazant's model is applicabliby to the real world. Bazant's model can be used to identify people who don't understand the real world and engineering models. Publish your claims in a real journal. Is your CD delusion based on thermite or explosives? Your model is not applicable to the real world because you have no evidence for your CD claims. 2 days and it will be 9 years, and Bazant's model was done in two days. How many more days before you publish your model? Heiwa got his letter published, why can't you do something more than attack Bazant? Any plans on going to engineering school? Which school will you pick? Good luck publishing your fancy fake engineering ramblings.

Why not shoot your post off to the journal like Heiwa did with his letter?

[pgimeno]

Pgimeno and Myriad, you still cannot see the difference between the ideal case of a single impact with assumptions most optimaol for survival of the building in BZ (2002) and the derivation of equations of motion to be used to predict the motion of real buildings in BV (2007)?

I don't see the relation between that and Seymour Butz's statement that the crush-up/crush-down was related to the strength of the columns, not the floors, being the determining factor. This is the relevant part of the quote into play:

The crush up/down thing STILL refers to the idealized case of the strength of the columns, not the floors, being the determining factor in his equations.

And that is indeed the case in [BV]. How is that related to [BZ]?

The whole quote is here, for you to see that in its context:

Seriously now, it's been pointed out that you're misrepresenting Bazant's papers.

The crush up/down thing STILL refers to the idealized case of the strength of the columns, not the floors, being the determining factor in his equations.

There's more examples of your twoofiness available to any who care to waste their time pointing them out to you.

If you can't admit that, there's zero reason to engage you seriously. Instead, it is appropriate to ridicule you if you cannot.

This is what you deserve.

[Major_Tom]

Seymour again: "The crush up/down thing STILL refers to the idealized case of the strength of the columns, not the floors, being the determining factor in his equations. "

It does. That is one of Bazant's mistakes. This is how the concept of crush down, then crush up was born.

When you believe that real buildings exhibit the behavior of crush down, then crush up, you make the same mistake.

Now please read the quotes I gave from Dave Rogers, R Mackey and Newtons Bit again.

They make this mistake. In BLGB Bazant makes the same mistake. They apply crush down, then crush up to real buildings and believe that some upper block survives until colliding with the earth.

This is not the sentence in the Seymour quote I have a problem with.

[Myriad]

Myriad and Pgimeno, why do you think Bazant is showing how WTC1 and 2 data points match his crush down equation of motion originally derived in BV?


I think he did it to show that the original model makes adequate predictions.

Why does the model make adequate predictions? It could be because the assumptions made in the original model are actually accurate (that is, rubble did only impact on columns and every column experienced 3-hinge buckling), or it could be that the phenomenon being modeled is not very sensitive to the accuracy of those assumptions. Either way makes it an adequate model.

However, since it is obvious that three-hinge buckling of every column did not occur, the point I gather is the latter one: that the predicted collapse time is not very sensitive to the accuracy of the assumptions made about the exact mode of structural component failure (e.g. column buckling vs. column fracture vs. shearing of floor connections).

If your reasoning is correct, then the data points should descend faster than what you believe are equations of motion for an idealized case with assumptions most optimal for survival.


If my reasoning is correct that the collapse time is not sensitive to the assumptions made about the exact mode of structural component failure, then the collapse time should be sensitive to the assumptions made about the exact mode of structural component failure? I think not.

One could make an argument based on energy balance that the actual data should be faster, but to show it should be measurably faster given the errors of measurement and the range of uncertainty in the model input parameters (such as the actual masses of floors) would require a quantitative argument that I have not seen anyone make.

Do you really believe the BV equations of motion are intended to represent motion of the slowest possible descent of a building under conditions most optimal for survival?

Is he trying to match motion of real buildings of just derive a theoretical upper limit of the slowest possible descent?


First he derived a theoretical upper limit of the slowest possible descent, and then he pointed out that the predicted descent is not significantly slower than the actual measured collapse. This suggests that the collapse time is not sensitive to the assumptions made about the mode of structural component failure.

If I recall correctly, models have also been created assuming the fastest possible descent, in which the inertia of the floors in the lower structure is the only resistance mechanism (that is, the columns below each floor are assumed to break with zero energy absorption the moment the rubble mass from above touches that floor), and those models also make predictions of collapse times close to what was observed. Which is consistent with the above.

In summary: one paper shows the tower collapses even under best-case assumptions for collapse arrest; the other shows that the best-case assumptions don't make the model grossly inaccurate with respect to predicted collapse time. Two different conclusions that are entirely consistent with one another.

You appear to believe that if the model makes best-case assumptions then that must make it grossly inaccurate with respect to the collapse times it predicts. That doesn't follow. Without a quantitative argument to that effect, any such belief on your part holds no significance.

Respectfully,
Myriad

[Major_Tom]

Myriad, last post:

"First he derived a theoretical upper limit of the slowest possible descent, and then he pointed out that the predicted descent is not significantly slower than the actual measured collapse."

Show me where he says so. BV never claims that his crush up, crush down model does this.

More mind reading of Bazant. Show me the quotes.

Show me where he says the concept of crush down, then crush up only applies to a case most favorable to survival.

This also means you disagree with the quotes I gave of R Mackey, Dave Rogers and Newtons Bit. THey apply the concept quite literally to real buildings.

[Myriad]

They apply the concept quite literally to real buildings.


I think applying a model of building collapses to building collapses makes a certain amount of sense, actually. What else would you apply it to?

But, if you have a problem with it... I don't know, complain to somebody, or something.

Respectfully,
Myriad

[Major_Tom]

Myriad post 162:

"First he derived a theoretical upper limit of the slowest possible descent, and then he pointed out that the predicted descent is not significantly slower than the actual measured collapse."

Myriad, you just made this up. Show us the section where he does this.

[Major_Tom]

Balzac

http://img340.imageshack.us/img340/8398/vitry.gif

Just imagine if there were another 15 floors placed under the lower portion. Why on earth would anyone expect the upper block to survive while riding on a rubble zone like it is on a magic carpet?

Where did anyone get the idea that upper blocks can ride the rubble with minimal crush up?


So can the concept of crush down before crush up be applied to real buildings?

Are the BV equations of motion (BV eq 12 and 17) real or just a math trick?

[bill smith]

this is very refreshing Tom. It seems to me that Bazant and the various Bazant cameos may have been delberately contrived to confuse the issue. How soon after 9/11 did Bazant's first paper appear ?

[ozeco41]

...

http://img340.imageshack.us/img340/8398/vitry.gif

Just imagine if there were another 15 floors placed under the lower portion. Why on earth would anyone expect the upper block to survive while riding on a rubble zone like it is on a magic carpet?...
A great graphic to make the point
http://conleys.com.au/smilies/thumbup.gif

[Tony Szamboti]

A great graphic to make the point
http://conleys.com.au/smilies/thumbup.gif

It seems you are forgetting that the big difference between the Verinage demolitions and the fall of WTC 1 is that they all have a significant deceleration and lose velocity measurably when the upper section hits the lower.

[ozeco41]

It seems you are forgetting that the big difference between the Verinage demolitions and the fall of WTC 1 is that they all have a significant deceleration and lose velocity measurably when the upper section hits the lower.
Not so Tony for two reasons.
1) I was commenting on the clip as an example of what has been discussed in this thread without specific reference to WTC. WTC is its own specific subset of "buildings" and arguable at the weakest end of building types because of the vulnerability of the tube in tube design to run away pancaking once initial collapse occurred.
2) The impact of "top block" on "lower tower" for both WTC towers happens after the top block is descending. The only significant resistance offered by the lower towers at that stage comes from:
a) the shearing of the next lower floor - whether taken as one floor or a composite of several; AND
b) the resistance of the core which at that stage is mostly beam on beam contacts and an order of magnitude less than what the columns would have resisted if properly abutted axial contact had been available.

[BigAl]

Balzac

http://img340.imageshack.us/img340/8398/vitry.gif

Just imagine if there were another 15 floors placed under the lower portion. Why on earth would anyone expect the upper block to survive while riding on a rubble zone like it is on a magic carpet?


It's not obvious to me that given more lower floors, the collapse would come to a halt before reaching the ground.

The mass of the falling part gets larger and accelerates with each destroyed floor. If the collapse doesn't halt with 5 floors why should it halt at 20 floors?

The mass of the falling part doesn't have to be a rigid body to be effective as mass.

[Tony Szamboti]

The mass of the falling part doesn't have to be a rigid body to be effective as mass.

It does for it to deliver an amplified load.

[BigAl]

It does for it to deliver an amplified load.

More momentum is more momentum. If there is sufficient momentum to initiate the collapse, the momentum only grows as the collapse proceeds.

[Tony Szamboti]

More momentum is more momentum. If there is sufficient momentum to initiate the collapse, the momentum only grows as the collapse proceeds.

Loose rubble does not deliver the same type of load as an intact structure.

[excaza]

For all you "loose rubble" lovers

http://en.wikipedia.org/wiki/Center_of_mass

[leftysergeant]

Loose rubble does not deliver the same type of load as an intact structure.So? That does not mean that it will not deliver AS MUCH of a load.

A ton of feathers, a ton of bircks.

It makes a difference only when dropped from more than a hundred feet.

The fact that the debris was loose and, to some degree fluid, actually made it more useful for the work at hand because it would not so easilly become entangled in anything.

There is also the extra force that the rubble was able to apply to shove the perimeter columns out of the vertical, A flowing fluid applying force evenly over a surface as large as a panel of perimeter columns is certainly going to speed up the collapse.

You really need to think these things out a little further.

[BigAl]

Loose rubble does not deliver the same type of load as an intact structure.

Even to the degree this is true, so what? Momentum increases with each floor.

[Myriad]

Myriad post 162:

"First he derived a theoretical upper limit of the slowest possible descent, and then he pointed out that the predicted descent is not significantly slower than the actual measured collapse."

Myriad, you just made this up. Show us the section where he does this.


The figure showing calculated descent rate versus observed in BLGB, which is conveniently posted in post 158.

The "slowest possible descent" is not directly claimed, but it follows from consideration of kinetic energy that a descent time calculated based on parameters reflecting the best case for collapse arrest (maximum energy absorption by the structural members, that is, 3-hinge buckling of every single column, one of the model's basic assumptions that does not change over the sequence of papers) must also be the slowest. (One must also read "possible" as constrained by known characteristics of the specific collapses in question; for instance, slower collapse would be possible if earth's gravity were different, or if there were more floors spaced closer together, or if the columns were reinforced concrete adding a significant additional energy sink.)

Really, guys, insisting that any statement in discussion regarding the papers is invalid unless it's an exact quote or close paraphrase of the papers themselves is rather silly. If you just want someone to repeat the papers to you, there are special-needs services available that will do that.

Respectfully,
Myriad

[Major_Tom]

DIrect quotes of Bazant are useful so we can separate what he writes from what you imagine he writes.

That is why you can find no example from BV to support your claim that he is deriving equations 12 and 17 for a theoretical best case scenario.

[Miragememories]

Even to the degree this is true, so what? Momentum increases with each floor.
Unless there is a decrease in mass.

MM

[Disbelief]

Unless there is a decrease in mass.

MM

How exactly would this happen?

[Miragememories]

How exactly would this happen?
Chaos theory.

MM

[BigAl]

Unless there is a decrease in mass.

MM

Where did it go?

In the meantime, with each floor V is increasing and as a result momentum is increasing.

[femr2]

Where did it go?

In the meantime, with each floor V is increasing and as a result momentum is increasing.

No. *crush front* traversal rate was linear 4/5 seconds after initiation. ~27m/s.

[ozeco41]

Loose rubble does not deliver the same type of load as an intact structure.
A disarming truism Tony. ;)

As it relates to dynamic impacts - not static - "loose rubble" could be "better", it could be "worse" than an intact structure. It depends on the manner of contact when the impact load is applied.

And, in the case of WTC1 and WTC2, that goes to the whole complex area of analysis where Gage's boxes and Heiwa's blocks represent one extreme of the possibilities.

...my "cut wire baskets" are towards the other end of that range and being just one attempt at analogy for what really happened.

...and I don't think anyone could detail analyse the actualities of WTC1 and 2 on 9/11 - the "which beam hit which beam" and "which column did what" level of detail will never be available. And the task is probably too complex even if that detail was available. (But then I come from the slide rule generation... :rolleyes: )

Which is why modelling approximations such as Bazant's are valuable.

...provided they are not taken outside the range of validity set by the assumptions.

[ozeco41]

No. *crush front* traversal rate was linear 4/5 seconds after initiation. ~27m/s.
Which implies an interesting "balance" between:
1) the increasing total falling mass; AND
2) the more or less constant shear failure limited impact resistance of successive floors.

:rolleyes:

[pgimeno]

Seymour again: "The crush up/down thing STILL refers to the idealized case of the strength of the columns, not the floors, being the determining factor in his equations. "

It does. That is one of Bazant's mistakes. This is how the concept of crush down, then crush up was born.

One of Bazant's mistakes, you say? Why is it a mistake to build a model based on that? You can claim to have a mathematical model based on better assumptions, if you do (do you, perchance?) but to say that it's a mistake without any reason is merely baseless smearing.

Now please read the quotes I gave from Dave Rogers, R Mackey and Newtons Bit again.

I've read them again, and in my opinion, only Dave Rogers is making the mistake you attribute to all three.

Mackey's quote is an explanation in reply to this question:

This has come into my mind when thinking about this before and I have no idea if it's right so can someone explain why it's wrong.

The forces acting on the upper and lower blocks are equal but opposite, the force acting on the lower block does not accelerate the lower block downwards but the force on the upper block does accelerate the upper block upwards so there is more destructive force acting on the lower block.

Obviously, alexi_drago's question (why it's wrong) is purely theoretical, as is Mackey's reply, as evidenced by his ending phrase: "Again, this is slightly idealized, but you get the point. Unless you're a Truther".

Newton's Bit, as ozeco41 already noted, merely explained Bazant's words to you, throwing the burden of proof to you again. Prior to your quote, he already wrote the following:

Bazant and Verdue sets out to model and understand progressive collapse. Not prove how the WTC collapsed. It uses the WTC only as a paradigm. I.e. an example, a model, a pattern, etc etc. It then applies the conclusions of this model to other buildings, as that is the stated purpose of this model.
Crystal clear to those who don't have a smearing agenda: he doesn't believe that Bazant's model should be taken literally as a description of how the collapse happened.

They make this mistake. In BLGB Bazant makes the same mistake. They apply crush down, then crush up to real buildings and believe that some upper block survives until colliding with the earth.

Your repeated claim that it's a mistake won't make it a mistake. It's valid engineering because predictions can be extracted out of it. These predictions turn out to be quite accurate, therefore supporting the applicability of the model to real buildings for the purpose of measuring the speed of fall.

What you seem to fail to see again and again, is that the model can be applied to the real world to obtain approximations for some purposes but not for all purposes and not for no purpose. In particular, it can't be applied to the measurement of the crush direction for the WTC, but it can be applied to the measurement of the speed of fall.

[pgimeno]

Even to the degree this is true, so what? Momentum increases with each floor.
Unless there is a decrease in mass.

MM
Wrong.

Unless the decrease in mass of the rubble layer equals or exceeds the gain of mass due to the ongoing crushing.

Which is quite ridiculous itself.

[Edited to add: Forgot to specify that that applies to an assumption of constant velocity.]

[bill smith]

A disarming truism Tony. ;)

As it relates to dynamic impacts - not static - "loose rubble" could be "better", it could be "worse" than an intact structure. It depends on the manner of contact when the impact load is applied.

And, in the case of WTC1 and WTC2, that goes to the whole complex area of analysis where Gage's boxes and Heiwa's blocks represent one extreme of the possibilities.

...my "cut wire baskets" are towards the other end of that range and being just one attempt at analogy for what really happened.

...and I don't think anyone could detail analyse the actualities of WTC1 and 2 on 9/11 - the "which beam hit which beam" and "which column did what" level of detail will never be available. And the task is probably too complex even if that detail was available. (But then I come from the slide rule generation... :rolleyes: )

Which is why modelling approximations such as Bazant's are valuable.

...provided they are not taken outside the range of validity set by the assumptions.

How soon after 9/11 did Bazant's first model appear ?

[ozeco41]

How soon after 9/11 did Bazant's first model appear ?
From the footnotes to Bazant and Zhou:The original version with Eqs. 1 and 2 was originally submitted to ASCE on September 13, 2001, and an expanded version with Eq. 3 was submitted to ASCE on September 22, 2001. The appendices were added between September 28 and October 5, 2001; The preliminary report Bazant and Zhou 2001 on which this article is based was posted on September 14, 2001...
Didn't waste any time did they? :)

[ozeco41]

...What you seem to fail to see again and again, is that the model can be applied to the real world to obtain approximations for some purposes but not for all purposes and not for no purpose. In particular, it can't be applied to the measurement of the crush direction for the WTC, but it can be applied to the measurement of the speed of fall. Whilst I am in broad agreement with what you say I am nervous about one aspect.

We know that "... it can be applied to the measurement of the speed of fall [for WTC1 or 2]" because we can measure that speed of fall by other methods and those do in fact confirm the model.

My concern is that it may happen to be right for WTC for wrong reasons AND that, if applied to other buildings may give wrong answers.

Not that I can see any practical consequences arising but.....

[pgimeno]

My concern is that it may happen to be right for WTC for wrong reasons AND that, if applied to other buildings may give wrong answers.

I know, but I think I've already seen, maybe in this thread, a justification for the little sensitivity of the model to the assumptions with regards to the speed of fall. If so (sorry to be so vague, I'd have to find who said it and what it was exactly), then the application would be for right reasons.

[Tony Szamboti]

A disarming truism Tony. ;)

As it relates to dynamic impacts - not static - "loose rubble" could be "better", it could be "worse" than an intact structure. It depends on the manner of contact when the impact load is applied.

And, in the case of WTC1 and WTC2, that goes to the whole complex area of analysis where Gage's boxes and Heiwa's blocks represent one extreme of the possibilities.

...my "cut wire baskets" are towards the other end of that range and being just one attempt at analogy for what really happened.

...and I don't think anyone could detail analyse the actualities of WTC1 and 2 on 9/11 - the "which beam hit which beam" and "which column did what" level of detail will never be available. And the task is probably too complex even if that detail was available. (But then I come from the slide rule generation... :rolleyes: )

Which is why modelling approximations such as Bazant's are valuable.

...provided they are not taken outside the range of validity set by the assumptions.

Any legitimate statistical analysis would show that a random chaotic process would have produced a definitive deceleration if the structure below and above had been intact when they impacted after the initial fall. WTC 1 would be a severe exception to the rule if it were somehow able to collapse without this occurring.

[ozeco41]

Any legitimate statistical analysis would show that a random chaotic process would have produced a definitive deceleration if the structure below and above had been intact when they impacted after the initial fall. WTC 1 would be a severe exception to the rule if it were somehow able to collapse without this occurring.
Whether right or wrong the key issue is the size of the "definitive deceleration".

And as I said "It depends on the manner of contact when the impact load is applied."

..specifically the lack of column on column axial contact which means no easily measured jolt of large magnitude.

[Tony Szamboti]

Whether right or wrong the key issue is the size of the "definitive deceleration".

And as I said "It depends on the manner of contact when the impact load is applied."

..specifically the lack of column on column axial contact which means no easily measured jolt of large magnitude.

You are arguing for a severe exception or an extraordinary event without providing extraordinary evidence for it.

[twinstead]

You are arguing for a severe exception or an extraordinary event without providing extraordinary evidence for it.

Indeed. And we mustn't do that, must we Tony? :rolleyes:

[carlitos]

Am I reading this right? Does Tony think that there should have been "column on column axial impact" in the WTC tower collapses? That seems impossible, given the twisting and turning the upper sections showed. Is it only the idealized model by Bazant that gave people this idea?

[ozeco41]

You are arguing for a severe exception or an extraordinary event without providing extraordinary evidence for it.
Whether your statement is applicable or not it does not call for extraordinary thinking.
Recalling that the precursor condition for your lost jolt is that the top block is falling.

Therefore no column on column contact at that time.

(And, yes, I am aware of where the next step of logic goes.)
Indeed. And we mustn't do that, must we Tony? :rolleyes: ;)
Am I reading this right? Does Tony think that there should have been "column on column axial impact" in the WTC tower collapses? That seems impossible, given the twisting and turning the upper sections showed. Is it only the idealized model by Bazant that gave people this idea?Not only "should have been" - his hypothesis relies on it.

Tony's "Missing Jolt" paper is premised on "column on column axial impact" where columns are the only structural elements capable of developing sufficient resistance in one isolated sub-event which would be identifiable as a "jolt". Quoting from Graeme MacQueen & Tony Szamboti "The Missing Jolt: A Simple Refutation of the NIST-Bazant Collapse Hypothesis"
...any impulse at the impact zone between the 98th and 99th story floor slabs capable of causing collapse continuation would have had to cause the columns on at least the first stories on either side of the impact to deform elastically, and plastically, and then to buckle......so he takes the extreme case allowed by the assumptions in Bazant & Zhou and builds on it.
That extreme has column on column axial contact. It is valid for B & Z to use it as an approximation - it is on the "safe" side when it finds that there was sufficient energy to allow propagation of the global collapse. It is not valid for Tony to assume it. In fact, properly interpreted, the lack of a jolt is confirmation that there was not (significant if any) column on column axial contact.

And that goes right to the core of this topic "Applicability of Bazant's model to the real world" and previous discussion where I and others have agreed that Bazant and Zhou's model is valid within the limits of validity of the assumptions.

And, yes, there are steps of logic needed to complete the picture.
And, ironic though it may be, to that extent Tony's paper would seem to present part of "A Simple Refutation of the NIST-Bazant Collapse Hypothesis" :):D

[Miragememories]

Am I reading this right? Does Tony think that there should have been "column on column axial impact" in the WTC tower collapses? That seems impossible, given the twisting and turning the upper sections showed. Is it only the idealized model by Bazant that gave people this idea?
You make it sound like the upper sections had a life of their own.

MM

[ozeco41]

You make it sound like the upper sections had a life of their own.

MM
To the extent that the top block was falling it did have a life of its own.

And that much is common to both sides of the "argument":
1) It had sufficient life of its own to fall due to natural consequences of damage; OR
2) It had sufficient life of its own to fall because some naughty demolition had helped it.

Cheers. ;)

[bill smith]

From the footnotes to Bazant and Zhou:
Didn't waste any time did they? :)

This is not some vague thing- this is real. They produced and made public I presume the first draft two days after 9/11 . I call that foreknowledge in the most friendly of interpretations. Are you saying that it is reasonable to believe that they put together something like that in less than two days ?

The terms of their collaberation as two top professionals would have taken longer than that to work out. 9/11 was a surprise- remember ?

[Tony Szamboti]

In fact, properly interpreted, the lack of a jolt is confirmation that there was not (significant if any) column on column axial contact.

And, yes, there are steps of logic needed to complete the picture.
And, ironic though it may be, to that extent Tony's paper would seem to present part of "A Simple Refutation of the NIST-Bazant Collapse Hypothesis" :):D

Your first sentence here is a large leap in logic. The inertia of the upper section would have assured there was some column on column impacts. You also shouldn't take things to an extreme on what I have said, as you have seen me say on this thread recently that any random chaotic impact would have produced a deceleration if there was no tampering with the structure. The Verinage demolitions aren't necessarily perfect column on column impacts either.

[ozeco41]

This is not some vague thing- this is real. They produced and made public I presume the first draft two days after 9/11 . I call that foreknowledge in the most friendly of interpretations. Are you saying that it is reasonable to believe that they put together something like that in less than two days ?

The terms of their collaberation as two top professionals would have taken longer than that to work out. 9/11 was a surprise- remember ?
Which leads to two possibilities for surmise.

Since I am on the side of the "goodies" - white hat, white horse and two silver six-shooters in the old western paradigm - I go first.

Remember how academic papers are often written. The first named author is the "recognised name" who can get it published whilst the second person named does the hard graft of writing. Then the BZ paper is a massive simplification. And get your names out there quickly. In academic tactics BZ created attraction and paved the way for later papers.

Pure speculation but possible one or the other had previously done some thinking about WTC, on 9/11 said "now why did that happen?" - quick energy calcs - then a phone call to the other one where Zhou calling Bazant seems more likely to me.

Who knows - the full information may be public knowledge and I could be talking through my white (Roy Rogers style) cowboy hat. And I don't ride horses or sing whilst doing so.

The "baddies" side naturally has poor B and Z in the conspiracy with foreknowledge.

[bill smith]

Less balanced professional and more debunker I think. Watch and learn Readers.

[ozeco41]

Your first sentence here is a large leap in logic.
Thou dost play with words and innuendo/inference Tony. http://conleys.com.au/smilies/nono.gif

Going from step one - leaving out the intermediate steps and stating the final step is not a "leap of wrong logic". Merely economy of writing.

Cheers. :)

[carlitos]

Not only "should have been" - his hypothesis relies on it.

Tony's "Missing Jolt" paper is premised on "column on column axial impact" where columns are the only structural elements capable of developing sufficient resistance in one isolated sub-event which would be identifiable as a "jolt". Quoting from Graeme MacQueen & Tony Szamboti "The Missing Jolt: A Simple Refutation of the NIST-Bazant Collapse Hypothesis"
...so he takes the extreme case allowed by the assumptions in Bazant & Zhou and builds on it.

That extreme has column on column axial contact. It is valid for B & Z to use it as an approximation - it is on the "safe" side when it finds that there was sufficient energy to allow propagation of the global collapse. It is not valid for Tony to assume it.
Brutal. I have zero engineering background, but from a year or so of discussing this topic, I think I understand the absurdity of this pretty well. How could columns that were tilting at several degrees and rotating have "axial column on column" collisions with any columns below them?

Mr Szamboti, are these indeed your assumptions? Axial column on column impact for many / some / all of the columns? How could this have possibly happened?

[Tony Szamboti]

Brutal. I have zero engineering background, but from a year or so of discussing this topic, I think I understand the absurdity of this pretty well. How could columns that were tilting at several degrees and rotating have "axial column on column" collisions with any columns below them?

Mr Szamboti, are these indeed your assumptions? Axial column on column impact for many / some / all of the columns? How could this have possibly happened?

Carlitos, you apparently haven't heard that it has been proven in the past year that the upper section of WTC 1 tilted at most 1 degree if at all before descending. At that small angle there is no significant horizontal shift. Do the trigonometry if you don't believe it.

The upper section did not tilt to the 8 degrees NIST mentions until after it descended a few stories.

This has been validated by many people in the last year, so it is a bogus argument that the columns would miss each other due to a tilt.

[femr2]

Carlitos, you apparently haven't heard that it has been proven in the past year that the upper section of WTC 1 tilted at most 1 degree if at all before descending. At that small angle there is no significant horizontal shift. Do the trigonometry if you don't believe it.

The upper section did not tilt to the 8 degrees NIST mentions until after it descended a few stories.

This has been validated by many people in the last year, so it is a bogus argument that the columns would miss each other due to a tilt.
Tony,

Whilst I agree that vertical drop of all four corners of the upper section of WTC 1 ensued after only ~1 degree of rotation, I note that you are repeatedly attributing this observation to not only support your position, but also seem to be implying that the folk responsible for determining that metric agree with you.

You know this is not the case.

You also know that achimspok has generated much of the rotation data, with some also provided by myself, along with the visualisation models you have in mind.

You are continuing to treat the building as a rigid entity. It was not.

You are continuing to ignore lateral rotation and even the potential effect of buckling.

Please don't imply your own personal interpretation of information provided to you as being supported by them-there folk, myself in particular.

You are making the same kind of mistakes that others do when applying the Bazant model literally to the towers.

Even with the small initial angle (which of course continued to increase) there is, in my opinion, no logical situation which should result in any significant axial column impacts.

Add to that that core column impacts have to be transmitted through all manner of flexible structure to be traceable at either the NW corner or roofline of the North face and the chances of capturing the kind of *jolts* you are expecting is, in my opinion, not happenin'.

As you also know, we have identified a number of smaller *mini jolts*.

Again, please make it very clear that what you are saying is your own personal interpretation, not one shared by those responsible for determining the metric you are using.

[ozeco41]

Brutal. I have zero engineering background, but from a year or so of discussing this topic, I think I understand the absurdity of this pretty well. How could columns that were tilting at several degrees and rotating have "axial column on column" collisions with any columns below them? It is even more fundamental than that in my explanation. The first step of that logic is to recognise that the top block was moving downwards so there could not be any significant axial contact of column parts.

Recognise that I am drawing a distinct line in the sand to separate the "initial collapse" - the first downwards movement of the top block, from the "global collapse" which followed.

That line is precisely where Tony postulates his "Missing Jolt". The initial collapse has downward movement of the top block and the impact of that with the lower tower to start the global collapse is where Tony looks for a jolt and I say the contact mechanism was not one which would produce a distinct, large, measurable by video scaling jolt. So, as per my previous post:...it does not call for extraordinary thinking.
Recalling that the precursor condition for your lost jolt is that the top block is falling.

Therefore no column on column contact at that time.... ...and therefore considerations of tilt are irrelevant -- but they offer a convenient "red herring" to distract or derail the debate.

The question which then follows is "how did this no axial contact situation arise?" - which has the usual two polarised and opposing answers. :)

[pgimeno]

Carlitos, you apparently haven't heard that it has been proven in the past year that the upper section of WTC 1 tilted at most 1 degree if at all before descending. At that small angle there is no significant horizontal shift. Do the trigonometry if you don't believe it.

The core column sections were three floors high. The relevant tilt angle of the top to consider is not the tilt angle at the start of the descent, but the tilt angle after three floors of descent, which to my knowledge has not been determined. At the start of the release, there could be no axial impact for the simple reason that the columns were initially touching each other.

That alone reveals either Tony's incompetence, dishonesty, or blindness due to wishful thinking, which would be also incompetence.

That exceeds the scope of this thread, though. Tony has me on ignore for the looks of it anyway, but it would be good if someone reminds him when he brings the tilt angle issue again in some other thread.

[pgimeno]

This is not some vague thing- this is real. They produced and made public I presume the first draft two days after 9/11 . I call that foreknowledge in the most friendly of interpretations. Are you saying that it is reasonable to believe that they put together something like that in less than two days ?

Something like what? The first paper was just a bit above one page long and just had a couple of simple equations. See http://www.civil.northwestern.edu/people/bazant/PDFs/Papers/404.pdf, short and simple.

The terms of their collaberation as two top professionals would have taken longer than that to work out. 9/11 was a surprise- remember ?

According to the list of publications (http://www.civil.northwestern.edu/docs/Bazant/publicat.pdf), [BZ] is from 2002 and the first version from 2001 is attributed to Bazant alone. However, in the paper Yong Zhou is also mentioned. Zhou was a Graduate Research Assistant at Bazant's univ., see footnote 3 of [BZ].

The most likely scenario to me is that the discussion happened in Northwestern University, probably the same day 11, and that Bazant alone (or with Zhou's help) put together the first 1 page draft during the next day, to submit it on 13th. No phone involved in this scenario. Writing a 1-page paper with just two simple calculations like the one in there does not take a team nor weeks of research.

And now, focus.

[Tony Szamboti]

The core column sections were three floors high. The relevant tilt angle of the top to consider is not the tilt angle at the start of the descent, but the tilt angle after three floors of descent, which to my knowledge has not been determined. At the start of the release, there could be no axial impact for the simple reason that the columns were initially touching each other.

That alone reveals either Tony's incompetence, dishonesty, or blindness due to wishful thinking, which would be also incompetence.

That exceeds the scope of this thread, though. Tony has me on ignore for the looks of it anyway, but it would be good if someone reminds him when he brings the tilt angle issue again in some other thread.

No, I don't have you on ignore. There just hasn't been much I thought worth responding to from you lately. However, I do have to tell you that anyone using a pseudonym really shouldn't take offense if they aren't responded to, as it isn't considered rude to ignore someone who refuses to tell you their name.

As far as what you are saying here, it sounds like you are trying to say the core column buckling took place over three stories. If that is what you are saying, I have to tell you that the horizontal bracing of the core columns at every floor would preclude that from occurring.

The collapse initiation in WTC 1 started quite evenly at the 98th floor and multi-story buckling is not a possibility there. There should have been an impact between the 99th and 97th floors, and there was little to no tilt angle after a fall of one story.

[carlitos]

No, I don't have you on ignore. There just hasn't been much I thought worth responding to from you lately. However, I do have to tell you that anyone using a pseudonym really shouldn't take offense if they aren't responded to, as it isn't considered rude to ignore someone who refuses to tell you their name..
I again remind you that we are on a discussion forum, where anonymity is the norm, not the exception, and that your requests come off as you just being creepy.

All that said, this particular poster has told you his name in other threads, and yet you still ask. I can see why he thought you had him on ignore or something. Still, you could perhaps click on the user name, before you level accusations like this. This kind of stuff doesn't enhance the credibility you are attempting to build here.

http://img180.imageshack.us/img180/8525/picture3ny.png

[GlennB]

The inertia of the upper section would have assured there was some column on column impacts.

How? How could a column end ever meet its one-time mate when column breakage is a prerequisite for collapse? The column ends are apart by definition and cannot be re-matched without lifting the upper block.

You have always avoided this question. Have a crack at it one day, eh?

[femr2]

it isn't considered rude to ignore someone who refuses to tell you their name.
Bearing in mind that the information (1 degree rotation) was determined by folk who use an online ID, I have noticed that it is only people who do not agree with you whom you demand personal details from.

I'll say this with 100% surety Tony...no matter what *ID* someone uses to present information to you, it does not change the validity of the information. You can agree or disagree, but beyond that identity is utterly irrelevant.

You seem to use it as a way of ignoring what you choose to. Not good.

You have not responded to my request above. If you do not respond, I assume you are ignoring me on the basis of using an ID and therefore should also stop using any information I have provided which you find useful for your own purposes (such as the trace data and core model observations).

[pgimeno]

No, I don't have you on ignore. There just hasn't been much I thought worth responding to from you lately. However, I do have to tell you that anyone using a pseudonym really shouldn't take offense if they aren't responded to, as it isn't considered rude to ignore someone who refuses to tell you their name.

What is that fantasy of me "refusing" to tell you my name? All these messages were directed to you (click the small arrow right of "pgimeno" to check the original):

If that matters to you, *my* full name is Pedro Gimeno Fortea. I did some points about the Verinage in message #1112 that you are not addressing at all.
Remember, my full name is Pedro Gimeno Fortea, if that matters to you. You can look it up in my profile now in case you forget.
Just as a reminder, my whole name is Pedro Gimeno Fortea, as I already told you once. It's even stated in my public profile.
Just as a reminder, since you seem to have cared in past and forgotten in past, my full name is Pedro Gimeno Fortea, from Valencia, ES, as you can readily check in my profile.
Tony, are you that forgetful, or are you outright lying? I'd say after so many reminders, your forgetfulness looks quite willful. My name is Pedro Gimeno Fortea, and I live in Valencia, ES. Not that that should have any relevance, but since I don't care to make it public, I'm telling you (again). You even have been unable to associate pgimeno = PGimeno = P. Gimeno = Pedro Gimeno. That's not rocket science, Tony. Your assertion that I'm "refusing" to tell my name means not only that you haven't used my username as an easy mnemonic hint, but also that you haven't even cared to look up my profile to check, making it easy to assume that you're willfully making up your statement in an attempt to either deceive or despise.

Plus, when you say "it isn't considered rude to ignore someone who refuses to tell you their name", you should speak for yourself only, not in general. I consider rude when someone ignores an argument written by anyone, be it anonymous, a pseudonym or a real name. And your contemptuous attitude speaks lots of yourself.

But I'll give you the benefit of the doubt, again, and think that it's just that you have preconceived ideas that you stick to no matter how many times you're proved wrong. Because, you see, that also explains your attitude of willful forgetfulness.

As far as what you are saying here, it sounds like you are trying to say the core column buckling took place over three stories. If that is what you are saying, I have to tell you that the horizontal bracing of the core columns at every floor would preclude that from occurring.

What I am saying is that it's impossible to have axial column-to-column impacts if there is no column base to impact with another column base. The core columns were three floors high, meaning that there were column bases only every three floors, therefore the upper section had to fall three floors before a column-to-column axial impact was ever possible. Evaluating whether the tilt angle at the release point allowed axial impacts is ludicrous, as there was no column base that could impact another column base.

[Tony Szamboti]

Bearing in mind that the information (1 degree rotation) was determined by folk who use an online ID, I have noticed that it is only people who do not agree with you whom you demand personal details from.

I'll say this with 100% surety Tony...no matter what *ID* someone uses to present information to you, it does not change the validity of the information. You can agree or disagree, but beyond that identity is utterly irrelevant.

You seem to use it as a way of ignoring what you choose to. Not good.

You have not responded to my request above. If you do not respond, I assume you are ignoring me on the basis of using an ID and therefore should also stop using any information I have provided which you find useful for your own purposes (such as the trace data and core model observations).

I am hardly referring to your information in my discussion above, as much of your work is disjointed and nonsensical. Your use of a pseudonym is also problematic. One reason I can think of for that is that it is very possible that numerous people can use the same pseudonym without accountability in any real sense. A real individual would not allow others to speak for him.

It isn't only people who I disagree with as far as my point that pseudonyms reduce the validity of the discussion.

I was referring to measurements taken by Achimspok and David Chandler, both of whom have given their names with Achimspok sharing e-mails using his real name with many involved in this discussion.

[Tony Szamboti]

What I am saying is that it's impossible to have axial column-to-column impacts if there is no column base to impact with another column base. The core columns were three floors high, meaning that there were column bases only every three floors, therefore the upper section had to fall three floors before a column-to-column axial impact was ever possible. Evaluating whether the tilt angle at the release point allowed axial impacts is ludicrous, as there was no column base that could impact another column base.

Okay, so you have given your name in your forum information, but I do have to wonder what your background is for you to be saying what you are. Are you an engineer?

If you do a finite element analysis of a buckling column and animate it you will see that the upper and lower ends contact after the scissor closes. The bifurcation (scissors) can only occur between stories due to horizontal bracing.

Your notion of natural multi-story core column buckling during initiation is not supportable and the fact that this is even being argued is ridiculous.

[DGM]

<derail>Tony....... Happy birthday tomorrow (you old bastard, from one of the same)</derail>


:D

[beachnut]

Funny stuff; tony was the "realcddeal" when he showed up. He quibbles when people destroy his delusions, when he can't figure out their "real" name.

All Engineers, who are not paranoid conspiracy theorists on 911, understand 911 truth's moronic "real cd deal" is nonsense. All engineers, who are not paranoid conspiracy theorists, understand how Bazant's work applies to the real world.

Now known, with solid proof for 9 years, presenting your real name does not make your delusions come true. If you have paranoid delusions of CD, using your real name may require a name change when you discover reality.

If Tony's paranoid name fetish was true, the only people with rational conclusions on 911 would be those with fake names. For me the "realcddeal" will be Tony; when I see his name, I can only see his delusion of cd, the realcddeal.

It was funny the first time I saw it, like a statement, "I don't need evidence", I have the realcddeal. Evidence free for 9 years, the 911 truth cult members (albeit, a group with no real group membership; they all have different nut case ideas based on nothing but junk and fail to comprehend the same) attack Bazant's model and expose their failure. 9 years.

I need them (tony,femr2, majortom) to publish letters to real journals, I miss seeing real engineers, besides myself, using nonsense and delusional to describe 911 truth claims, like Tony's and his buddies pushing the cd delusion past 9 years with no progress, or evidence. Publish NOW! Please.


Applicability of Bazant's model to the real world; the better question is,
Applicability of 911 truth's work to the real world?
Answer is,
NONE!

[GlennB]

If you do a finite element analysis of a buckling column and animate it you will see that the upper and lower ends contact after the scissor closes. The bifurcation (scissors) can only occur between stories due to horizontal bracing.


Do they? Or do they merely overlap in 2-D?

If a buckled column snaps or detaches at the weld while buckled how can the two ends ever again make contact in 3-D ?

Please explain. You never have so far, despite many requests.

[Tony Szamboti]

Do they? Or do they merely overlap in 2-D?

If a buckled column snaps or detaches at the weld while buckled how can the two ends ever again make contact in 3-D ?

Please explain. You never have so far, despite many requests.

Why don't you try it and see for yourself?

[Tony Szamboti]

I miss seeing real engineers, besides myself, using nonsense...
Don't blame me for your use of the English language as you actually wrote this. But I am glad to see you finally got it right.

Unfortunately for those like you who have chosen to live in a fairytale land, most engineers come to the realization that the twin tower and bldg. 7 collapses were the results of controlled demolitions after they have actually looked into it. Reality isn't all that hard to take Beachnut. You should try it and stop your whining to try and keep others with you in fairytale land.

[GlennB]

Why don't you try it and see for yourself?

Pitiful evasion noted.

If you have tried it you can show us the results. Fire away.

[pgimeno]

Okay, so you have given your name in your forum information, but I do have to wonder what your background is for you to be saying what you are. Are you an engineer?

First you wanted to know my name, now you want to know my background. Will you ask me next if I have dual citizenship? My credit card number? My sexual preferences? I suppose you won't ask me my religion if I answer I do have dual citizenship, but if I answer I don't, will you? Will any of the answers affect my arguments, or merely help your despise?

The answer to your question is in the OP.

If you do a finite element analysis of a buckling column and animate it you will see that the upper and lower ends contact after the scissor closes. The bifurcation (scissors) can only occur between stories due to horizontal bracing.

Is that the only way columns fail in the real world?

Here's a failed column from the 8th floor of WTC 5 (from FEMA 403 chapter 4 (http://www.fema.gov/pdf/library/fema403_ch4.pdf) p.15):

http://www.formauri.es/personal/pgimeno/xfiles/lordkiri/ch4-021.jpg

Imagine that column being further crushed down from the top. Would you expect an axial column-to-column impact at some point?

Is the shown effect on that column obtained in FEA simulations? Will a FEA accurately reproduce the behavior of that column with respect to impact mode?

Your notion of natural multi-story core column buckling during initiation is not supportable and the fact that this is even being argued is ridiculous.
I never said multi-story buckling, that's once again a preconception of yours to which you seem to be stuck.

[ergo]

Happy Birthday, Tony :) if it is your birthday...

[beachnut]

... , most engineers come to the realization that the twin tower and bldg. 7 collapses were the results of controlled demolitions after they have actually looked into it. ...
Using truther math, 0.001 percent of all engineers is "most". You guys have delusions, and you have delusions about who believes your delusions.

Got a list of engineers signing a statement that WTC1/2/7 are CDs? No!

Write your delusions down and send them to Bazant. Publish Tony, stop telling lies of most engineers believe your idiotic CD delusion, and do something. 9 years ago Passengers on Flight 93 figured out 911 in minutes; you have failed for 9 years. Send Bazant a note and break the inside job wide open.

In 911 truth delusion-land, most = 0.001 percent ; love truther math.
I bet Bazant will call your work nonsense and delusional, exactly like Heiwa's work. When will you write the letter and correct Bazant's model?

[Tony Szamboti]

First you wanted to know my name, now you want to know my background. Will you ask me next if I have dual citizenship? My credit card number? My sexual preferences? I suppose you won't ask me my religion if I answer I do have dual citizenship, but if I answer I don't, will you? Will any of the answers affect my arguments, or merely help your despise?

Knowing someone's real name and background does have something to do with credibility in a discussion.

In this situation dual citizenship might cause a motivation beyond a desire for the plain truth of the matter and might be a conflict of interest. At that point one would need to ascertain what a person's true motivation was from other information. Most people wonder about the other party's motivations when engaged in a debate with them. It is only natural.

Sexual preference and religious affiliation should not cause a conflict of interest on this issue and wouldn't affect one's credibility. Obviously you were joking about credit card number as that does not affect anything.

I never said multi-story buckling, that's once again a preconception of yours to which you seem to be stuck.

You seemed to be implying multi-story buckling as you said what mattered was where the upper section was after three stories of the fall concerning any horizontal shift from a tilt.

I say it matters where it was after one story, that the 1 degree or less tilt would not produce a significant horizontal misalignment, and that there would certainly be a significant amount of column on column impact and there would have been a serious deceleration, if the collapse were natural.

The column you chose from WTC 5 isn't representative of what we are discussing.

[DGM]

Knowing someone's real name and background does have something to do with credibility in a discussion.

In this situation dual citizenship might cause a motivation beyond a desire for the plain truth of the matter and might be a conflict of interest. At that point one would need to ascertain what a person's true motivation was.



What about someones association with a group that has been known to lie and has a known political agenda?

[Grizzly Bear]

I say it matters where it was after one story, that the 1 degree or less tilt would not produce a significant horizontal misalignment, and that there would certainly be a significant amount of column on column impact and there would have been a serious deceleration, if the collapse were natural.

The column you chose from WTC 5 isn't representative of what we are discussing.
It is actually to an extent in so much that the slightest bit of "tilt" means that the load paths carrying through the columns is no longer axial. It introduces moment about the point of "rotation" where the tilt is initiating. In WTC 5 it didn't even take a separation between column ends to do this... It was already misaligned. The result of that is readily apparent in that the whole of the piece is tilted off to the right (meaning you can kiss it's integrity good-bye). Once again, you need to understand where Bazant's model works and where the scope of it ends, you've been told this countless times and it's affecting your responses to other people who are expanding beyond the simplified modeling techniques.

And a slight shift of topic... Happy Birthday :)

[Tony Szamboti]

It is actually to an extent in so much that the slightest bit of "tilt" means that the load paths carrying through the columns is no longer axial. It introduces moment about the point of "rotation" where the tilt is initiating. In WTC 5 it didn't even take a separation between column ends to do this... It was already misaligned. The result of that is readily apparent in that the whole of the piece is tilted off to the right (meaning you can kiss it's integrity good-bye). Once again, you need to understand where Bazant's model works and where the scope of it ends, you've been told this countless times and it's affecting your responses to other people who are expanding beyond the simplified modeling techniques.

And a slight shift of topic... Happy Birthday :)

With the amount of tilt involved the load would have been mostly axial and the misalignment would have been quite small and would not have precluded a jolt in a natural collapse. I do understand the Bazant limiting case argument some of you guys try to make but it doesn't make a difference to whether or not there should have been a jolt in a natural collapse. There should have been one based on the geometry of the fall and the structure above and below.

Thank you and the others here for the birthday wish.

[Tony Szamboti]

What about someones association with a group that has been known to lie and has a known political agenda?

I think that would be a case where one would need to know more about the individual and just what their interaction was with that group, what that group's motivation and agenda was and whether or not that person was involved in any fraudalent information or lying or knew about it and did nothing etc..

What you are talking about here is a complicated situation where one would need to know a lot more about the circumstances to make a judgement. I don't think you can make a sweeping guilt by association verdict and be confident of its accuracy.

[beachnut]

Any misalignment would have been quite small and would not have precluded a jolt in a natural collapse. I do understand the Bazant limiting case argument some of you guys try to make but it doesn't make a difference to whether or not there should have been a jolt in a natural collapse. There should have been one based on the geometry of the fall and the structure above and below.

Thanks for the birthday wish.
What reality based journal has your jolt paper (how does it dovetail with Bazant's model)? Which ones did you submit it to? Happy birthday Tony, happy 9 years of failed opinions on 911 issues. How does your jolt work in with Bazant's paper, and have you written a letter to explain it to Bazant? Your "most" engineer statement was a lie, but it is interesting to note, not one of the "most" engineers has written a paper in a real engineering journal. "most"? Most engineers do not support the CD nonsense - add that to your list of delusions. Will you write your concerns to Bazant?

[Tony Szamboti]

What reality based journal has your jolt paper? Which ones did you submit it to? Happy birthday Tony, happy 9 years of failed opinions on 911 issues. How does your jolt work in with Bazant's paper, and have you written a letter to explain it to Bazant? Your "most" engineer statement was a lie, but it is interesting to not not one of the "most" engineers has written a paper in a real engineering journal. "most"? Most engineers do not support the CD nonsense - add that to your list of delusions. Will you write your concerns to Bazant?

I have written Dr. Bazant explaining my concerns.

[beachnut]

I have written Dr. Bazant explaining my concerns.
When will we see the results? Good job!

[ozeco41]

Recalling that the OP title is "Applicability of Bazant's model to the real world" can I address Tony's recent post where he makes this important point:...I say it matters where it was after one story, that the 1 degree or less tilt would not produce a significant horizontal misalignment, and that there would certainly be a significant amount of column on column impact and there would have been a serious deceleration, if the collapse were natural....
I agree with that observation up to the last five words which I have put a rule through. The claim "...if the collapse were natural..." does not follow from the preceding. Leave that issue aside for a short while.

The critical issue is the extent if any of axial contact. And Bazant (in Bazant and Zhou ["BZ"]) makes the assumption which is conservative in the context of the BZ model that there was axial contact between the upper and lower parts of the columns. Tony's "Missing Jolt" hypothesis relies on that axial contact to offer resistance producing a jolt. In the absence of such a jolt Tony concluded (my words to the effect of) "something removed the columns therefore demolition".

Opposing both Tony's position and the Bazant assumption of axial contact I have several times made a bold claim. The latest version being: It is even more fundamental than that in my explanation. The first step of that logic is to recognise that the top block was moving downwards so there could not be any significant axial contact of column parts.

Recognise that I am drawing a distinct line in the sand to separate the "initial collapse" - the first downwards movement of the top block, from the "global collapse" which followed.

That line is precisely where Tony postulates his "Missing Jolt". The initial collapse has downward movement of the top block and the impact of that with the lower tower to start the global collapse is where Tony looks for a jolt and I say the contact mechanism was not one which would produce a distinct, large, measurable by video scaling jolt. So, as per my previous post:...and therefore considerations of tilt are irrelevant -- but they offer a convenient "red herring" to distract or derail the debate.

The question which then follows is "how did this no axial contact situation arise?" - which has the usual two polarised and opposing answers. :) At that stage I did not elaborate as to what were the two answers to "how did this no axial contact situation arise?" Naturally I had in mind: No demolition; AND Demolition.

Remembering the premise "...there could not be any significant axial contact of column parts..." I will explore each of those options briefly:

The "no demolition" case relies on the premise that the top block is falling so the top parts of columns are already bypassing the bottom parts. It matters not how they got into that relationship. Heat affected buckling as per the recent picture posted by pgimeno, inwards "folding" of the columns pulled inwards by sagging floor trusses. the detail matters not. The key point is that the top bit of column is bypassing the bottom bit. AND there is no mechanism to put the two parts back into axial contact. AND, even if there was, the column ends are near certainly rounded or distorted so that axial transfer of load would cause the two to "slip off". And, for the outer tube columns, that bypassing relationship will continue throughout the collapse. Same goes for core columns but the explanation is more complex.

Now let's look at the demolition case where Tony's jolt hypothesis looks for axial contact and finds it missing. I understand that this is seen to come about because a section of column has been cleanly removed. Possibly by a combination of "cutter" and "kicker" charges thereby leaving a clear gap in the column but with the top bit aligned more or less over the bottom. If I have that wrong Tony can put me right on the actual mechanism he has in mind for his jolt. So, given this scenario and the top block falling we have two possibilities: The top block falls the distance of the gap and impacts column on column more or less axially. Would that not produce the jolt which Tony cannot find? OTHERWISE To avoid the need for a jolt - all or most of the top portions of cut columns have to miss their lower portion counterparts to ensure that there is no detectable jolt thus matching Tony's findings. How does the demolition scenario cause most columns to fall missing their lower parts?

Whatever the outcome of discussions of these possibilities I suggest that this thread has: Identified or clarified limitations of applicabiilty of BZ to the WTC Twin Towers collapse; AND Identified where the paper "The Missing Jolt..." relies on parts of BZ which are inapplicable.

...and going that far will do me for now. :)

[Tony Szamboti]

Remembering the premise "...there could not be any significant axial contact of column parts..." I will explore each of those options briefly:

The "no demolition" case relies on the premise that the top block is falling so the top parts of columns are already bypassing the bottom parts. It matters not how they got into that relationship. Heat affected buckling as per the recent picture posted by pgimeno, inwards "folding" of the columns pulled inwards by sagging floor trusses. the detail matters not. The key point is that the top bit of column is bypassing the bottom bit. AND there is no mechanism to put the two parts back into axial contact. AND, even if there was, the column ends are near certainly rounded or distorted so that axial transfer of load would cause the two to "slip off". And, for the outer tube columns, that bypassing relationship will continue throughout the collapse. Same goes for core columns but the explanation is more complex.

The column from WTC 5 is not representative of those collapsing over an entire floor such as what would have needed to occur in the collapse of WTC 1 where it uniformly collapsed at the 98th floor.

The columns and beams would still be interconnected during buckling and the rounding you describe at the upper and lower plastic hinges would not cause a light load and slip off. The force of impact would have caused plastic deformation at contact and produced a large deceleration.



Now let's look at the demolition case where Tony's jolt hypothesis looks for axial contact and finds it missing. I understand that this is seen to come about because a section of column has been cleanly removed. Possibly by a combination of "cutter" and "kicker" charges thereby leaving a clear gap in the column but with the top bit aligned more or less over the bottom. If I have that wrong Tony can put me right on the actual mechanism he has in mind for his jolt. So, given this scenario and the top block falling we have two possibilities: The top block falls the distance of the gap and impacts column on column more or less axially. Would that not produce the jolt which Tony cannot find? OTHERWISE To avoid the need for a jolt - all or most of the top portions of cut columns have to miss their lower portion counterparts to ensure that there is no detectable jolt thus matching Tony's findings. How does the demolition scenario cause most columns to fall missing their lower parts?

My theory, based on observation and measurements, is that at the time the first impact should have occurred the lower portion of the upper section was being broken up by unnatural causes and therefore was unable to apply a shock load. Afterward I think the lower section was being weakened by similar unnatural causes precluding high g impacts and deceleration by the upper section for the nine stories we could measure the fall.

The small amount of resistance observed (0.3g) would be generated by just 10% of the original structure still having some integrity but which only provided 30% of the support necessary for the static load, which then simply fell through it at about 0.7g acceleration.

[Tony Szamboti]

When will we see the results? Good job!

You will have to ask him. He seems to be slow coming around to the reality of the situation like you.

[beachnut]

You will have to ask him. He seems to be slow coming around to the reality of the situation like you.
You are full of delusions.

When will you list your most engineers? lol, you are funny; after 9 years of complete failure you continue supporting the failed CD delusion. List the engineers and produce their signature saying they support WTC1/2/7 CD. I recommend not holding your breath. OR, produce any evidence at all to support your idiotic CD delusion. OR, admit you lied about most engineers support your CD conclusion on WTC1/2/7. All the engineers I graduated with don't support your theory; oops, there goes most down the drain.

On topic; how does your jolt super theory dovetail with Bazant's model?

[Tony Szamboti]

You are full of delusions.

When will you list your most engineers? lol, you are funny; after 9 years of complete failure you continue supporting the failed CD delusion. List the engineers and produce their signature saying they support WTC1/2/7 CD. I recommend not holding your breath. OR, produce any evidence at all to support your idiotic CD delusion. OR, admit you lied about most engineers support your CD conclusion on WTC1/2/7. All the engineers I graduated with don't support your theory; oops, there goes most down the drain.

On topic; how does your jolt super theory dovetail with Bazant's model?

At least 95% of engineers I talk to about this, who then do their own research, soon come to the realization that the twin tower and WTC 7 collapses were actually caused by controlled demolition and not as a result of fire and damage. An old colleague of mine even called a few weeks ago to talk about it. He said he had read my papers and after investigating the collapses himself, in other ways, he realized that the collapses were indeed due to controlled demolitions.

[carlitos]

You are full of delusions.

When will you list your most engineers? ?

At least 95% of engineers I talk to about this, who then do their own research, soon come to the realization that the twin tower and WTC 7 collapses were actually caused by controlled demolition and not as a result of fire and damage.

Seriously, Tony, you are a big fan of real names and real qualifications being disclosed. Please elaborate.

[Major_Tom]

Pgimeno, I have given quotes by Dave, R Mackey and Newton's Bit in which the describe an intact upper structure riding the debris pile to earth like it is riding a magic carpet before "crushing up". You cannot see a mistake in that? Will we regress to conjuring up the famous upper block again?

>>>>>>>>>>>>>>..


If you want to know the most about the first 12 ft of fall of both the north facade and the antenna of WTC1, why not just measure them using the highest quality video and the most precise tracking methods possible?

Already done:

Tracking by achimspok

http://img101.imageshack.us/img101/4753/image00029.png

The Sauret drop curve of NW corner is shown in blue. It's corresponding velocity curve is shown in purple. We see there is an abrupt change in the slope of the velocity curve that can be traced back to frame 222. This is the release event for the NW corner.

The acceleration (slope of the velocity curve) quickly changes through frame 222. The traced point is now falling at 0.5g to 1.0g. There is one measured velocity reduction around frame 250. In frame 250 the positional data shows the NW corner has fallen about 3 ft.

In the pre-release region we can carefully study changes in the positional data as far ahead of frame 222 as we wish, looking for the earliest detectable deformations.

The Sauret drop curve of the black-white transition point on the antenna is in yellow. It's corresponding velocity curve is in light green. We see movement from frame 140, yet the velocity curve does not take off with a 0.5g to 1.0g acceleration until frame 215. The release event is around frame 215.

In the pre-release region we see considerable movement before frame 215. Over 2 feet of downward displacement is measure in the antenna between frames 130 and 215.

In the post-release region we detect one velocity reduction. How far has the traced point dropped when the reduction occurs? It happens around frame 228, when the positional data shows a 3 ft drop.

Notice that there is no such thing as a "global velicity reduction". The NW corner experiences velocity reductions at different moments than the antenna does. The concept of "velocity reduction" depends on the point that is traced since we can see simlar reductions in both the NW corner and the antenna, but at different times.


Tracking by femr

NW corner drop velocity reductions

http://femr2.ucoz.com/photo/6-0-372-3

red is drop in ft
orange is velocity


>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

On a different forum I have watched a few people detect these jolts independently, so this is not just one person's guess. Can the pattern in the velocity reductions be a signature of some type of early collisions?

[GlennB]

If you do a finite element analysis of a buckling column and animate it you will see that the upper and lower ends contact after the scissor closes. The bifurcation (scissors) can only occur between stories due to horizontal bracing.


Do they? Or do they merely overlap in 2-D?

If a buckled column snaps or detaches at the weld while buckled how can the two ends ever again make contact in 3-D ?

Please explain. You never have so far, despite many requests.

Bump for Tony. We're still waiting for an answer, not a hand-wave.

[Tony Szamboti]

Pgimeno, I have given quotes by Dave, R Mackey and Newton's Bit in which the describe an intact upper structure riding the debris pile to earth like it is riding a magic carpet before "crushing up". You cannot see a mistake in that? Will we regress to conjuring up the famous upper block again?

>>>>>>>>>>>>>>..


If you want to know the most about the first 12 ft of fall of both the north facade and the antenna of WTC1, why not just measure them using the highest quality video and the most precise tracking methods possible?

Already done:

Tracking by achimspok

http://img101.imageshack.us/img101/4753/image00029.png

The Sauret drop curve of NW corner is shown in blue. It's corresponding velocity curve is shown in purple. We see there is an abrupt change in the slope of the velocity curve that can be traced back to frame 222. This is the release event for the NW corner.

The acceleration (slope of the velocity curve) quickly changes through frame 222. The traced point is now falling at 0.5g to 1.0g. There is one measured velocity reduction around frame 250. In frame 250 the positional data shows the NW corner has fallen about 3 ft.

In the pre-release region we can carefully study changes in the positional data as far ahead of frame 222 as we wish, looking for the earliest detectable deformations.

The Sauret drop curve of the black-white transition point on the antenna is in yellow. It's corresponding velocity curve is in light green. We see movement from frame 140, yet the velocity curve does not take off with a 0.5g to 1.0g acceleration until frame 215. The release event is around frame 215.

In the pre-release region we see considerable movement before frame 215. Over 2 feet of downward displacement is measure in the antenna between frames 130 and 215.

In the post-release region we detect one velocity reduction. How far has the traced point dropped when the reduction occurs? It happens around frame 228, when the positional data shows a 3 ft drop.

Notice that there is no such thing as a "global velicity reduction". The NW corner experiences velocity reductions at different moments than the antenna does. The concept of "velocity reduction" depends on the point that is traced since we can see simlar reductions in both the NW corner and the antenna, but at different times.


Tracking by femr

NW corner drop velocity reductions

http://femr2.ucoz.com/photo/6-0-372-3

red is drop in ft
orange is velocity


>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

On a different forum I have watched a few people detect these jolts independently, so this is not just one person's guess. Can the pattern in the velocity reductions be a signature of some type of early collisions?

What would be colliding 3 feet into the drop?

[Tony Szamboti]

Bump for Tony. We're still waiting for an answer, not a hand-wave.

There is nothing hard about predicting why there would be little misalignment of the plastic hinges at the ends of buckled columns in a gravity drop, as there would need to be significant lateral forces to cause the columns to be moved out of alignment.

The small tilt of WTC 1 does not cause the kind of lateral force necessary, especially when all of the columns are still interconnected and the entire upper section would need to shift sideways.

As I already stated, the tilt does not produce the misalignment necessary for the columns to miss each other by its rotation either. A 1 degree tilt produces less than an inch of horizontal shift over 207 feet.

[femr2]

there would need to be significant lateral forces to cause the columns to be moved out of alignment.
The perimeter panels shifted enough such that the upper section passed either in front of or behind the lower perimeter panels.

That can be confirmed by observation of video.

The amount of lateral shift required for such is enough to state that similar levels of lateral shift could be present within the core.

Also observable from video is the global lateral shift of each tower upon initiation. Without *instant* initiation it is obvious that all actions will create lateral forces.

Initiation was not *instant*, with antenna shift numerous seconds before release.

Add to this the fact that enourmous stored strain is released upon any seprataion of upper and lower members and it's clear that lateral *springing* is quite possible.

the entire upper section would need to shift sideways.
Shift to the East beginning around the time of the Sauret footage camera shake.

As I already stated, the tilt does not produce the misalignment necessary for the columns to miss each other by its rotation either.
You are treating the structure as a rigid virtual entity.

[carlitos]

An old colleague of mine even called a few weeks ago to talk about it. He said he had read my papers and after investigating the collapses himself, in other ways, he realized that the collapses were indeed due to controlled demolitions.
Does your colleague have a name? What are his qualifications in engineering? How about his citizenship?

You are full of delusions.

When will you list your most engineers? ?

At least 95% of engineers I talk to about this, who then do their own research, soon come to the realization that the twin tower and WTC 7 collapses were actually caused by controlled demolition and not as a result of fire and damage.

Seriously, Tony, you are a big fan of real names and real qualifications being disclosed. Please elaborate.

Dodge noted. "At least 95%" means that there are at least 19 engineers who believe in
"controlled demolition" of the twin towers and the Salomon Brothers building? Can you please list them for us? Because, I will be candid here - I don't believe you. I think that you are exaggerating. Why not encourage these engineers to register here and discuss the issue with other engineers?

[beachnut]

At least 95% of engineers I talk to about this, who then do their own research, soon come to the realization that the twin tower and WTC 7 collapses were actually caused by controlled demolition and not as a result of fire and damage. An old colleague of mine even called a few weeks ago to talk about it. He said he had read my papers and after investigating the collapses himself, in other ways, he realized that the collapses were indeed due to controlled demolitions.
Pure nonsense. You can't even get Bazant to return your email.

Your movement has less than 0.001 percent of all engineers. You call this most, but like your CD delusion, it is a delusion you have.

Hope Bazant answers your email/letter; can't wait to see what he says about your realcddeal. Best of luck. Why does using Bazant's model give a time of collapse very close to the WTC towers; why does using simple physics give a collapse time for a gravity collapse close to what happen on 911? Why are models applicable to reality? Because they are models. Models!

If you had reality based engineering support you would have evidence. Only a few fringe engineers, less than 0.001 percent of us, fall for the lies and delusions you spin, evidence free, unable to publish in real journals because the nonsense and delusional claims would be exposed.

List those engineers - the most. funny stuff.
Again:
On topic; explain how your jolt dovetails with Bazant's model?

[carlitos]

As I already stated, the tilt does not produce the misalignment necessary for the columns to miss each other by its rotation either. A 1 degree tilt produces less than an inch of horizontal shift over 207 feet.
OK, as I stated I'm no engineer, but how did you figure this? I calculated it a few different ways, and I figure it would shift by somewhere between 1.5 and 3 feet. Am I wrong?

Plus, that only talks about horizontal displacement, and the towers had three dimensions, not two.

[pgimeno]

Knowing someone's real name and background does have something to do with credibility in a discussion.

Knowing the background would help in case of appeals to self-authority, not for plain logic or fact-checking or other kinds of arguments. Knowing the name does not help in any way, except maybe if you are presuming bad faith in the stated background, as an aid to research it. But if they claim to be in your field, it should be easy to expose them with specialized questions without the need to know the name, shouldn't it? Say, tfk, who refuses to tell his whole name, do you have any doubts that he's an engineer? It should be easy for you to expose him if he isn't.


In this situation dual citizenship might cause a motivation beyond a desire for the plain truth of the matter and might be a conflict of interest.

Oh, yes it MIGHT, but it also MIGHT NOT be the case, and as you say yourself,
What you are talking about here is a complicated situation where one would need to know a lot more about the circumstances to make a judgement. I don't think you can make a sweeping guilt by association verdict and be confident of its accuracy.
Since knowledge about anyone's personal circumstances usually goes out of the scope of most or all threads about 9/11 in forums, the safest, less smearing, less defaming and most rational and polite approach is to avoid asking. Which you failed to do, making you seem to have an intention of smearing and defaming.


At that point one would need to ascertain what a person's true motivation was from other information. Most people wonder about the other party's motivations when engaged in a debate with them. It is only natural.

It may be natural for some to wonder, but not to ask, when that's off topic and when the context is a forum where anonymity and privacy are a right and, as Carlitos already said, the norm and not the exception.


Obviously you were joking about credit card number as that does not affect anything.

Neither does the name, but you don't seem to agree. Would the validity of my arguments change if my name was Jaime Soler instead of Pedro Gimeno? And if my credit card number started with 9 instead of 0?


I say it matters where it was after one story, that the 1 degree or less tilt would not produce a significant horizontal misalignment, and that there would certainly be a significant amount of column on column impact and there would have been a serious deceleration, if the collapse were natural.

Correct me if I'm wrong, but the 1 degree or less of tilt is for the instant of release, not for the instant of first possible column impact, right? Do you happen to know the tilt at that point?


The column you chose from WTC 5 isn't representative of what we are discussing.
It's a random sample of how a failure can occur. It's due to fire alone, so it's probably creep that caused it. The NIST simulation showed how creep had an important influence in many core columns exceeding their capacity as it did in WTC5, so I don't think it can be left out as an example.