The Collapse of WTC1 and 2

[coughymachine]

Consider this hypothetical scenario:

A decision has been made to bring a WTC-type tower down in a controlled manner. The reasons are legitimate and irrelevant.

Time is taken to prepare the building in the proper way and the site is evacuated in advance.

If all of the core columns were blown simultaneously on one floor - say the 80th - would the building collapse as the towers did on 9/11?

If the collapse mechanism couldn't be replicated by the simultaneous removal of the core columns at one floor, could it be replicated by simultaneously removing the core columns at two floors? If not, how many?

If the collapse mechnism couldn't be replicated, why not?

I started having a similar conversation with one of your members in another forum but, unfortunately, that ended before I got to grips with his line of reasoning.

[gumboot]

I think it's possible, but not guaranteed.

What does this have to do with "the collapse of WTC1 and 2" (the title of this thread)?

-Gumboot

ETA. Welcome to the forums.

[Mancman]

Blowing away all the core columns at once would make the top of the buildings drop straight down.

This didn't happen. The towers leant. The failure of the perimeter walls initiated the collapsed, not the cores.

[jhunter1163]

Most likely, yes, the towers would collapse in the same way. Inertia and all, you know. A building the size of the WTC has tremendous inertia, and pretty much COULD ONLY FALL in the manner seen on 9/11. Someone on this board, probably R. Mackey, calculated how much lateral energy would be required to make the towers topple over rather than collapse straight down. I don't remember the figures, but the impact of a fully loaded 767 wasn't nearly enough.

[Dave Rogers]

If all of the core columns were blown simultaneously on one floor - say the 80th - would the building collapse as the towers did on 9/11?

In how much detail do you want to replicate the 9/11 collapse mechanism? In particular, are you trying to reproduce the inward bowing of the perimeter columns prior to collapse, and their inward movement as the collapse initiated? If so, no it wouldn't - there would be no inward bowing (nothing to cause it), and I suspect that if the core columns were removed and the floor trusses remained initially intact, then the perimeter columns would be restrained from collapsing inwards.

If the collapse mechanism couldn't be replicated by the simultaneous removal of the core columns at one floor, could it be replicated by simultaneously removing the core columns at two floors? If not, how many?

If the collapse mechnism couldn't be replicated, why not?

I suspect the latter for the reasons given above, though there are plenty of people here better qualified to judge than I am.

Dave

[gumboot]

Just want to point out that I took "replicating collapse" to mean the vertical global collapse we saw on 9/11. If you mean more specifically, in particular the collapse mechanism, then Dave Roger is precisely correcting in pointing out you cannot replicate the 9/11 collapse by destroying core columns as the 9/11 collapse was initiated in the floor trusses, not the core.

-Gumboot

[einsteen]

The point is that he wonders if you could reprocude the collapse by blowing up the columns of one story (core and maybe even the perimeter columns), he is interested in the post-collapse initiation process.

The official story indeed says: yes

[Architect]

No, it doesn't.

Dropping the core would not explain the deformation and buckling failure of the external envelope.

[gumboot]

The point is that he wonders if you could reprocude the collapse by blowing up the columns of one story (core and maybe even the perimeter columns), he is interested in the post-collapse initiation process.

The official story indeed says: yes



Let's wait for him/her to clarify for himself/herself.

To be precise, the NIST study seems to indicate that if you removed four or five floors of the tower at once you would get a global collapse.

-Gumboot

[ref]

The point is that he wonders if you could reprocude the collapse by blowing up the columns of one story (core and maybe even the perimeter columns), he is interested in the post-collapse initiation process.

The official story indeed says: yes

Once the upper mass and structure of the WTC drops to the below structure the like of WTC, it will collapse. Didn't Bazant calculate, that only a drop of 0,5 meters for the upper part would have been enough to produce the result we all saw.

[coughymachine]

I think it's possible, but not guaranteed.

What does this have to do with "the collapse of WTC1 and 2" (the title of this thread)?

-Gumboot

ETA. Welcome to the forums.
Thanks for the welcome.

The relevance is simply that the hypothetical is based around a building similar to either of the twin towers. I want to try to understand whether there would be any practical difference, in terms of the resulting collapse mechanism, between the initiating event described by NIST and a blast event as set out in the hypothesis.

[gumboot]

Thanks for the welcome.

The relevance is simply that the hypothetical is based around a building similar to either of the twin towers. I want to try to understand whether there would be any practical difference, in terms of the resulting collapse mechanism, between the initiating event described by NIST and a blast event as set out in the hypothesis.



What you need to appreciate is that the NIST collapse findings indicate a collapse initiation around the floor trusses and the exterior columns.

Your theoretical scenario is based around failure (due to explosives) of the core columns.

I think it's certainly true that the consensus view is a total failure of one floor would result in a global collapse much like we saw on 9/11.

Would removing just the core at one floor result in an entire floor failure?

Probably, but I don't know. The weight division was meant to be 50/50 and a failure of the exterior columns on 9/11 caused a core failure, so I suppose logically a core failure would result in an exterior column failure.

-Gumboot

[coughymachine]

No, it doesn't.

Dropping the core would not explain the deformation and buckling failure of the external envelope.
Presumably, without a core to attach to, the trusses would sag and deform the perimeter.

[The Doc]

http://video.google.com/videoplay?docid=-5405555553528290546

The above video clearly shows the perimeter columns of the World Trade Center bow inwards before the collapse. This was due to the sagging floor trusses pulling them inwards as they sagged further and further.

To replicate the collapse of the towers, you would somehow need to get the floor trusses to sag enough to pull those perimeter columns inward. Fire will do this, explosives and thermite will not.

Blowing all the core columns on one floor of the tower would also create a visible and audible explosion outside of the trade centers. This was not seen on 9/11.

[Architect]

Let's wait for him/her to clarify for himself/herself.

To be precise, the NIST study seems to indicate that if you removed four or five floors of the tower at once you would get a global collapse.

-Gumboot

Point me in the direction of that, please; a (so far) polite young chap at LCF is questioning me on it and I explained that one would have to fully model it to know. Obviously I don't want to waste his time if someone has done it already.

[Dave Rogers]

Thanks for the welcome.

The relevance is simply that the hypothetical is based around a building similar to either of the twin towers. I want to try to understand whether there would be any practical difference, in terms of the resulting collapse mechanism, between the initiating event described by NIST and a blast event as set out in the hypothesis.

The consensus that seems to be emerging, then, is that specific observables relating to the collapse initiation would be visibly different, but that once the collapse had commenced the overall behaviour would be similar (not necessarily identical - the blast hypothesis would need to be asymmetrical to produce the observed rotations of both falling sections). This is consistent with the opinion that NIST were correct to study collapse initiation in detail but not to devote similar effort to modelling the resulting collapse, although I suspect that it would be a circular argument to suggest that one point justifies the other.

Oh yes - welcome to the forum from me too. You've picked an interesting topic to come in with.

Dave

[The Doc]

Presumably, without a core to attach to, the trusses would sag and deform the perimeter.

They wouldn't "sag" so to speak. Sagging is a result of the metal bending. Not breaking.

[Architect]

Presumably, without a core to attach to, the trusses would sag and deform the perimeter.

Oversimplification. The trusses would collapse.

[coughymachine]

I think it's certainly true that the consensus view is a total failure of one floor would result in a global collapse much like we saw on 9/11.
This is the point I wanted to clarify.

[coughymachine]

Oversimplification. The trusses would collapse.
You're right - I'm a bit loose with my terminology here.

What I meant to say was that, with the core removed, the trusses would be lost and the perimeter column would have been unable to support the weight of the building above the 'event'.

In such circumstances, the upper portion would have fallen x number of floors without or with limited resistance. In your opinion, if this wouldn't have led to a similar 'global collapse', how might it have looked or behaved differently?

[Architect]

Originally Posted by gumboot http://forums.randi.org/helloworld2/buttons/viewpost.gif (http://forums.randi.org/showthread.php?p=2622224#post2622224)
I think it's certainly true that the consensus view is a total failure of one floor would result in a global collapse much like we saw on 9/11.


I disagree, but am more than happy to be corrected. These were my thoughts on the issue at LCF, albeit that I was given a hypothetical scenario of between four and six floors being removed.



That's an interesting question.

Firstly, bear in mind that the floor structure provides bracing to the external envelope. We'd therefore have to model whether the omission of the cross bracing over 4-6 floors would destabilise the envelope. This isn't as straightforward as it sounds because of the robust nature of the external frame and the staggered arrangement of the panels, which would serve to help redistribute loads.

The failure mechanism under such circumstances would be buckling of the external facade. The NIST, Arup, and Edinburgh papers all make the case that pull on the deformed trusses was involved in the initiation of the buckling. So if the facade were to "span" the 4 to 6 floor section, buckling might not occur. On the other hand, the killer would probably be wind loadings as these place complex load paths on a building.

Once we established that model, we could then test the removal of some or all of the external loadbearing envelope to mimic the aircraft crash. One of the more obvious problems is that this will result in redistribution of the envelope load over the zone towards the corner sections, which may increase the localised loads beyond the capcaity of the surviving members and hence contribute to failure.

The next issue is whether four to six floor slabs, each comprising somewhere between 100 and 125mm of reinforced concrete together with steel permanent formwork and the structural supports would have sufficient energy to cause the next lowest intact floor to collapse. Floors aren't designed to take this kind of dynamic impact load, so we'd have to get an engineer to model the truss-end connections (the weak point) and determine whether they would shear. If they did, we could be facing a self-sustaining process.

So the problem is not that I don't want to answer the question, but rather that we would only know if we ran a series of detailed structural analyses.

ETA: We would also have to look at whether the central core structure was adequately restrained in the absence of the floor slabs, although I am less concerned about this causing immediate failure - the structure could stand for short lengths on its own per construction photographs, although it must be borne in mind that it was obviously not fully loaded at that point.

[gumboot]

Point me in the direction of that, please; a (so far) polite young chap at LCF is questioning me on it and I explained that one would have to fully model it to know. Obviously I don't want to waste his time if someone has done it already.


Well the collapse on 9/11 involved 4 or 5 floors essentially being removed from the equation at once (collapse initiation was across the entire aircraft impact zone, not just one floor) and NIST said in their report that global collapse resulted because the lower structure had insufficient strength to stop the failing mass of the upper floors.

-Gumboot

[gumboot]

I disagree, but am more than happy to be corrected. These were my thoughts on the issue at LCF, albeit that I was given a hypothetical scenario of between four and six floors being removed.


When I say "one floor" removed I mean the entire floor - including the truss, core columns, and exterior columns. Sorry, I didn't make that too clear.

-Gumboot

[Architect]

Well the collapse on 9/11 involved 4 or 5 floors essentially being removed from the equation at once (collapse initiation was across the entire aircraft impact zone, not just one floor) and NIST said in their report that global collapse resulted because the lower structure had insufficient strength to stop the failing mass of the upper floors.

With respect, that's not my understanding; sagging of floors due to damage and fire leads to buckling of outer loadbearing envelope; loads are redistributed through the facade and, via the hat trusses, to the core however these exceed loadbearing capacity and failure occurs.


When I say "one floor" removed I mean the entire floor - including the truss, core columns, and exterior columns. Sorry, I didn't make that too clear.


The suggestion that removing all forms of structural support might result in collapse is not hard to defend!

[coughymachine]

The suggestion that removing all forms of structural support might result in collapse is not hard to defend!
I am not so much asking, would the building collapse, as would it collapse with the same characteristics as we observed on 9/11? If not, why not?

[gumboot]

With respect, that's not my understanding; sagging of floors due to damage and fire leads to buckling of outer loadbearing envelope; loads are redistributed through the facade and, via the hat trusses, to the core however these exceed loadbearing capacity and failure occurs.


Um... yes? :confused:

How are we disagreeing?




The suggestion that removing all forms of structural support might result in collapse is not hard to defend!


No, not to people with even a basic scientific understanding. But it's something Truthers find hard to grasp.

-Gumboot

[gumboot]

I am not so much asking, would the building collapse, as would it collapse with the same characteristics as we observed on 9/11? If not, why not?



Perhaps you can specify which characteristics you're talking about?

-Gumboot

[ref]

I am not so much asking, would the building collapse, as would it collapse with the same characteristics as we observed on 9/11? If not, why not?

So, would a removal of entire structural support accross one floor result in an exact same kind of collapse, as with the buckling and exceeded load bearing capacity of the columns?

[coughymachine]

Perhaps you can specify which characteristics you're talking about?
Well, primarily, would it lead to a 'global collapse'?

[gumboot]

Well, primarily, would it lead to a 'global collapse'?

I think that's a pretty safe bet.

-Gumboot

[Architect]

Yes, the dynamic load imposed on the "intact" lower structure would almost certainly exceed its loadbearing capacity.

[einsteen]

Once the upper mass and structure of the WTC drops to the below structure the like of WTC, it will collapse. Didn't Bazant calculate, that only a drop of 0,5 meters for the upper part would have been enough to produce the result we all saw.

It is nice that Prof Bazant uses a continuous model, that implies that if the twin towers were solid the same global collapse would occur, of course after enough initial kinetic energy. Then you could apply the model also for a tree trunk. Often called a stupid example, because the buildings were 95% space (although the average density is half that of water) , but Prof Bazant proved it, if you assume energy is only absorbed in the upper part of the building (or tree) then a global collapse is possible under these assumptions. Of course they are mathematical models and no realistic physical models, but that is a different story.

[ref]

This is the Bazant paper once again for everyone to see, and the paragraph I quoted:

http://www.nistreview.org/WTC-PROGRESSIVE-COLLAPSE-BAZANT.pdf



The kinetic energy of the top part of tower impacting the floor below was found to be about 8,4x
larger than the plastic energy absorption capability of the underlying story, and considerably higher than that if fracturing were taken into account (Bazant and Zhou 2002).

This fact, along with the fact that, during the progressive collapse of underlying floors (Figs. 1d and 2) the kinetic energy rapidly increases (roughly in proportion to the square of the number of stories traversed), sufficed to Bazant and Zhou (2002) to conclude that the tower was doomed once the top part of tower has dropped through the height of one story (or even 0.5 m). It was also observed that this conclusion made any calculations of the dynamics of progressive collapse after the first single-story drop of upper part superfluous.


The relative smallness of energy absorption capability compared to the kinetic energy also sufficed to explain, without any further calculations, why the collapse duration could not have been much longer (say, twice as long or more) than the duration of a free fall from the tower top.

[einsteen]

Yeah, it is the same as Greening but in formal notation and not discrete but continuous and it is tough of course, mainly because of the setup. But the physics behind it is the same as Greening. The crush-down is Greening's first stage of collapse and the crush-up the 2nd stage of collapse.

[PhantomWolf]

It really depends on what you mean by similar. If you were standing a mile away then yes they likely would be similar, but if you were looking at the building through a camera zoomed lens, then no they wouldn't. The closest you could get it would be to blow one side causing it to tilt and then fall, but this would still cause explosions that would be obvious. There is also no way to produce the initial deforming of the prerimeter colunms which initiated the WTC collapse, you'd have to mimic it with the explosives, which would then be obvious.

I suspect that if you dropped the top of the tower by a floor so that it fell directly onto the floor below, columns on columns, then I suspect that the result would still be similar, but you'd probably see the tower budge out below the initial impact point, then rupture there, rather then what we saw with the top falling into the lower "tube" and then peeling the prerimeter columns outwards. Of course this is pure speculation on my part, so I could be totally wrong.

[qarnos]

I am not so much asking, would the building collapse, as would it collapse with the same characteristics as we observed on 9/11? If not, why not?

The building would most likely collapse top-down, like on 9/11, but you would not see any bowing of the perimeter columns prior to collapse initiation.

If your assumption that the failure of the core would cause the floor trusses to deform the perimeter columns is correct, which is dubious at best, the bowing would not be witnessed until after collapse initiation, and, I would imagine, only for a very brief moment before the perimeter columns fail and collapse.

We would also not witness any sagging floor trusses like those which are evident in at least one video I have seen.

So, to answer your question, it would appear to me (iamnotanexpertTM) that the collapse itself would appear somewhat similar to what we witnessed on 9/11, but the events leading up to the collapse would bare no resemblance at all.

ETA: Also, we would likely not witness the "half-topple" of the upper section of the tower. This would make the collapses even less similar.

[qarnos]

I suspect that if you dropped the top of the tower by a floor so that it fell directly onto the floor below, columns on columns, then I suspect that the result would still be similar, but you'd probably see the tower budge out below the initial impact point, then rupture there, rather then what we saw with the top falling into the lower "tube" and then peeling the prerimeter columns outwards. Of course this is pure speculation on my part, so I could be totally wrong.

Unless, or course, FNET = 0.

[PhantomWolf]

Unless, or course, FNET = 0.

That must be why I have trouble getting out of bed in the morning.

[Gravy]

Consider this hypothetical scenario:

A decision has been made to bring a WTC-type tower down in a controlled manner. The reasons are legitimate and irrelevant.Hi coughy. Just a comment: if a quarter-mile high building were brought down by explosives, it wouldn't come down in a "controlled manner" in the demolitions sense. Debris would fly a great distance and damage surrounding structures, the wind created by the collapse would cause additional damage to nearby buildings, and there would be the possibility of vibration and shock damage to foundations and other subterranean structures.

[boloboffin]

I don't think I'm too far away from the subject to say that a normal controlled demo of the towers would never have produced the results we saw on 9/11. It would have started from the bottom down, there would have been charges throughout the building, and the debris pile would have been much tighter. We wouldn't have seen the sides peel away to scatter perimeter column panels into the Winter Garden and other NY buildings. WTC 5 and 6 may have been demoed first to give the debris pile room. WTC 7 would still be standing. The core would have been completely dismantled in the initial blasts, instead of being left to stand and deflect debris all over.

In short, what we saw on 9/11 would not be the sane choice of anyone wishing to demolish a similar building under other circumstances. By demolishing the 80th floor, the building would most likely still fall, but many elements of the 9/11 fall would remain - the standing core, the out-of-control debris field, extensive damage to surrounding buildings, and we haven't even talked about stripping the building to eliminate underground fires and toxic fumes.

[Undesired Walrus]

http://video.google.com/videoplay?docid=-5405555553528290546

The above video clearly shows the perimeter columns of the World Trade Center bow inwards before the collapse. This was due to the sagging floor trusses pulling them inwards as they sagged further and further.

To replicate the collapse of the towers, you would somehow need to get the floor trusses to sag enough to pull those perimeter columns inward. Fire will do this, explosives and thermite will not.

Blowing all the core columns on one floor of the tower would also create a visible and audible explosion outside of the trade centers. This was not seen on 9/11.

Dont be silly. Don't you know brave NWO operatives were inside pulling the floor trusses inwards?

Silly Doc.

[aggle-rithm]

Consider this hypothetical scenario:

A decision has been made to bring a WTC-type tower down in a controlled manner. The reasons are legitimate and irrelevant.


Hold it right there. They wouldn't be legitimate, because controlled demolition by explosives is against the law in New York City. There's too much underground infrastructure that might be damaged.

[Undesired Walrus]

Hold it right there. They wouldn't be legitimate, because controlled demolition by explosives is against the law in New York City. There's too much underground infrastructure that might be damaged.

Or so you think....

[aggle-rithm]

Dont be silly. Don't you know brave NWO operatives were inside pulling the floor trusses inwards?

Silly Doc.

I'm sure glad I called in sick that day.

[Undesired Walrus]

The thing I simply don't get about the truthers is their 'contention' that the fires could have not get hot enough to cause the floor trusses to bow inwards.. so, what is their explanation to video evidence of this?

[PhantomWolf]

Hold it right there. They wouldn't be legitimate, because controlled demolition by explosives is against the law in New York City. There's too much underground infrastructure that might be damaged.

He said a WTC-type tower, not the WTC. Since this hypothetical tower isn't actually the WTC, we can put in in Las Vegas instead of New York.

[twinstead]

The thing I simply don't get about the truthers is their 'contention' that the fires could have not get hot enough to cause the floor trusses to bow inwards.. so, what is their explanation to video evidence of this?

One of our intrepid truthers insisted that it was an optical illusion. Was that Christophera?

[Newtons Bit]

That was pdoh twinstead.

[aggle-rithm]

He said a WTC-type tower, not the WTC. Since this hypothetical tower isn't actually the WTC, we can put in in Las Vegas instead of New York.

Does Las Vegas have sufficient bedrock to hold up a tower that size?

Speaking hypothetically, of course.

[aggle-rithm]

The thing I simply don't get about the truthers is their 'contention' that the fires could have not get hot enough to cause the floor trusses to bow inwards.. so, what is their explanation to video evidence of this?

More unbelievable is that so many people would jump to their deaths for no reason at all.

Hello? What would it take to make a troofer jump off a 110-story building to a certain death? Fear of SMOKE?!?

Remind me not to light a cigarette around these guys. Could get ugly.

[PhantomWolf]

Does Las Vegas have sufficient bedrock to hold up a tower that size?

Speaking hypothetically, of course.

Does it matter? We're going to hypothetically blow it up once it's hypothetically built, so as long as it doesn't hypothetically fall over before it hypothetically falls down, we're hypothetically set, hypothetically that is.

[aggle-rithm]

Does it matter? We're going to hypothetically blow it up once it's hypothetically built, so as long as it doesn't hypothetically fall over before it hypothetically falls down, we're hypothetically set, hypothetically that is.

How much hypothetical insurance do we have on it? Hypothetically?

Is it covered for hypothetical thermite damage?

[PhantomWolf]

More unbelievable is that so many people would jump to their deaths for no reason at all.

Hello? What would it take to make a troofer jump off a 110-story building to a certain death? Fear of SMOKE?!?

Remind me not to light a cigarette around these guys. Could get ugly.

No no no no, you have it wrong, they didn't jump, they were trying to get away from the smoke and fell out the window. I mean, anyone that would jump from buildings that so obvioiusly weren't on fire would have to be as stupid as pilots that couldn't take down a cave dwelling arab with a little box cutter.

[chipmunk stew]

The thing I simply don't get about the truthers is their 'contention' that the fires could have not get hot enough to cause the floor trusses to bow inwards.. so, what is their explanation to video evidence of this?
I'm pretty sure this is where the thermite is supposed to have come in.

edit: ...hypothetically.

[JonnyFive]

How much hypothetical insurance do we have on it? Hypothetically?

Is it covered for hypothetical thermite damage?

Since you are hypothetically telling us that you are hypothetically blowing it up, any hypothetical insurance company wouldn't give you the hypothetical time of day, much less issue any hypothetical coverage on the hypothetical building. ;)

If I were the hypothetical underwriter writing the hypothetical proposal, I would hypothetically decline and laugh in your hypothetical face.

You might want some hypothetical general liability for the hypothetical demolition workers, though.

[Undesired Walrus]

I'm pretty sure this is where the thermite is supposed to have come in.

edit: ...hypothetically.

And thermate that can burn a hole in steel was meant to be able to warp and displace floor trusses?

[JimBenArm]

If all you youngsters had worn your sweaters like I told you to, you wouldn't have gotten hypothermia!

[flameowl]

Well, someone else has pointed out that it's not really a controlled demolition if a 110 story structure is demolished with explosives, so I'll just add my questions on to that:

What's the difference in cost of demolishing the building in the conventional way (painstakingly taking it apart from the top down, recycling all the materials that you can and binning the rest)? Is the conventional method any more/less expensive? With the time-frame needed to wire even a small building for explosive demolition, does it really save any time (I watched a building (probably 30 stories) in Toronto be disassembled from the top down over the course of 4 months this winter, would wiring, demolishing and clearing the site have taken longer)? What about those recyclable materials, if they are deconstructed properly are they more or less valuable than what can be scavenged from the rubble pile that is left at the end of an explosive demolition? Is there an increased level of pay for workers on an explosive demolition site (insurance costs/danger pay) that would have to be taken into account?

Without answers to those questions, I don't think that anyone can say that "obviously" explosive demolition of the buildings were the cheaper, easier way to go. I think that an argument could be made that with the wealth of materials in the towers and the extra risks (sure, in the CT scenario insurance doesn't need to be paid, but I'm thinking danger pay/hush money would make up for that expense) would be worth taking them down in the conventional manner if they did need to come down (which has not been shown).

[chipmunk stew]

And thermate that can burn a hole in steel was meant to be able to warp and displace floor trusses?
Hey man, I'm just repeating what I read on a website. They said they were peer reviewed. What, did you expect me to do? Fact-check?!? Fack-checking is for nerds, nerd.

[JonnyFive]

Hey man, I'm just repeating what I read on a website. They said they were peer reviewed. What, did you expect me to do? Fact-check?!? Fack-checking is for nerds, nerd.

As the great 28th Kingdom once said: "Right brained = nerdness"

I'm not sure precisely what the hell he was talking about, but I think we've got some seriously right brained, nerdny people in here*. :)




*Including me.

[R.Mackey]

If you blow one floor, below say Floor 100, then yes, a WTC Tower replica would collapse. This is what Dr. Bazant shows. However, you would get none of the other phenomena seen on Sept. 11th as others have noted, including the bowing perimeter, sag in the upper structure, leaning, rotation, the "kink" seen in the upper block, sagging floors near impact, etc.

Destroying a WTC Tower in this fashion would almost surely not be cheaper than a less dramatic form of disassembly, simply because the collapses destroyed numerous other buildings nearby. This is the kind of thing we like to avoid.

A truly controlled demolition, i.e. emptying and weakening of the structure followed by minimum-charge explosives on virtually every floor, might be cheaper than a more gradual demolition -- this is hard to say -- but it would be by far the most complex explosive demolition in history, and there are legal problems that might prove insurmountable.

[e^n]

I'm convinced with significant basement work involving basically emptying it out combined with removing a significant amount of floor trusses and some hat truss reconfiguration you could get the entire towers to fall in on themselves.

Of course it's way beyond feasible but damnit it would work and no damned scientist is going to tell me otherwise.

[Apollo20]

I think the most interesting aspect of Coughymachine's question is that he/she wants to bring the towers down with explosives ON ONE FLOOR.

This is important because most Demolitionists assume/propose that there were explosives on MANY FLOORS. (Hence all the squibs stuff, etc, etc.).

The point is that a controlled demolition, once initiated, is a gravity driven collapse. I believe that explosives ON ONE FLOOR would certainly have brought down the towers.

But if you believe Gordon Ross, he would argue that explosives ON ONE FLOOR would be INSUFFICIENT to bring down the towers!

[Architect]

Just one of Gordon's many errors, I'm sure.

[beachnut]

Consider this hypothetical scenario:

A decision has been made to bring a WTC-type tower down in a controlled manner. The reasons are legitimate and irrelevant.

Time is taken to prepare the building in the proper way and the site is evacuated in advance.

If all of the core columns were blown simultaneously on one floor - say the 80th - would the building collapse as the towers did on 9/11?

If the collapse mechanism couldn't be replicated by the simultaneous removal of the core columns at one floor, could it be replicated by simultaneously removing the core columns at two floors? If not, how many?

If the collapse mechnism couldn't be replicated, why not?

I started having a similar conversation with one of your members in another forum but, unfortunately, that ended before I got to grips with his line of reasoning.
I was watching a video of the WTC fail. The section 2 or 3 floors above the initial impact seem to start down first and then the whole area impacted the lower section driving out flames and smoke. To a truther this is the explosives going off, but I have never seen explosives so slow without the sound. Point being, the upper section had a chance to build up KE, possible falling more than a floor before impacting the lower section of the WTC.

To blow up one section you need to study the collapse or look at some of the studies out now. I think there may be enough energy if you have enough mass to begin global collapse when your top section falls one floor to the lower section. Most of the studies I believe were conservative, not like my visual take above, and they only used one floor to calculate the initiation of the failure. Thus dropping the top floors one floor are enough to start a chain reaction of destruction. I would have to study the papers again, but I think some used one floor of fall, and based the KE/momentum on that. If you want a someone to tell you the building will stand see Ross's work.

[gumboot]

Anyone else suspect the woo-woos are lying up for a game of "chase-your-own-tail"?

It seems like they're planning to rework the CD theory to argue that only one floor as blown, and the rest happened as is.

The problem with this scenario (aside from the practicality of planting said explosives) is to accept it you have to automatically abandon every single argument CTers have ever raised to support CD.

First responders heard explosions? None of them reached the impact areas, and any that did didn't live to tell about it.

Looked like every floor was blown? Not any more.

Bombs in basement? Nope.

Time of collapse? It was gravity driven after the one floor was blown.

Basically they have nothing left at all.

-Gumboot

[PhantomWolf]

I was watching a video of the WTC fail. The section 2 or 3 floors above the initial impact seem to start down first and then the whole area impacted the lower section driving out flames and smoke. To a truther this is the explosives going off, but I have never seen explosives so slow without the sound.

I've never seen demolition explosions that happen after the collapse has already started.

[Firestone]

As the great 28th Kingdom once said: "Right brained = nerdness"

I'm not sure precisely what the hell he was talking about, but I think we've got some seriously right brained, nerdny people in here*. :)




*Including me.Please respect the Master's theories: left-brainers are nerds, right-brainers are ... well let Him explain how right-brainers are:Right-brain people...can look at this video:

http://www.youtube.com/watch?v=LD06SAf0p9A

Ask a few questions like...what type of building...how tall, what type of damage. 47 story, steel structured high rise, with a few scattered fires, and some exterior damage (on one side) from falling debris. We take in this basic information, watch the video a few times...and, conclude...that the building couldn't have physically collapsed the way it does from the damages reported. It doesn't take any degree in structural engineering...it just takes common sense.Real left-brainers watch the video a few times ... and conclude ... :)

[Cl1mh4224rd]

. . .the post-collapse initiation process.

:boggled: The what...?

[Mr. Skinny]

As the great 28th Kingdom once said: "Right brained = nerdness"

I'm not sure precisely what the hell he was talking about, but I think we've got some seriously right brained, nerdny people in here*. :)




*Including me.


At the risk of earning a Stundie along the way, I must admit, quite honestly, that I can never tell which side of my brain is working on a problem. Is one side of your head supposed to tingle when you think about something? :D

I'm an engineer, so I know I deserve a nerd tag somehow, but, as a nerd, I need to know which side of my brain I'm using. What if I'm listening to music, or looking at a piece of art? Do I use the same side of my brain that I use when I'm determining what volume of hydrogen must occupy a space before the atmosphere has reached it's lower explosive limit?

Inquiring minds, etc....

[Mr. Skinny]

:boggled: The what...?
The post-collapse initiation process is when rescue workers started looking for bodies, I think.

[Newtons Bit]

I'm convinced with significant basement work involving basically emptying it out combined with removing a significant amount of floor trusses and some hat truss reconfiguration you could get the entire towers to fall in on themselves.

Of course it's way beyond feasible but damnit it would work and no damned scientist is going to tell me otherwise.

It could probably be done with a VERY large amount of planning involved. But if the wind blows the wrong way or you set a charge wrong, and the whole thing is going to come down on everyone's head. Controlled Demolition isn't done on very large buildings for a very specific reason: the small, the not insignifcant chance that something goes wrong and damages buildings/life around it is too expensive to insure.

The cost to infastructure around the WTC was what, 500 billion? Yes, I'm pulling that number out of my "filing cabinet", however suppose the insurance company that was going to bond the contractor for demolition of the building estimated that there was a 99% chance that nothing would go wrong. That's a 1% chance that something will, or 5billion dollars in risk. Can you imagine what your premiums on that would be?

[PhantomWolf]

The post-collapse initiation process is when rescue workers started looking for bodies, I think.

You know, even nearly 6 years on, that still seems just a little inappropriate.

[Cl1mh4224rd]

The post-collapse initiation process is when rescue workers started looking for bodies, I think.
But that's not the context...

The point is that he wonders if you could reprocude the collapse by blowing up the columns of one story (core and maybe even the perimeter columns), he is interested in the post-collapse initiation process.

The official story indeed says: yes

[CHF]

The point is that a controlled demolition, once initiated, is a gravity driven collapse. I believe that explosives ON ONE FLOOR would certainly have brought down the towers.

But if you believe Gordon Ross, he would argue that explosives ON ONE FLOOR would be INSUFFICIENT to bring down the towers!

Just shows how absurd the twoofers are being with this whole issue.

The simplest demolition theory would indeed have charges on one floor initiating the collapse. (Granted that theory is still a bit silly since it assumes the charges would survive the jet impact and fires).

Instead what do they generally go with?

Charges on almost every floor! Enough explosives to blast all the concrete into dust! And create rivers of molten steel!

[Gravy]

(snip)

Without answers to those questions, I don't think that anyone can say that "obviously" explosive demolition of the buildings were the cheaper, easier way to go. I think that an argument could be made that with the wealth of materials in the towers and the extra risks (sure, in the CT scenario insurance doesn't need to be paid, but I'm thinking danger pay/hush money would make up for that expense) would be worth taking them down in the conventional manner if they did need to come down (which has not been shown).The short answer is that yes, in most cases where CD is an option, it would be less expensive (and much safer) than demolition by hand, because a relatively small work crew is needed and gravity does most of the work of reducing the building to pieces that can be hauled away. I doubt if there are many people who would choose the CD option if it were more expensive than traditional demolition.

Of course, the "less expensive" CT argument is based on the fallacy that the buildings were losing money and falling apart, which is silly.

[PhantomWolf]

Just shows how absurd the twoofers are being with this whole issue.

The simplest demolition theory would indeed have charges on one floor initiating the collapse. (Granted that theory is still a bit silly since it assumes the charges would survive the jet impact and fires).

Instead what do they generally go with?

Charges on almost every floor! Enough explosives to blast all the concrete into dust! And create rivers of molten steel!

And this just in. New documents show that the WTC was actually built using C4 and thermite, not concrete and steel and the US Government claims...

[Dave Rogers]

The simplest demolition theory would indeed have charges on one floor initiating the collapse. (Granted that theory is still a bit silly since it assumes the charges would survive the jet impact and fires).

Instead what do they generally go with?

Charges on almost every floor! Enough explosives to blast all the concrete into dust! And create rivers of molten steel!

Ah, but the charges on multiple floors are needed to explain the fact that the collapse initiated in the collision zone, and since an experienced airline pilot couldn't even hit the Pentagon on a simulator then the Impossibly Vast Conspiracy wouldn't know where their remote controlled nonexistent planes would hit the tower with their thermite-loaded explosive missiles, so there have to be charges on every floor so the collapse can start in the right place and they have to be embedded in the concrete so that the dust can make all the rescue workers ill because, er...

I have to go and lie down, my brain hurts.

Dave

[coughymachine]

Thanks to all who contributed. Sorry I went down-periscope - I had to attend a customer meeting and, frankly, didn't expect such a swift and voluminous response.

I guess the conclusion is that the removal of the core columns at one floor (or else a very small number of floors) would lead to the 'global collapse' of a WTC1-type structure.

Appreciate your time.

[einsteen]

I guess the conclusion is that the removal of the core columns at one floor (or else a very small number of floors) would lead to the 'global collapse' of a WTC1-type structure.


That is an implication of the official story. Then you have to accept that solid structures with a density of 300 kg/m^3 (or a solid structure with a density only dependent on the y-axis) and a similar strength as the wtc will also collapse if you drop the upper block a little bit.

[e^n]

That is an implication of the official story. Then you have to accept that solid structures with a density of 300 kg/m^3 (or a solid structure with a density only dependent on the y-axis) and a similar strength as the wtc will also collapse if you drop the upper block a little bit.

In what way does any paper imply this? I asked this over at LC but I don't know if you've responded to it.

[Gravy]

That is an implication of the official story. Then you have to accept that solid structures with a density of 300 kg/m^3 (or a solid structure with a density only dependent on the y-axis) and a similar strength as the wtc will also collapse if you drop the upper block a little bit.No, you have to accept that building components break when they're overstressed.

[Belz...]

Anyone else suspect the woo-woos are lying up for a game of "chase-your-own-tail"?

It seems like they're planning to rework the CD theory to argue that only one floor as blown, and the rest happened as is.

The problem with this scenario (aside from the practicality of planting said explosives) is to accept it you have to automatically abandon every single argument CTers have ever raised to support CD.

First responders heard explosions? None of them reached the impact areas, and any that did didn't live to tell about it.

Looked like every floor was blown? Not any more.

Bombs in basement? Nope.

Time of collapse? It was gravity driven after the one floor was blown.

Basically they have nothing left at all.

-Gumboot

Well, the advantage of basing your theories of fantasy is that you can warp it to any shape you wish, at any time. They'll work it out.

[Belz...]

That is an implication of the official story. Then you have to accept that solid structures with a density of 300 kg/m^3 (or a solid structure with a density only dependent on the y-axis) and a similar strength as the wtc will also collapse if you drop the upper block a little bit.

Do you have a condition that prevents you from forming long-term memories ?

[Dave Rogers]

Then you have to accept that solid structures with a density of 300 kg/m^3 (or a solid structure with a density only dependent on the y-axis) and a similar strength as the wtc will also collapse if you drop the upper block a little bit.

Made out of those well-known structural materials of around 300 kg/m^3 density, such as ground alfalfa, wood bark, bran, shredded coconut, cork, rolled oats or tobacco, no doubt. I'd call your argument a strawman, but I don't think straw is dense enough.

Dave

[einsteen]

In Bazant's paper they use in fact Greening's model but in a continuous model because then you can set up your differential equations. Since in such a model you have no breaking columns etc they use a kind of energy equivalent model. The only thing I wanted to say is that it is possible to prove a global collapse with a continous model. That's what they do as far as I can understand with my lay man's view. No I don't think a solid object would collapse in the wtc manner but of course they only want to calculate the velocity, collapse time etc and their model is valid because the energy picture is valid, it is a kind of approach for the real situation. But I think Lozenge124's question in the other thread still stands and that is the question of the E1 collapse model.

[coughymachine]

Well, the advantage of basing your theories of fantasy is that you can warp it to any shape you wish, at any time. They'll work it out.
Dare I ask what a 'woo-woo' is?

I assume gumboot thinks I am one and that you concur.

[chipmunk stew]

Made out of those well-known structural materials of around 300 kg/m^3 density, such as ground alfalfa, wood bark, bran, shredded coconut, cork, rolled oats or tobacco, no doubt. I'd call your argument a strawman, but I don't think straw is dense enough.

Dave
:dl:

Well Judy Wood did mention Wheat Chex at some point...

[einsteen]

You mean Judy "elastic collisions" Wood

btw. here is Bazant's solid mass collapse model

http://i10.tinypic.com/5xg3i9h.gif

A little bit a crappy picture for such a professional paper.

[aggle-rithm]

Dare I ask what a 'woo-woo' is?


It's the opposite of a skeptic. Someone who believes something because it's really, really cool, not because there is evidence to support the belief.

[aggle-rithm]

:dl:

Well Judy Wood did mention Wheat Chex at some point...

And the Keebler elves. What is it with her and food products? Does she have an eating disorder?

[coughymachine]

It's the opposite of a skeptic. Someone who believes something because it's really, really cool, not because there is evidence to support the belief.
Thanks. I have been reading through some of the other threads and saw that 'woo-woo' was a very, very clever corruption of the word 'truther'.

[aggle-rithm]

Thanks. I have been reading through some of the other threads and saw that 'woo-woo' was a very, very clever corruption of the word 'truther'.

No, we use "troofer" or "twoofer" to be more specific. "Woo-woo" more frequently refers to people who believe in magic powers. Troofers are merely a small subset.

[defaultdotxbe]

Thanks. I have been reading through some of the other threads and saw that 'woo-woo' was a very, very clever corruption of the word 'truther'.
actually it predates 9/11 truth and was coined to refer to psychics or similar persons (and still does in the parts of the forum where those things are discussed)

[coughymachine]

No, we use "troofer" or "twoofer" to be more specific. "Woo-woo" more frequently refers to people who believe in magic powers. Troofers are merely a small subset.
Thanks. I just wanted to know how I was being labelled.

[aggle-rithm]

Thanks. I just wanted to know how I was being labelled.

I don't think anyone's labeling you yet, but we do know a pattern when we see one. Do you have any idea how many people come in here in the guise of objectivity, just asking innocent questions, only to reveal themselves as being radical, closed-minded conspiracy theorists?

That may be you and it may not be. Time will tell. But you do fit the pattern.

[NobbyNobbs]

I think it's certainly true that the consensus view is a total failure of one floor would result in a global collapse much like we saw on 9/11.


This is the point I wanted to clarify.


Forgive me for not reading this whole thread, but when I got this far, skepticism gave way to cynicism. Gumboot and others gave a lengthy explanation of their viewpoints, and Coughy has taken this one sentence out of it. I forsee him parading this one sentence around, saying "See? Even the Skeptics admit it's possible!"

I apologize profusely if I have jumped the gun. The number of trolls coming on here and asking "just wondering" questions has become dramatic.

[coughymachine]

I don't think anyone's labeling you yet, but we do know a pattern when we see one. Do you have any idea how many people come in here in the guise of objectivity, just asking innocent questions, only to reveal themselves as being radical, closed-minded conspiracy theorists?

That may be you and it may not be. Time will tell. But you do fit the pattern.
This seems typical of the sort of closed-mindedness you're (nearly) accusing me of.

The irony is, I actually joined this forum to get your suggestions on a de-bunking I was attempting elsewhere. But, due to newbie link restrictions, I couldn't.

[coughymachine]

The number of trolls coming on here and asking "just wondering" questions has become dramatic.
What is actually wrong with asking 'just wondering' questions?

[ref]

I don't think anyone's labeling you yet, but we do know a pattern when we see one. Do you have any idea how many people come in here in the guise of objectivity, just asking innocent questions

I did that.

only to reveal themselves as being radical, closed-minded conspiracy theorists?

I don't think I did that :p


Welcome coughymachine. Actions determine the outcome.

[defaultdotxbe]

What is actually wrong with asking 'just wondering' questions?
nothing, but the vast majority of people that come here "just wondering" actually arent, and have already formed strong opinions and just playing games

for example a few weeks ago we had someone claim he was "just introduced" to moon landing hoax conspiracies, but over the course of about 20 posts it became clear he was very familiar with the idea and certainly had not just found out about it

[Disbelief]

What is actually wrong with asking 'just wondering' questions?

Because so often, it has been a front for troofer "theories." I have only been here a few months and I have seen it many times with both new posters and various socks.

[Disbelief]

In Bazant's paper they use in fact Greening's model but in a continuous model because then you can set up your differential equations. Since in such a model you have no breaking columns etc they use a kind of energy equivalent model. The only thing I wanted to say is that it is possible to prove a global collapse with a continous model. That's what they do as far as I can understand with my lay man's view. No I don't think a solid object would collapse in the wtc manner but of course they only want to calculate the velocity, collapse time etc and their model is valid because the energy picture is valid, it is a kind of approach for the real situation. But I think Lozenge124's question in the other thread still stands and that is the question of the E1 collapse model.

Why don't you just PM Greening? I have sent him a couple of questions and he was very kind to respond.

[babazaroni]

What is actually wrong with asking 'just wondering' questions?

Because the questions are all one sided.

For instance, we never hear the 'just asking questions' people ask a question like this:

Why do people(Rosie for instance) claim the towers collapse in 9 seconds but the videos obviously show 15+ second collapses?

Also, these people don't respond to the answers, but just move on to another question. You don't hear things like, 'OK, I had not thought about it like that, thanks'.

[firecoins]

I am just wondering why do people claim the tower's collapse in 9 seconds but the videos obviously show 15+ second collapses?:D

To Coughymachine: You are obviously not the first guy to come to this site ask questions. We don't "defend" the "official" version. We defend what we have found out from hard facts and hard evidence. The evidence so far proves the "official" version. This evidence was not handed on down from the government but comes from many sources as well as logicical deduction. Most conspiracy theories are illogocal, not well thought out and have little or no evidence to back them up. From no plane theories to space beams, many are just plain ridiculous. Even the most plausible theoires have major flaws in them.

[coughymachine]

nothing, but the vast majority of people that come here "just wondering" actually arent, and have already formed strong opinions and just playing games
Well, for the record, if I ask a 'just wondering' question, it's because I'm 'just wondering' - in other words, I really want to know.

If I have an opinion, I'll offer it. But this won't stop me asking questions to explore other people's opinions.

[coughymachine]

The above video clearly shows the perimeter columns of the World Trade Center bow inwards before the collapse. This was due to the sagging floor trusses pulling them inwards as they sagged further and further.
I apologise in advance for the crude graphics - MS Paint is about as sophisticated as I get.

Wouldn't the removal of the core columns, and the resulting drop in the core, cause the perimeter columns to bend in the same way?

http://i148.photobucket.com/albums/s32/coughymachine/WTCbendingperimetercolumns.jpg

[babazaroni]

I apologise in advance for the crude graphics - MS Paint is about as sophisticated as I get.

Wouldn't the removal of the core columns, and the resulting drop in the core, cause the perimeter columns to bend in the same way?

http://i148.photobucket.com/albums/s32/coughymachine/WTCbendingperimetercolumns.jpg

No, the damage to the building was asymmetric. The building adjusted (tilted slightly) when perimeter columns and core columns were damaged by the initial impact.

[aggle-rithm]

I apologise in advance for the crude graphics - MS Paint is about as sophisticated as I get.

Wouldn't the removal of the core columns, and the resulting drop in the core, cause the perimeter columns to bend in the same way?

http://i148.photobucket.com/albums/s32/coughymachine/WTCbendingperimetercolumns.jpg

Funny you should mention this, because something very similar happened in New York a few years back...seems some airliners crashed into a couple of skyscrapers and structural failure due to the impact and the fires caused them to collapse in a manner very similar to this.

If, hypothetically speaking, someone wanted to accomplish something like this by removing the core columns by some other means (I don't know, explosives, maybe?) then it would be advisable for them not to crash airliners into the same area where they were planning on removing the columns. It would make the area very difficult to access, and any pre-placed equipment would most likely be damaged or destroyed.

[beachnut]

That is an implication of the official story. Then you have to accept that solid structures with a density of 300 kg/m^3 (or a solid structure with a density only dependent on the y-axis) and a similar strength as the wtc will also collapse if you drop the upper block a little bit.
It is not some implication of an official story; it is physics, structures, engineering, knowledge, facts, evidence, and critical thinking. All opposites of the truth movement cult junk of hand waving and ranting about questions and making up lies.

[defaultdotxbe]

I apologise in advance for the crude graphics - MS Paint is about as sophisticated as I get.

Wouldn't the removal of the core columns, and the resulting drop in the core, cause the perimeter columns to bend in the same way?

http://i148.photobucket.com/albums/s32/coughymachine/WTCbendingperimetercolumns.jpg
in your scenario i would expect it to look more like this:

http://img.photobucket.com/albums/v190/defaultdotxbe/WTCfailingperimetercolumns.jpg

as the gravity load is transferred to the perimeter collumns via the hat truss, they are overloaded and fail

[coughymachine]

No, the damage to the building was asymmetric. The building adjusted (tilted slightly) when perimeter columns and core columns were damaged by the initial impact.
I'm not referring specifically to either WTC building, but to the scenario in the OP. In that scenario, there is no prior damage. We're simply talking about a blast to knock out the core columns in one (or more) floors.

[chipmunk stew]

This seems typical of the sort of closed-mindedness you're (nearly) accusing me of.

The irony is, I actually joined this forum to get your suggestions on a de-bunking I was attempting elsewhere. But, due to newbie link restrictions, I couldn't.
The sad fact of the matter is, you're an exception. Welcome to the forums! :w2:

I hope you don't get discouraged. If you stick around for a while, it will become clear that your questions are genuine.

[babazaroni]

I'm not referring specifically to either WTC building, but to the scenario in the OP. In that scenario, there is no prior damage. We're simply talking about a blast to knock out the core columns in one (or more) floors.

Yes, then. All things being equal, then the entire collapse will be symmetric, including the start.

You should tell us why you are wondering about situations like this.

[coughymachine]

in your scenario i would expect it to look more like this:

http://img.photobucket.com/albums/v190/defaultdotxbe/WTCfailingperimetercolumns.jpg

as the gravity load is transferred to the perimeter collumns via the hat truss, they are overloaded and fail
Wouldn't the failure drag the permeter columns in though, because of the trusses?

[JonnyFive]

Please respect the Master's theories: left-brainers are nerds, right-brainers are ...

Oh, god damn. I forgot that it was right-brained = coolness, left-brained = nerdness.

I should've searched it to be sure. How many threads have the words "nerdness" in them?

[chipmunk stew]

I apologise in advance for the crude graphics - MS Paint is about as sophisticated as I get.

Wouldn't the removal of the core columns, and the resulting drop in the core, cause the perimeter columns to bend in the same way?

http://i148.photobucket.com/albums/s32/coughymachine/WTCbendingperimetercolumns.jpg
While others are much better qualified to speculate on complex, dynamic systems than I, I would expect that since your model assumes that the remaining steel retains its full strength and stiffness, the collapse would begin before any visible bending occurred, since the failure would be more sudden.

[defaultdotxbe]

Wouldn't the failure drag the permeter columns in though, because of the trusses?
possibly, i would think it could go either way, like putting pressure on a straw, you dont know what way its going to bed

either way, the bending of the perimeter collumns is visible in pictures and video well before the collapse, indicating a slow deformation, explosives tend to deform things quickly rather than slowly :)

[coughymachine]

Yes, then. All things being equal, then the entire collapse will be symmetric, including the start.

You should tell us why you are wondering about situations like this.
Happily, though I'm not sure my 'reasons' have any bearing on the answers.

I don't understand the collapse of either WTC1, WTC2 or WTC7. I am not an engineer and would be wasting my time trying to read the technical aspects of NIST's report. I have seen a lot of explanations from both sides of the debate and want to know what's possible and what's not.

In this specific scenario, I want to know whether a building, such as WTC1 could be brought down in much the same way WTC1 came down, by simultaneously blowing the core columns at one (or more) floors.

Where I go from there, I don't know.

[aggle-rithm]

in your scenario i would expect it to look more like this:

http://img.photobucket.com/albums/v190/defaultdotxbe/WTCfailingperimetercolumns.jpg

as the gravity load is transferred to the perimeter collumns via the hat truss, they are overloaded and fail

True...if the core columns on those floors were taken out completely, then there would be nothing attaching the floor trusses to the outer columns, and no reason why they should sag. Floor trusses above and below the missing column sections would be undamaged, and so would probably retain their shape until the upper section hit the lower section -- the upper section would essentially be in free-fall, and the lower section would have a normal load until impact, so why would that cause the floor trusses to sag?

[aggle-rithm]

In what way does any paper imply this? I asked this over at LC but I don't know if you've responded to it.

Sorry, LC only accepts questions with a hidden agenda.

;)

[defaultdotxbe]

In this specific scenario, I want to know whether a building, such as WTC1 could be brought down in much the same way WTC1 came down, by simultaneously blowing the core columns at one (or more) floors.

Where I go from there, I don't know.
i would think you could replicate the collapse equence itself by blowing the perimeter collumns (rather than the core) however this wouldnot replicte the symptoms leading up to the collapse, such as the internal bowing of the collumns

as chipmunk stew pointed out any bowing caused by your model would happen much too fast to be noticed as once the core (or perimeter) is removed the collapse would begin immediately, on 9/11 the bowing was visible in the minutes leading up to the collapse

[chipmunk stew]

Happily, though I'm not sure my 'reasons' have any bearing on the answers.

I don't understand the collapse of either WTC1, WTC2 or WTC7. I am not an engineer and would be wasting my time trying to read the technical aspects of NIST's report. I have seen a lot of explanations from both sides of the debate and want to know what's possible and what's not.

In this specific scenario, I want to know whether a building, such as WTC1 could be brought down in much the same way WTC1 came down, by simultaneously blowing the core columns at one (or more) floors.

Where I go from there, I don't know.
Unless the core was somehow dropping very slowly at first (this is not what was observed though) then the inward bending of the perimeter columns, which gradually bent over a period of time, could not be attributed to the dropping of the core.

I don't see how you'd be able to link the two and still produce the key observations seen in WTC1.

[Dave Rogers]

Wouldn't the failure drag the permeter columns in though, because of the trusses?

No, I don't think so. In your picture where you're showing the trusses pulling the perimeter columns in, your truss connects the core columns above the point of collapse to the perimeter columns below the point of collapse. That isn't a realistic depiction of the situation you'd expect, because there's no compression of the perimeter columns at this height to cause a failure. As the core columns are removed, the load will be transferred outwards to the perimeter columns by the floor trusses, and the perimeter columns will be pulled down at this point, so the compression and hence the failure point should be below the floor truss immediately above the point where the core columns are severed. By the same argument, the failure point should also be above the floor truss immediately below the point where the core columns are severed. The failure in the perimeter columns therefore should occur at the same height as the severing of the core columns, so there is no level at which the trusses connect between the stationary and the falling part of the building.

Usual disclaimer applies; if Newtons Bit says I'm wrong, then I strongly suspect I am.

Dave

[babazaroni]

Happily, though I'm not sure my 'reasons' have any bearing on the answers.


I do believe you are sincere. It is very rare in people who are just asking questions.

We've been led down a long path of questions before, then the trap is closed with some semantic twist at the end.

[coughymachine]

True...if the core columns on those floors were taken out completely, then there would be nothing attaching the floor trusses to the outer columns, and no reason why they should sag. Floor trusses above and below the missing column sections would be undamaged, and so would probably retain their shape until the upper section hit the lower section -- the upper section would essentially be in free-fall, and the lower section would have a normal load until impact, so why would that cause the floor trusses to sag?
The image I have is that the core gets taken out, say on one floor. The first part of the building to 'fail' is the core. Everything above the 'failure' drops, beginning with the core. However, the trusses above the 'failure' are still attached to both the core and the perimeter. When the core falls, the truss end attached to it also falls. Since the other end is still attached to the perimeter, which doesn't fall immediately, wouldn't the perimeter columns be pulled in?

[babazaroni]

The image I have is that the core gets taken out, say on one floor. The first part of the building to 'fail' is the core. Everything above the 'failure' drops, beginning with the core. However, the trusses above the 'failure' are still attached to both the core and the perimeter. When the core falls, the truss end attached to it also falls. Since the other end is still attached to the perimeter, which doesn't fall immediately, wouldn't the perimeter columns be pulled in?

There is a hat truss at the top of the building which will transfer the load the core was carrying to the perimeter columns. I'm sure something will break(like the hat truss itself) so as to not make things simple though.

[coughymachine]

No, I don't think so. In your picture where you're showing the trusses pulling the perimeter columns in, your truss connects the core columns above the point of collapse to the perimeter columns below the point of collapse.
Only because the core has 'sunk'.

[Architect]

The image I have is that the core gets taken out, say on one floor. The first part of the building to 'fail' is the core. Everything above the 'failure' drops, beginning with the core. However, the trusses above the 'failure' are still attached to both the core and the perimeter. When the core falls, the truss end attached to it also falls. Since the other end is still attached to the perimeter, which doesn't fall immediately, wouldn't the perimeter columns be pulled in?

Perhaps, but if the core begins to move then what we would see would be the deformation over a much, much wider area rather than the slower process which actually occurred.

[coughymachine]

Perhaps, but if the core begins to move then what we would see would be the deformation over a much, much wider area rather than the slower process which actually occurred.
Okay, but to seperate my scenario from 9/11 again...

Is the consensus that the removal of the core columns at one floor would lead to a 'global collapse', which could begin with the perimeter columns bending in at the point of initiation?

[einsteen]

Okay, but to seperate my scenario from 9/11 again...

Is the consensus that the removal of the core columns at one floor would lead to a 'global collapse', which could begin with the perimeter columns bending in at the point of initiation?

That depends, if it takes an hour for the bending then not, if takes a second then ok.

[babazaroni]

Okay, but to seperate my scenario from 9/11 again...

Is the consensus that the removal of the core columns at one floor would lead to a 'global collapse', which could begin with the perimeter columns bending in at the point of initiation?

The floor truss connections could shear first as they are now being stressed in a different direction then designed for.

Again, ideally, the hat truss at the top of the building will transfer the load of the core to the perimeter columns. That means the core will not drop, but be supported by the perimeter columns. However, something will probably break like the hat truss or the perimeter columns buckling.

[Dave Rogers]

Only because the core has 'sunk'.

No, because in your picture the core appears to have sunk relative to the attachment point to it of the floor trusses. If the perimeter columns fail at the same level as the core is blown, then there aren't any trusses pulling down and in on any part of the perimeter, so there isn't any major inward collapse.

Dave

[e^n]

Okay, but to seperate my scenario from 9/11 again...

Is the consensus that the removal of the core columns at one floor would lead to a 'global collapse', which could begin with the perimeter columns bending in at the point of initiation?

I'll try and answer this as thoroughly as possible as you have said you don't understand NISTs stated method of collapse either.

Your scenario:
Your scenario posits an immediate and thorough removal of the core structure at one level, we will assume that this removes the entire core structure and disconnects the floor trusses from the relevant section.

In this situation the core structure would immediately start exerting massive gravity loads on the hat truss and perimeter columns. Assuming no upper level failure of the hat truss or perimeter column structure I would imagine the lower structure damage would take place in this manner.

The floor system would either crack and buckle or remain relatively intact, in either scenario because there is no core anchoring the trusses would simply drop to the floor below. This would reduce the lateral stability of the perimeter columns at that level and combined with massive increase in load caused by the core being supported would result in rapid buckling of exterior panels over 2-5 stories at the exterior.

The result, assuming the core, hat truss and perimeter columns are strong enough to survive the initial loading would be a simultaneous symmetrical (or near enough) failure of the perimeter columns at the core removal level.

The more likely result would be a total failure of the hat truss and a gradual deterioration of the load bearing elements in the upper structure. In any case you certainly couldn't replicate the actual events of the day with this method because the inward bowing was noticed over a period of time. The only bowing you would get in your scenario would be rapid buckling of a single exterior panel height.

NISTs scenario
NISTs collapse mechanism is significantly more complex but I will attempt to summarise it.

The initial plane impacts severed up to 2/3 of the columns on one particular face, the external structure worked to redistribute loads around this opening. The plane impacts also removed fireproofing from trusses, core and exterior columns. The fires caused by the initial fuel load and explosion moved around but eventually in both towers heated a section of long span trusses to such a level they sagged by up to 42". There were also several sections of floor which disconnected from the exterior columns by means of bolt failure.

It's important not to forget the core, I was unaware of this until recently but NISTs estimation of core movement indicates that it was also sagging from the heat to a maximum extent of about 12" in sections (I believe, not entirely sure on that point).

Regardless, the bowing is visible on several photographs for a fair while before collapse and the actual collapse initiation on the south tower is visible on video. The combination of column pull-in from truss sagging and the core's weakning and sagging led to collapse initiation. I am not sure if what I am about to say is supported by NIST but in my estimation the asymmetrical loading caused by floor truss sagging and massive perimeter column damage likely caused the wide flange columns at that level to buckle / fail at their splices which is what allowed the relatively rapid initial drop.

Recreating the actual collapses via explosives would be ludicrously hard and while the general 'global collapse' is possible, the fine details would be absolutely impossible to do. The whole system is so complex it's hard to understand how it can be artificial.

[coughymachine]

No, because in your picture the core appears to have sunk relative to the attachment point to it of the floor trusses. If the perimeter columns fail at the same level as the core is blown, then there aren't any trusses pulling down and in on any part of the perimeter, so there isn't any major inward collapse.

Dave
My suggestion was not that the perimeter columns fail or are blown at the same time. The failure of the perimeter columns in my diagram is brought about by the sinking core dragging the truss with it.

[coughymachine]

I'll try and answer this as thoroughly as possible as you have said you don't understand NISTs stated method of collapse either.

I appreciate the effort you've gone to. I think I have an answer to my original question now.

[Dave Rogers]

My suggestion was not that the perimeter columns fail or are blown at the same time. The failure of the perimeter columns in my diagram is brought about by the sinking core dragging the truss with it.

Yes, but in your diagram the point of failure of the perimeter columns is above the truss that is being pulled downwards and inwards. My point is that this wouldn't be the point of failure because the compression forces on the perimeter columns would be at their greatest below this point, not above it.

Dave

[babazaroni]

My suggestion was not that the perimeter columns fail or are blown at the same time. The failure of the perimeter columns in my diagram is brought about by the sinking core dragging the truss with it.

Why do you think the core will sink relative to the perimeter columns, when there is a hat truss at the top of the building which connects them?

You know what a hat truss is right?

[chipmunk stew]

My suggestion was not that the perimeter columns fail or are blown at the same time. The failure of the perimeter columns in my diagram is brought about by the sinking core dragging the [floor] truss with it.
But assuming an intact hat truss, the perimeter columns would be under increased compression, presumably well beyond their load-bearing strength, and so the whole top section would sink with the core. The core would not sink independently.

[rwguinn]

True...if the core columns on those floors were taken out completely, then there would be nothing attaching the floor trusses to the outer columns, and no reason why they should sag. Floor trusses above and below the missing column sections would be undamaged, and so would probably retain their shape until the upper section hit the lower section -- the upper section would essentially be in free-fall, and the lower section would have a normal load until impact, so why would that cause the floor trusses to sag?

Not Quite>
If you took out the core columns, the floor above would have no center support, and would therefore sag.
This is pretty much the way I read NIST report as happening,in general, with the difference of heat effects instead of explosives weakening the core columns, damage being spread over more than 1 floor, and damage being asymetrical.

[e^n]

But assuming an intact hat truss, the perimeter columns would be under increased compression, presumably well beyond their load-bearing strength, and so the whole top section would sink with the core. The core would not sink independently.

Assuming critical hat truss failure but no exterior failure you would pretty much see the entire top section ripping itself apart as it began to sink inwards. There's no way you could get just bowing at the removal level from just removing the core. I can't think a single possible way to do it.

[coughymachine]

Why do you think the core will sink relative to the perimeter columns, when there is a hat truss at the top of the building which connects them?

You know what a hat truss is right?
Yes I do and, to a large extent, this aspect of the discussion is not related to the original question.

As I said, the fact that the removal one one floors worth of core would lead to a 'global collapse' is really all I wanted to ask.

[coughymachine]

Yes, but in your diagram the point of failure of the perimeter columns is above the truss that is being pulled downwards and inwards. My point is that this wouldn't be the point of failure because the compression forces on the perimeter columns would be at their greatest below this point, not above it.

Dave
You're right - I haven't represented that correctly.

[R.Mackey]

Dynamiting one floor would suggest an intact hat truss at the start of collapse. It merely wouldn't be able to suspend anything below the dynamited floor.

I would speculate that after the first ten floors or so, the explosive-triggered collapse would look materially identical to the historical WTC collapses. The mechanism described by NIST no longer applies once the upper block has gained some speed, and we see more traditional fracture and buckling of lower columns due to sheer overload.

The distinction between demolition and What Really Happened will be in the first few floors, where the interior sagging mechanism is still considerable, and especially in the collapse initiation, which looks absolutely nothing like any explosive phenomenon.

[babazaroni]

Yes I do and, to a large extent, this aspect of the discussion is not related to the original question.

As I said, the fact that the removal one one floors worth of core would lead to a 'global collapse' is really all I wanted to ask.

Yes, it does not relate to the original question.

But it does relate to your most recent question about the perimeter columns bowing inward.

[coughymachine]

Yes, it does not relate to the original question.

But it does relate to your most recent question about the perimeter columns bowing inward.
I understand. I lost sight of the thrust of my original post and went off at a tangent, exploring one aspect of an earlier response that has, on reflection, nothing to do with my original scenario.

[NobbyNobbs]

Happily, though I'm not sure my 'reasons' have any bearing on the answers.

I don't understand the collapse of either WTC1, WTC2 or WTC7. I am not an engineer and would be wasting my time trying to read the technical aspects of NIST's report. I have seen a lot of explanations from both sides of the debate and want to know what's possible and what's not.

In this specific scenario, I want to know whether a building, such as WTC1 could be brought down in much the same way WTC1 came down, by simultaneously blowing the core columns at one (or more) floors.

Where I go from there, I don't know.

Where you might go from here, if you are entertaining this as a viable theory of what actually happened, is to ask yourself what resources would be required to completely remove the core columns of one entire floor.

[grmcdorman]

It should also be pointed out that the consensus appears to be that the collapse would be superficially similar - that is, similar overall, but different in the details (in particular, bowing of the exterior columns - at least in time, and possibly absent altogether in the hypothetical remove-one-floor scenario).

[Architect]

Obviously I've got a bit of a thing about it at the moment, but I was just musing how this debate would have gone if it had been run on LCW.....

....certainly not lots of people saying things along the lines of "dunno, what about etc etc" and actually explaining it!


Coughy, you're not my pal Strawman are you?

[coughymachine]

Where you might go from here, if you are entertaining this as a viable theory of what actually happened, is to ask yourself what resources would be required to completely remove the core columns of one entire floor.
If I were to try and develop this as a viable theory, I would need to ask myself what resources would be needed to remove the final ~1/3 of the remaining columns; how the planes were guided with the precision necessary to remove the first ~2/3; and how that resource withstood the impact and subsequent fires.

[coughymachine]

Obviously I've got a bit of a thing about it at the moment, but I was just musing how this debate would have gone if it had been run on LCW.....

....certainly not lots of people saying things along the lines of "dunno, what about etc etc" and actually explaining it!


Coughy, you're not my pal Strawman are you?
No.

If you and I have ever debated, then I will have done so as 'coughymachine'. I can also assure you that, if a similar line of enquiry is being explored elsewhere, I am acting completely independently of them. I've not even seen Loose Change let alone been inclined to go and discuss 9/11 with them.

You will no doubt learn that I won't be agreeing with you guys a lot, but I am transparent and straight-talking.

[grmcdorman]

If I were to try and develop this as a viable theory, I would need to ask myself what resources would be needed to remove the final ~1/3 of the remaining columns; how the planes were guided with the precision necessary to remove the first ~2/3; and how that resource withstood the impact and subsequent fires.And that, in a nutshell, is what separates the CTs from the rationalists. It's the sort of question that they never seem to ask, let alone answer when posed to them.

coughymachine, good job. You did come in looking similar to some CTrs (as mentioned, their MO is often "just asking questions" and initial misrepresentation of their stance), but it became clear over time that was probably just a coincidence.

[Architect]

No.

If you and I have ever debated, then I will have done so as 'coughymachine'. I can also assure you that, if a similar line of enquiry is being explored elsewhere, I am acting completely independently of them. I've not even seen Loose Change let alone been inclined to go and discuss 9/11 with them.

You will no doubt learn that I won't be agreeing with you guys a lot, but I am transparent and straight-talking.


I wasn't being sarcastic - Strawman seemed like a very sensible man, and was approaching the issue in a similar way to you (but with a stronger CT bent).

[babazaroni]

If I were to try and develop this as a viable theory, I would need to ask myself what resources would be needed to remove the final ~1/3 of the remaining columns; how the planes were guided with the precision necessary to remove the first ~2/3; and how that resource withstood the impact and subsequent fires.

Ask yourself first why it was so necessary for the buildings to collapse at the expense of increasing the probability of getting caught exponentially?

[coughymachine]

Ask yourself first why it was so necessary for the buildings to collapse at the expense of increasing the probability of getting caught exponentially?
No. If it's not possible, motivation is irrelevant.

[qarnos]

in your scenario i would expect it to look more like this:

http://img.photobucket.com/albums/v190/defaultdotxbe/WTCfailingperimetercolumns.jpg

as the gravity load is transferred to the perimeter collumns via the hat truss, they are overloaded and fail

In your example, the collapse of the building is causing the perimeter columns to buckle.

On 9/11, it was the buckling of the perimeter columns which caused the collapse.

[einsteen]

And Lebowksi what was the cause of the buckling?

[e^n]

And Lebowksi what was the cause of the buckling?

I'm not sure if you're baiting here but I will bite, the buckling was undeniably caused by inward displacement of perimeter columns which was most likely caused by trusses sagging and exerting 'pull in' forces.

[babazaroni]

No. If it's not possible, motivation is irrelevant.

Well you can never really know for sure, so motivation is relevant.

[Gravy]

You mean Judy "elastic collisions" Wood

btw. here is Bazant's solid mass collapse model

A little bit a crappy picture for such a professional paper.That's why structural engineers use calculations.

[Gravy]

And Lebowksi what was the cause of the buckling?You have to be freaking kidding. Why are you wasting people's time like this? You can't even be bothered to read NIST's FAQ?

[ConspiRaider]

And Lebowksi what was the cause of the buckling?
Since I'm part Polish I'll take this one.

The Cause of the Buckling is an old folk tale oft-told by the hardy peoples of the Adirondacks.

Hooftie was an immature male moose (called a "buckling" by the fun-loving cannibalistic hill people of this rugged region) who was eagerly awaiting the arrival of his antlers. He longed to hear the other bucklings and fawnlings say: "Yo, look at the rack on that one!" as he strolled past in search of succulent mulberry leaves and telephone pole bark and mango rinds (rich in vitamoose B-12, terrific for antler growth).

But Hooftie's antlers never grew, alas, and a lass the deprived buckling would never get. Apparently Hooftie wolfed down an abandoned cell phone next to a telephone pole off of which he would soon be bark-stripping. The LCD stuff in the low calorie cell phone played hell with his antler hormones once consumed. That nixed the majestic rack he so desperately yearned.

Hooftie the Buckling's cause, to the end of his days, was trying to figure out how to answer the pesky phone lodged in his moosy gut. He was losing lots of sleep over the ring tone "Memorable Scenes and Lines from Deliverance" (especially the Pig Scene with the hillbillies) and tried all kinds of ways to turn it off. He'd jump, roll, leap over a fence and do a belly flop right on the barbed wire top to try and hit the "End" button. But nothing worked.

Eventually a Bigfoot tribe buried poor Hooftie after he'd passed on (due to having 41 anxiety attacks in a 6 minute period, still a record in those parts). Some say you can still hear the haunting tones of Ned Beatty wafting spookily over the glades and forests and mango groves of the mysterious and foreboding Adirondacks late at night...

[coughymachine]

Well you can never really know for sure, so motivation is relevant.
Well, if you'd like to set out how it might have been possible, I'll address the issue of motivation.

[gumboot]

Well, if you'd like to set out how it might have been possible, I'll address the issue of motivation.



Would you mind explaining what the purpose was behind you asking this question?

-Gumboot

[qarnos]

And Lebowksi what was the cause of the buckling?

Looks like others have beaten me to it, but since the question was directed at me, I will also provide a response.

The buckling of the perimeter columns was caused by the contraction of the floor trusses as they cooled from the fire, after initially expanding and sagging when the heat was more intense.

[coughymachine]

Would you mind explaining what the purpose was behind you asking this question?

-Gumboot
babazaroni earlier asked me what the motivation might be for bringing the towers down, given the 'exponential' risk of getting caught. I replied to the effect that, until I am satisfied it was possible to bring them down with explosives, I am not interested in motivation (my exact words being "if it's not possible, motivation is irrelevant"). In other words, this is an angle I'm not interested in exploring at this stage.

babazaroni then pressed the point, suggesting that it might be possible and that the motivation was thus relevant. So I simply invited him to set out how it might be possible, at which point I'll address motivation.

[gumboot]

babazaroni earlier asked me what the motivation might be for bringing the towers down, given the 'exponential' risk of getting caught. I replied to the effect that, until I am satisfied it was possible to bring them down with explosives, I am not interested in motivation (my exact words being "if it's not possible, motivation is irrelevant"). In other words, this is an angle I'm not interested in exploring at this stage.

babazaroni then pressed the point, suggesting that it might be possible and that the motivation was thus relevant. So I simply invited him to set out how it might be possible, at which point I'll address motivation.


No, I mean what was the purpose behind asking the question in the OP?

(By the way my earlier comment about "Truthers" was not directed at you specifically, but more a general musing that I have had often, that I was reminded of by your questions) :)

-Gumboot

[coughymachine]

No, I mean what was the purpose behind asking the question in the OP?

Ah, sorry - I misunderstood.

As for the OP...

I don't recall the exact line of enquiry, but I was discussing some aspect of the collapse with someone at another forum. We touched on CD vs non-CD collapse and he started a new thread dedicated to explaining why a CD would not bring the towers down in the way we observed on 9/11.

To my mind (which is, admittedly, non-technical) his explanation made no sense and I quizzed him about it. My view was, if the towers couldn't have been brought down by simultaneously removing the core at x number of floors, then they couldn't be brought down by local impacts and fires.

Unfortunately, he left the forum before we'd finished and with a great many questions unanswered.

I'm not sure my question adds to the debate, but I wanted an answer, having spent time discussing it.

As for being a 'Twoofer', well, I guess I'm going to have to disappoint you. Whether I'm a different breed to those you commonly experience, time will tell I guess.

[Architect]

Coughy, if you've got an account at LCF it may be worth you inviting strawman over to join this debate, as much of his thinking/questions seems to lie in a similar area. I'd ask him myself, but obviously I can't.

[coughymachine]

Coughy, if you've got an account at LCF it may be worth you inviting strawman over to join this debate, as much of his thinking/questions seems to lie in a similar area. I'd ask him myself, but obviously I can't.
I don't have an account over there.

I'd pretty much finished with this for now. By suggesting I invite strawman over here, you've made me wonder whether I've missed something...

[Architect]

Strawman's hypothesis seems to resolve around whether the controlled demolition of approximately 4 to 6 stories would result in a cetrain global collapse and, I suspect, whether the visible evidence of this would in fact be very similar to the events of 911.

I hedge a little there because we were laregely conducting the discussion by PM, and of course it was curtailed somewhat when I got booted off. Which was a shame, because it was a good example of how these issues can be discussed sensibly, rather than just "LOL! CD!!! OBVIOUS MAN!!!"

[einsteen]

The buckling of the perimeter columns was caused by the contraction of the floor trusses as they cooled from the fire, after initially expanding and sagging when the heat was more intense.

If the force is enough to pull in the perimeter columns the force should also be enough to pull them outwards during the heating. And metal doesn't become shorter if it cools back to its initial cold temperature unless it bends, but I don't believe the bi-metal theory. If you remove just a part of the core then the perimeter columns are overloaded and then they also might bend, that could be in two directions but since the trusses are still there it should be inwards. btw. I'm no denier, I saw it with my own eyes :) , I mean the behaviour at the outside

[Gravy]

If the force is enough to pull in the perimeter columns the force should also be enough to pull them outwards during the heating. And metal doesn't become shorter if it cools back to its initial cold temperature unless it bends, but I don't believe the bi-metal theory. If you remove just a part of the core then the perimeter columns are overloaded and then they also might bend, that could be in two directions but since the trusses are still there it should be inwards. btw. I'm no denier, I saw it with my own eyes :) , I mean the behaviour at the outsideI suggest that you read the NIST report and respond to its detailed analysis of this subject. Will you do that?

[coughymachine]

Strawman's hypothesis seems to resolve around whether the controlled demolition of approximately 4 to 6 stories would result in a cetrain global collapse and, I suspect, whether the visible evidence of this would in fact be very similar to the events of 911.

I hedge a little there because we were laregely conducting the discussion by PM, and of course it was curtailed somewhat when I got booted off. Which was a shame, because it was a good example of how these issues can be discussed sensibly, rather than just "LOL! CD!!! OBVIOUS MAN!!!"
Got it.

I can't say this hasn't crossed my mind but there are problems, as I outlined earlier. The placing of explosives on a limited number of floors, whilst minimising the preparatory work and time, introduces the added complication of having to ensure the planes impact the right floors. Then, of course, the material has to survive that impact and the resulting fires.

The other issue is that the nature of the collapse - the erupting material at all floors - that has prompted speculation that the building was brought down with explosives, cannot be explained with this scaled-back CD methodology.

In other words, the very thing that has sparked the debate is not explained by the solution.

[einsteen]

Gravy, the next time I talk about it I promise I've read all those 132 pages...

http://wtc.nist.gov/pubs/Media_Public_Briefing_040505_final.pdf

[chipmunk stew]

If the force is enough to pull in the perimeter columns the force should also be enough to pull them outwards during the heating. And metal doesn't become shorter if it cools back to its initial cold temperature unless it bends, but I don't believe the bi-metal theory. If you remove just a part of the core then the perimeter columns are overloaded and then they also might bend, that could be in two directions but since the trusses are still there it should be inwards. btw. I'm no denier, I saw it with my own eyes :) , I mean the behaviour at the outside
You've been discussing this subject for how long, einsteen? Months, at least. You've posted hundreds (if not thousands) of comments and questions on the topic here and elsewhere, and received at least double that in response.

How is it, then, that you strung together this paragraph of words, all of which have the potential to say something meaningful, but in the configuration you have chosen results in a steaming pile of gibberish?

[Gravy]

Gravy, the next time I talk about it I promise I've read all those 132 pages...

http://wtc.nist.gov/pubs/Media_Public_Briefing_040505_final.pdfRather than reading a summary of the investigation's progress as of April, 2005, I suggest that you read the relevant sections (http://wtc.nist.gov/oct05NCSTAR1-6index.htm) of the final report. Will you do that?

[einsteen]

Sounds great.

Chipmunk, to be honest I'm only interested in everything after collapse initiation...

[defaultdotxbe]

In your example, the collapse of the building is causing the perimeter columns to buckle.

On 9/11, it was the buckling of the perimeter columns which caused the collapse.
i know, im saying this is what i would expect to happen in coughy's "core removal" scenario

[aggle-rithm]

Sounds great.

Chipmunk, to be honest I'm only interested in everything after collapse initiation...

...because that's where the mystery lies. Wherever there is mystery, there's still a dim hope of conspiracy.

[babazaroni]

If I were to try and develop this as a viable theory, I would need to ask myself what resources would be needed to remove the final ~1/3 of the remaining columns; how the planes were guided with the precision necessary to remove the first ~2/3; and how that resource withstood the impact and subsequent fires.

First you have the situation backwards. The impact removed approx 1/3 of the core columns. Second, you don't need to remove all the columns for the building to collapse.

The building has already adjusted (tilted) to compensate for the perimeter and core columns that were damage/destroyed, putting additional stress on the remaining columns.

Now use the fire to your advantage. Imagine sections of the core columns with thick steel plates welded to the sides of the wide flange sections, to create a pocket stuffed with thermite/thermate. As the fire moves throughout the building, these sections ignite on their own. The thermite will burn through both the applied plates and the core column. The building compensates a little more as core columns weaken/fail till the remaining columns fail just from stress.

Of course this requires much work, and thus the possibility of getting caught skyrockets, but in the mind of a fantasist, if it's possible, then it happened.

Which is exactly my point, the risk/reward ratio of such an operation is relevant.

The Pentagon did not collapse, the towers did not need to as well.

[coughymachine]

Since this is still being discussed, I might as well chip in.

Is there visual evidence that the inward buckling of the perimeter columns occured during the collapse of both towers and, if so, is there visual evidence of how many sides buckled in this way?

[rwguinn]

Looks like others have beaten me to it, but since the question was directed at me, I will also provide a response.

The buckling of the perimeter columns was caused by the contraction of the floor trusses as they cooled from the fire, after initially expanding and sagging when the heat was more intense.

Go look at the Purdue U. (http://www.cs.purdue.edu/homes/cmh/simulation/phase4/index.html) animation and FEM of the A/C-Building impact. See the loss of core columns. See the sagging floor trusses.
There is no ONE answer to a systems failure problem-and that is what we had -- A total system failure. Discussion here (http://forums.randi.org/showthread.php?t=82940)

[Pardalis]

Is there visual evidence that the inward buckling of the perimeter columns occured during the collapse of both towers and, if so, is there visual evidence of how many sides buckled in this way?

I believe the perimeter columns bowed inwards just prior to the collapse. I think it's everywhere in the NIST Report if you care to look.

[babazaroni]

Since this is still being discussed, I might as well chip in.

Is there visual evidence that the inward buckling of the perimeter columns occured during the collapse of both towers and, if so, is there visual evidence of how many sides buckled in this way?

Yes, numerous videos and photos.

Here is one:

-5405555553528290546&q=south+tower+church

[coughymachine]

First you have the situation backwards. The impact removed approx 1/3 of the core columns. Second, you don't need to remove all the columns for the building to collapse.

The building has already adjusted (tilted) to compensate for the perimeter and core columns that were damage/destroyed, putting additional stress on the remaining columns.

Now use the fire to your advantage. Imagine sections of the core columns with thick steel plates welded to the sides of the wide flange sections, to create a pocket stuffed with thermite/thermate. As the fire moves throughout the building, these sections ignite on their own. The thermite will burn through both the applied plates and the core column. The building compensates a little more as core columns weaken/fail till the remaining columns fail just from stress.

Of course this is requires much work, and thus the possibility of getting caught skyrockets, but in the mind of a fantasist, if it's possible, then it happened.

Which is exactly my point, the risk/reward ratio of such an operation is relevant.

The Pentagon did not collapse, the towers did not need to as well.
I don't understand why you're pressing this point so hard. This started out as a very simply question and you seem to want to coax me into developing a fully-fledged theory as a result.

From my perspective, and regardless of whether all of the columns need to be removed or not, the motivation only becomes relevant if the mechanism is viable. If explosives were planted at one floor but there was no way of ensuring the plane hit that floor, and no way of ensuring the material would survive the impact and fires, I see little point in speculating about motivation. Why would I speculate about the motivation for doing something that is impossible?

Now, if you're saying it is possible to ensure the planes hit a specific floor (twice) and that the material could survive (twice), then please set it out.

And what has any of this to do with the Pentagon, which did collapse in the area it was struck?

[coughymachine]

Yes, numerous videos and photos.

Here is one:

-5405555553528290546&q=south+tower+church
I can't get this to play. Could you post the link please?

[Pardalis]

I can't get this to play. Could you post the link please?

There's also the NIST Report you know...

[coughymachine]

There's also the NIST Report you know...
Okay.

[babazaroni]

I don't understand why you're pressing this point so hard. This started out as a very simply question and you seem to want to coax me into developing a fully-fledged theory as a result.

From my perspective, and regardless of whether all of the columns need to be removed or not, the motivation only becomes relevant if the mechanism is viable. If explosives were planted at one floor but there was no way of ensuring the plane hit that floor, and no way of ensuring the material would survive the impact and fires, I see little point in speculating about motivation. Why would I speculate about the motivation for doing something that is impossible?

Now, if you're saying it is possible to ensure the planes hit a specific floor (twice) and that the material could survive (twice), then please set it out.

And what has any of this to do with the Pentagon, which did collapse in the area it was struck?

I'm not pressing. You asked me for a possible scenario to justify motive relevance.

Where did I say the plane had to hit a specific floor?

Why would the pockets need to survive the fire? The fire is what ignites the pockets.

The public hardly noticed a small section of the Pentagon collapsing into the damaged area.

The point is the buildings did not need to collapse, even though it is possible.

Just because you can't think of a way for a building to collapse, does not mean it is not possible.

Try the video again, I fixed the link.

[coughymachine]

There's also the NIST Report you know...
I did a quick scan of NIST NCSTAR1-6. It offers 1 photograph of the south face of WTC1 and another of the east face of WTC2. To your knowledge, are there any others? I specifically want to know whether this inward buckling was observed along all four faces of both towers.

I know I could trawl through the whole thing myself, but part of the purpose of entering a discussion is to draw from your knowledge.

[chipmunk stew]

I did a quick scan of NIST NCSTAR1-6. It offers 1 photograph of the south face of WTC1 and another of the east face of WTC2. To your knowledge, are there any others? I specifically want to know whether this inward buckling was observed along all four faces of both towers.

I know I could trawl through the whole thing myself, but part of the purpose of entering a discussion is to draw from your knowledge.
It was mainly observed on the faces you mention. One face of each tower.

[coughymachine]

I'm not pressing. You asked me for a possible scenario to justify motive relevance.

Where did I say the plane had to hit a specific floor?

Why would the pockets need to survive the fire? The fire is what ignites the pockets.

The public hardly noticed a small section of the Pentagon collapsing into the damaged area.

The point is the buildings did not need to collapse, even though it is possible.

Just because you can't think of a way for a building to collapse, does not mean it is not possible.

Try the video again, I fixed the link.
Either I'm missing something or else I think you need to review our exchange.

Earlier, I wrote

If I were to try and develop this as a viable theory, I would need to ask myself what resources would be needed to remove the final ~1/3 of the remaining columns; how the planes were guided with the precision necessary to remove the first ~2/3; and how that resource withstood the impact and subsequent fires.

This was in response to a post from NobbyNobb (sp?)

You then responded with...

Ask yourself first why it was so necessary for the buildings to collapse at the expense of increasing the probability of getting caught exponentially?

The reason I don't see the relevance of motivation here is that, as set out above, I don't see how a single-floor CD would work, given that the CD would have to initiate at the same floor as the planes impacted - twice. This requires a precision that is improbable at best. Also, I don't see how the hypothetical charges could survive the impact and fires.

You have nonetheless pressed me to explain a motivation for something I don't yet believe was possible. So my request is for you to explain how two pilots could guide their jumbos into the towers at the exact floors the hypothetical charges were located at. Then explain why the hypothetical charges didn't detonate immediately. If you can show how this could be done, I'll try and address the motivation issue.

And again, what has the Pentagon got to do with this?

[Architect]

My head is beginning to hurt reading this exchange. Are you sure that you two are actually disagreeing with each other, rather than just (as I suspect) misunderstanding?

In passing, it seems to me quite reasonable to set to one side issues such as motive until such time as the supposed result thereof is shown to be credible. Otherwise Judy's death ray beckons......

[rwguinn]

My head is beginning to hurt reading this exchange. Are you sure that you two are actually disagreeing with each other, rather than just (as I suspect) misunderstanding?

In passing, it seems to me quite reasonable to set to one side issues such as motive until such time as the supposed result thereof is shown to be credible. Otherwise Judy's death ray beckons......

What he said...
One must address the argument, not the motive.
Robert's Rules of Order.
Lest the Marquis of Queensbury take over*









*Do i get an award for a John Wayne reference? An "Irish" one at that

[babazaroni]

Well, if you'd like to set out how it might have been possible, I'll address the issue of motivation.

If you don't want a response, then don't ask.


The reason I don't see the relevance of motivation here is that, as set out above, I don't see how a single-floor CD would work, given that the CD would have to initiate at the same floor as the planes impacted - twice.
This requires a precision that is improbable at best.


Wrong assumption. Single floor cd only not needed. The building already has severe damage at the impact floor. More damage from some of the pockets on this floor plus those on other floors as the fire spreads will cause a global collapse that appears in the area of the most damage.

But even in the unlikely event collapse appears at another area, fire can be used to explain this. After all, fire is what caused the thermite pockets to ignite in the first place.


Also, I don't see how the hypothetical charges could survive the impact and fires.
Thermite/Thermate are not explosive charges. They are cutting agents.

They don't need to survive the fires. They are ignited by the fires.


You have nonetheless pressed me to explain a motivation for something I don't yet believe was possible. So my request is for you to explain how two pilots could guide their jumbos into the towers at the exact floors the hypothetical charges were located at.
Already explained. No need to hit a specific floor. The pockets could be on a 20 floor range.


Then explain why the hypothetical charges didn't detonate immediately. If you can show how this could be done, I'll try and address the motivation issue.
Thats the whole point. The fire ignites the pockets. Again, thermite/thermate are not explosives. They don't detonate. They burn.

Welded on plates have a good chance of surviving impact in areas not directly hit by debris.

A building system does not need for all it's damage to happen at the same time, and at the same point for it to fail.


And again, what has the Pentagon got to do with this?That global collapse of a building is not needed to incite a war. Only a small section of the Pentagon was destroyed. Plenty of terror was generated just by the impacts.

I believe it is possible to collapse a building in this manner. I'm sure an expert can think of a better scenario.

Of course your chances of getting caught go up astronomically. Thus risk/reward are relevent.

If you don't think it possible, then no need to continue the discussion.

[CurtC]

I specifically want to know whether this inward buckling was observed along all four faces of both towers.

My understanding is that the columns being pulled inwards happened on one face of each tower. Look at it this way: it might have eventually happened on all four, but buckling on one face is enough to initiate the collapse, so the buckling never had a chance to get to the other three.

Also, each tower tilted as it fell, towards the side with the buckling. I'm sure this is true with the South Tower, and I think it is also true for the North.

[coughymachine]

If you don't want a response, then don't ask.

So, what you're saying is this:

Charges could have been planted on a very small number of floors only. This 'range' of floors would have given the pilots enough room for error. The fires that followed the impact eventually ignited the charges, which compounded the impact damage and initiated a 'global collapse'.

But, presumably, you're also agreeing with the answers given earlier, that the towers would have undergone a 'global collapse' as the result of the impacts and fires alone.

So in an already damaged building, charges would have been superfluous.

[coughymachine]

It was mainly observed on the faces you mention. One face of each tower.
One face on each tower and, if I'm not mistaken, the side opposite to the impact. Why the opposite side? Any ideas?

[coughymachine]

That global collapse of a building is not needed to incite a war. Only a small section of the Pentagon was destroyed. Plenty of terror was generated just by the impacts.
I would be interested in any suggestions you might have as to how the 'global collapse' of the Pentagon could have been initiated by the impact of a hijacked aircraft.

[chipmunk stew]

One face on each tower and, if I'm not mistaken, the side opposite to the impact. Why the opposite side? Any ideas?
The plane impact pushed a concentration of the fuels the fire would consume to the other side of the building as it passed through.

[coughymachine]

The plane impact pushed a concentration of the fuels the fire would consume to the other side of the building as it passed through.
But presumably, the far sides needed to cool first in order to have the trusses contract, pulling the perimeter columns in. In which case, I would assume less fuel was pushed over there, or somehow, the fires on the opposite side to the impacts (in both buildings) died down more quickly.

[Dave Rogers]

But presumably, the far sides needed to cool first in order to have the trusses contract, pulling the perimeter columns in. In which case, I would assume less fuel was pushed over there, or somehow, the fires on the opposite side to the impacts (in both buildings) died down more quickly.

Not necessarily. Two possible arguments:

1. If there was less fuel on the impact side, the fire might be less intense and lead to less sagging of the trusses in the first place, so that side wouldn't be as likely to collapse even if it cooled down sooner.

2. If the avgas was mostly concentrated on the side opposite the impact, it would act as an accelerant on that side in preference to the impact side, so the fires opposite the impact would burn hotter and faster and burn out quicker.

I haven't looked at the fire modelling in the NIST report in detail, but I suspect the full answer to your question lies therein.

Dave

[babazaroni]

So, what you're saying is this:

Charges could have been planted on a very small number of floors only. This 'range' of floors would have given the pilots enough room for error. The fires that followed the impact eventually ignited the charges, which compounded the impact damage and initiated a 'global collapse'.

But, presumably, you're also agreeing with the answers given earlier, that the towers would have undergone a 'global collapse' as the result of the impacts and fires alone.

So in an already damaged building, charges would have been superfluous.

Yes, that is a good summary and I agree with the previous answers that impact damage and fires caused the collapses. In fact, as Architect has pointed out before, there is a study that shows fire alone could have caused the collapses.

But this was not known before hand.

I know few approach this from my perspective, but the risk/reward ratio is the most important aspect of 9/11 that convinces me it was not a government conspiracy.

[coughymachine]

I haven't looked at the fire modelling in the NIST report in detail, but I suspect the full answer to your question lies therein.
Off topic...

Just noticed your location. I'm near Stanton, which is mid-way between Bury and Diss.

[chipmunk stew]

I know few approach this from my perspective, but the risk/reward ratio is the most important aspect of 9/11 that convinces me it was not a government conspiracy.
Indeed, that's one of the earliest and most important analyses in the planning of almost any inherently risky project.

[Architect]

Yes, that is a good summary and I agree with the previous answers that impact damage and fires caused the collapses. In fact, as Architect has pointed out before, there is a study that shows fire alone could have caused the collapses.


Two: Edinburgh University and Ove Arup.

[R.Mackey]

Not necessarily. Two possible arguments:

1. If there was less fuel on the impact side, the fire might be less intense and lead to less sagging of the trusses in the first place, so that side wouldn't be as likely to collapse even if it cooled down sooner.

2. If the avgas was mostly concentrated on the side opposite the impact, it would act as an accelerant on that side in preference to the impact side, so the fires opposite the impact would burn hotter and faster and burn out quicker.

I haven't looked at the fire modelling in the NIST report in detail, but I suspect the full answer to your question lies therein.

Your suspicion is correct. The observed fire progression, and the impact models in NCSTAR1-2, suggest that the majority of combustibles on the impact floors were preferentially pushed to the side away from the impact. They appear to have stacked up against the opposite perimeter wall, which was not damaged badly enough for most office contents to be pushed through and out on the street. See NIST NCSTAR1-5 for the fire, 1-6 for an explanation of the collapses. Section 2.3.4 of NIST NCSTAR1-5, in particular, describes the piling of debris seen.

There is also the fact that, facing impact, damage to the floor trusses was highest, causing large areas of floor failure instantly, and this reduced the ability of the floors to later pull inwards on that side.

A third and major factor is that the fire dynamics were guided by the prevailing winds. See pg. 20 of NCSTAR1-5 for a quick summary of WTC 1's fire dynamics, where wind is cited as the main driver.

[chipmunk stew]

Your suspicion is correct. The observed fire progression, and the impact models in NCSTAR1-2, suggest that the majority of combustibles on the impact floors were preferentially pushed to the side away from the impact. They appear to have stacked up against the opposite perimeter wall, which was not damaged badly enough for most office contents to be pushed through and out on the street. See NIST NCSTAR1-5 for the fire, 1-6 for an explanation of the collapses. Section 2.3.4 of NIST NCSTAR1-5, in particular, describes the piling of debris seen.

There is also the fact that, facing impact, damage to the floor trusses was highest, causing large areas of floor failure instantly, and this reduced the ability of the floors to later pull inwards on that side.

A third and major factor is that the fire dynamics were guided by the prevailing winds. See pg. 20 of NCSTAR1-5 for a quick summary of WTC 1's fire dynamics, where wind is cited as the main driver.
I was just about to post the first two points, but without the citations, so thanks for doing a more thorough job than I would have. I was not aware of the third point, about the effect the wind had. I'm off to look it up right now. Thanks!

[coughymachine]

Yes, that is a good summary and I agree with the previous answers that impact damage and fires caused the collapses. In fact, as Architect has pointed out before, there is a study that shows fire alone could have caused the collapses.

But this was not known before hand.

I know few approach this from my perspective, but the risk/reward ratio is the most important aspect of 9/11 that convinces me it was not a government conspiracy.
Okay, so you've shown how the charges could have been planted on a limited number of floors. This 'range' was nonetheless wide enough to allow for piloting error. And the location, on the opposite side from the impact, ensured that the charges ignited sometime after impact, compounding the damage and bringing the buildings down.

What risks would you say are associated with this plan (over and above the risks already incorporated into a non-CD plan)?

[rwguinn]

Your suspicion is correct. The observed fire progression, and the impact models in NCSTAR1-2, suggest that the majority of combustibles on the impact floors were preferentially pushed to the side away from the impact. They appear to have stacked up against the opposite perimeter wall, which was not damaged badly enough for most office contents to be pushed through and out on the street. See NIST NCSTAR1-5 for the fire, 1-6 for an explanation of the collapses. Section 2.3.4 of NIST NCSTAR1-5, in particular, describes the piling of debris seen.

There is also the fact that, facing impact, damage to the floor trusses was highest, causing large areas of floor failure instantly, and this reduced the ability of the floors to later pull inwards on that side.

A third and major factor is that the fire dynamics were guided by the prevailing winds. See pg. 20 of NCSTAR1-5 for a quick summary of WTC 1's fire dynamics, where wind is cited as the main driver.

Don't forget the (to me, anyway) obvious:
With the tremendous damage to the side of the building bearing the brunt of the impact, the remaining columns had to bear the weight of the floors above.
Those columns were on the opposite side of the building from impact... Add in the temperature effects due to your hypothesis, and where else could it start?

[babazaroni]

What risks would you say are associated with this plan (over and above the risks already incorporated into a non-CD plan)?

Installing the cutting agents over so many floors would require stealth or building security assistance, which means more people involved.

If the plan failed, then more cover-up would be required to remove evidence in the still standing buildings.

The pile clean-up would certainly reveal columns with bizarre damage, thus requiring more cover up operations and more people.

But even if the risks could be reduced, the reward part of the ratio kicks in. I feel 99 percent of the rewards were generated by the impacts.

I think even if the hijackers crashed the planes immediately after takeover, there would still be enough to incite war. But if you are a suicide hijacker, why not take it as far as you can?

[CurtC]

One face on each tower and, if I'm not mistaken, the side opposite to the impact. Why the opposite side? Any ideas?
That's not the case. For the North Tower, the impact was on the North side, and it was the South side that buckled. But for the South Tower, which was hit on the South side, the East face was the one that buckled.

There is another point you may have missed. Each tower's cross-section was square overall, but the core was rectangular. One one pair of faces, the floor trusses spanned only 35 feet, but on the other pair, the floor trusses had to span 60 feet. Both towers buckled on the side with the 60-foot floor trusses.

But presumably, the far sides needed to cool first in order to have the trusses contract, pulling the perimeter columns in.
It was not the cooling and contracting of the floor trusses that caused them to pull the perimeter columns in. It was the fact that the heavy concrete floor had less strength to support it, the stell floor trusses having been weakened by the fire. When the floors sagged, and remained connected at the end points of the floor trusses, that caused the perimeter columns to be pulled inwards.

[R.Mackey]

It was not the cooling and contracting of the floor trusses that caused them to pull the perimeter columns in. It was the fact that the heavy concrete floor had less strength to support it, the stell floor trusses having been weakened by the fire. When the floors sagged, and remained connected at the end points of the floor trusses, that caused the perimeter columns to be pulled inwards.

To be fair, it's probably a mixture. You do not require cooling to get an inward pull -- NIST describes in detail the effect of heating and sagging into a caternary shape, and this alone creates a pull. However, the fires were beginning to diminish (particularly for WTC 1) in the collapse initiation region, suggesting that the floors were also cooling, which adds yet another contribution to the inward pull.

This combination of mechanisms makes the eventual collapse all but guaranteed, once the fireproofing is gone.

[Newtons Bit]

Since there seems to be some misunderstanding of what caused the perimeter columns in, I'll provide some erudition. That's a big word, can someone see if I used it right? :D

Anyways, the columns likely weren't just "buckling". See my response toGordon Ross's "paper" (http://newtonsbit.blogspot.com/2007/05/failure-of-truth-movements-engineer.html) for a little more information on buckling.

What really caused the perimeter columns to bow inwards, was a loss of bending stiffness in the trusses due to the fires. When the fires heated the trusses up, two very important structural properties were weakened: the yield stress and modulus of elasticity. The more important one in this case being the modulus of elasticity, which is basically a way of measuring how much a member deflects under a unit load. As this decreased, it stopped being able to resist the "bending". What this means is that the truss stops being a truss and becomes more like a cable. It deflects a large amount and pulls on it's connections, rather than just having a vertical reaction.

I believe the shear connection from the truss to the column was two 5/8" diamater A307 bolts, which together have a shear strength of 11,000 lb. If we take that as a horizontal force applied over two stories, the deflection is:

P*(L^3)/(48*E*I)

E=29000
I = 248in^3
L = 296in (12'4" floor height)

Or 0.826in. Which doesn't appear to be that much, however it is very significant. The bending moment acting on the column is now 814 k*in.

But wait, there's more! The bending moment induced from the axial load is now Axial Load * 0.826in. If the axial load is several hundred kips, this could be very important. But what is more important, is that the moment from the axial force and the induced displacement of the truss just caused the column to bend more. It will either keep bending until it breaks or until it reaches some equilibrium. This is what is known as p-delta. It's a bitch.

If more than one floor has been damaged, this effect is of course worse. Depending upon what the axial force is and what the buckling stress of the column is, this could cause some very large deflections.

[Augustine]

I believe the shear connection from the truss to the column was two 5/8" diameter A307 bolts

The bolts were either A325 or A490 (NCSTAR 1-3E) or A325 (FEMA App B). The bolts were just erection bolts; around the perimeter, there was a 3/8" x 4" A36 gusset plate welded to the top of the truss. (Some discussion about this in NCSTAR 1-6C, and in the SEAOC boards after the NOVA special on the Towers aired - Charlie Carter from AISC in particular.) Given that, the force on the perimeter columns may have been of a much greater magnitude.

[coughymachine]

But even if the risks could be reduced, the reward part of the ratio kicks in. I feel 99 percent of the rewards were generated by the impacts.
I think, before we can explore the issue of risk vs reward, we need to agree what the ultimate purpose of a hypothetical false flag op would have been and whether the towers needed to be brought down in order to achieve it.

Also, we need to establish the scale of the operation in order to assess what additional risk was being taken to rig the towers for CD over and above the risks that had already been taken.

To begin with then, let's look at the hypothetical ultimate goal. What do you think it might have been?

[gumboot]

I think, before we can explore the issue of risk vs reward, we need to agree what the ultimate purpose of a hypothetical false flag op would have been and whether the towers needed to be brought down in order to achieve it.

Also, we need to establish the scale of the operation in order to assess what additional risk was being taken to rig the towers for CD over and above the risks that had already been taken.

To begin with then, let's look at the hypothetical ultimate goal. What do you think it might have been?



I don't know about anyone else, but I'm not interested in hypotheticals. My only interest is what did happen, not what could have happened. The September 11 Attacks were carried out by Radical Islamic terrorists belonging to Al Qaeda, not the US Government.

-Gumboot

[coughymachine]

I don't know about anyone else, but I'm not interested in hypotheticals. My only interest is what did happen, not what could have happened. The September 11 Attacks were carried out by Radical Islamic terrorists belonging to Al Qaeda, not the US Government.
I understand how you feel. But this was a route babazaroni was pushing to explore.

[rwguinn]

Since there seems to be some misunderstanding of what caused the perimeter columns in, I'll provide some erudition. That's a big word, can someone see if I used it right? :D

Anyways, the columns likely weren't just "buckling". See my response toGordon Ross's "paper" (http://newtonsbit.blogspot.com/2007/05/failure-of-truth-movements-engineer.html) for a little more information on buckling.

What really caused the perimeter columns to bow inwards, was a loss of bending stiffness in the trusses due to the fires. When the fires heated the trusses up, two very important structural properties were weakened: the yield stress and modulus of elasticity. The more important one in this case being the modulus of elasticity, which is basically a way of measuring how much a member deflects under a unit load. As this decreased, it stopped being able to resist the "bending". What this means is that the truss stops being a truss and becomes more like a cable. It deflects a large amount and pulls on it's connections, rather than just having a vertical reaction.

I believe the shear connection from the truss to the column was two 5/8" diamater A307 bolts, which together have a shear strength of 11,000 lb. If we take that as a horizontal force applied over two stories, the deflection is:

P*(L^3)/(48*E*I)

E=29000
I = 248in^3
L = 296in (12'4" floor height)

Or 0.826in. Which doesn't appear to be that much, however it is very significant. The bending moment acting on the column is now 814 k*in.

But wait, there's more! The bending moment induced from the axial load is now Axial Load * 0.826in. If the axial load is several hundred kips, this could be very important. But what is more important, is that the moment from the axial force and the induced displacement of the truss just caused the column to bend more. It will either keep bending until it breaks or until it reaches some equilibrium. This is what is known as p-delta. It's a bitch.

If more than one floor has been damaged, this effect is of course worse. Depending upon what the axial force is and what the buckling stress of the column is, this could cause some very large deflections.

This is important, folks. I've been trying to say this, in many ways, many times--and obviously failing to get the point across.
The crippling load induced by the floor trusses puts the columns in bending--and it becomes a self-eating watermellon. The situation continues, getting worse all the time, to completion.