WTC7 Revisited

[GregoryUrich]

Introduction:

Many have theorized that the fall time of WTC7 can only be explained by controlled demolition. The fall time indicates there was very little resistance to collapse. This analysis looks at some energy issues in that context to try and quantify the resistance.

Method:

My approach was to use the top 47 floors of WTC1 because the mass and column cross sections are known and the floor area and height was roughly equivalent. Dr. Greening has suggested that the mass was much higher (180,000 tonnes; PE = 166 GJ), but I reject this because NCSTAR1-1 gives thinner (2.5 in) normal concrete floors and WTC7 didn't need the strength of the lower half of WTC1 either for gravity or wind. Making a building 80% heavier than necessary would not be economical.

I used a bottom-up collapse. I have used Dr. Frank Legge's fall time (http://www.journalof911studies.com/volume/200611/911-Acceleration-Study-Proves-Explosive-Demolition.pdf) adjusted for perpective (based on informal input from Dr. Greg Jenkins) which comes out around 6.4-6.5 seconds and I use 6.5 seconds. This is the fall time from the point the roof started to move, indicating global failure. Obviously there were localized failures prior to that (i.e. the penthouses).

I have used linear scaling of the energy loss based on an input which I adjusted iteratively until the required falltime was achieved. This results in a decreasing rate of accelleration. It could be scaled differently of course but my scaling is roughly in line with the relative strength of the structure. Legge arrived at a constant accelleration but the perpective issues will probably change that conclusion when the details are worked out.

I have estimated the energy required for expulsion of air in the following manner. For each 1m increment from the center, I calculated the mass and required acceleration to move the mass to the perimeter, based on the time for the particular floor to collapse. Then I figured out the final velocities and summed the KEs. This is a lower bound as aperature affects will increase amount of energy required. In WTC1, the aperature is never larger than 38% of the facade area due to the external columns and spandrels. Actually, I only calculated the bounds and used a linear interpolation between the bounds which reduces the total somewhat.

Results:

The total mass of the building is calculated to be 103,000 tonnes (roughly 36% of WTC1) with a total PE of 97 GJ. The resistance energy is calculated to be 14 GJ. The energy required to expel air from the building in a progressive bottom up collapse is 28.6 GJ. If a constant acceleration is assumed (supported by Legge's work), then the energy dissipated by resistance is: 1-(6/6.5)^2 ~ 14.8%.

Spread sheets:

Energy (http://www.cool-places.0catch.com/docs/calcCollapseWtc7v1.0.xls)
Air expulsion (http://www.cool-places.0catch.com/docs/calcAirKE.xls)

Discussion:

The "resistance" energy turns out to be less than the energy for air expulsion in a progressive collapse may indicate that the mass assumptions are incorrect or more likely the the collapse was not entirely "progressive" in terms of one floor at a time. Keep in mind that this is NOT a general energy issue as there was more than sufficient PE to destroy the building. However, even using Dr. Greenings PE there is no energy left for plastic buckling, concrete comminution or adiabatic heating.

Conclusion:

While this does not prove controlled demolition, it does raise the question of how, at the point when the structure could no longer hold up the building (weight slightly greater than strength), the resistance of the structure suddenly became zero. In this context some mechanism of assisted collapse is a reasonable line of inquiry.

[johnny karate]

Speaking strictly as a layperson, I'd say you need to submit this research to some type of reputable journal or pursue some other avenue of peer review for it to be taken seriously.

[GregoryUrich]

Speaking strictly as a layperson, I'd say you need to submit this research to some type of reputable journal or pursue some other avenue of peer review for it to be taken seriously.

I view discussing these issues here as part of that process. There are many knowledgeable people here who can help refine this work prior to submission.

[johnny karate]

I view discussing these issues here as part of that process. There are many knowledgeable people here who can help refine this work prior to submission.

Fair enough. But not having read many of your posts before, I'm not entirely sure how readily you would believe what other board members have to say.

[DGM]

Gregory:
I think you have a serious issue with the time of collapse. If the structure under the penthouses had already failed down to the lower floors wouldn't that nullify all of your calculations (acceleration of air)? It seems your assumptions are way to much in favor of collapse.

I'll be interested to see what some of the engineers have to say.

[Sizzler]

I haven't read Legge's paper yet. Are his conclusions generally accepted?

[DGM]

I haven't read Legge's paper yet. Are his conclusions generally accepted?
The calculation is for the global collapse. I have no problem with that. The issue is if you are dealing with the acceleration of air I believe you need to pay more attention to the events surrounding the local collapses. I think he's assuming too much in favor of the result he desires.

Just my $.02

[Sizzler]

The calculation is for the global collapse. I have no problem with that. The issue is if you are dealing with the acceleration of air I believe you need to pay more attention to the events surrounding the local collapses. I think he's assuming too much in favor of the result he desires.

Just my $.02

Yes I understand what you mean. I thought about that too. Is it suggested that the "inside" of the building collapsed well before the "outer" part of the building? That would make the fall time of 6.5 irrelevant to the collapse of the inside (floors) part. Right (at least in laymam..haha)?

[DGM]

Yes I understand what you mean. I thought about that too. Is it suggested that the "inside" of the building collapsed well before the "outer" part of the building? That would make the fall time of 6.5 irrelevant to the collapse of the inside (floors) part. Right (at least in laymam..haha)?
Essentially yes.

The east and west penthouses were very large structures in of them-self. To suggest that they disappeared into the building with out major internal collapses in my opinion is absurd. I can't see how any calculations that don't include this phase of the collapse could be valid.

[aggle-rithm]

For some reason, I keep wondering why people would go to so much trouble to cover up the destruction of a building that was so badly damaged it would have had to be destroyed anyway.

[Sizzler]

Essentially yes.

The east and west penthouses were very large structures in of them-self. To suggest that they disappeared into the building with out major internal collapses in my opinion is absurd. I can't see how any calculations that don't include this phase of the collapse could be valid.


But isn't this what truthers say about the Bazant model? So if the Bazant model is a good simplified model, why isn't this one?

Any answer will go straight over my head. Perhaps I should just be a lurker here.:)

[DGM]

But isn't this what truthers say about the Bazant model? So if the Bazant model is a good simplified model, why isn't this one?

Any answer will go straight over my head. Perhaps I should just be a lurker here.:)
The issue is with the assumptions. In all models there are unavoidable assumptions made to compensate for the unknown. In the Bazant model the assumptions are all in favor of collapse arrest. This is the way it should be, in other words trying to disprove your own conclusions. In this case the assumptions are in favor of the concussion. Not correct method as far as I can see.

[GregoryUrich]

The calculation is for the global collapse. I have no problem with that. The issue is if you are dealing with the acceleration of air I believe you need to pay more attention to the events surrounding the local collapses. I think he's assuming too much in favor of the result he desires.

Just my $.02

What result is it that I desire?

If the inner structure failed significantly prior to the fall of the roof line, windows would have been blown out by the air pressure caused by floors falling.

[DGM]

What result is it that I desire?

If the inner structure failed significantly prior to the fall of the roof line, windows would have been blown out by the air pressure caused by floors falling.
I think you would be correct except for the fact that the building had large open gashes. This building was in no way air tight when the collapse began.

Hey I know that you don't ignore calculations and good engineering when you write your papers. I think that this paper will end up being revised and the results will reflect that. I do believe though at this point there is a bias toward collapse other than gravity. As I said this is my opinion.

[GregoryUrich]

The issue is with the assumptions. In all models there are unavoidable assumptions made to compensate for the unknown. In the Bazant model the assumptions are all in favor of collapse arrest. This is the way it should be, in other words trying to disprove your own conclusions. In this case the assumptions are in favor of the concussion. Not correct method as far as I can see.

Bazant had a few assumptions in favor of arrest and 9 assumptions in favor of collapse progression.

1. No energy absorbed elastically in upper block
2. Upper block weighed too much
3. No plastic energy during initial fall
4. Spring constant 10x realistic
5. No momentum transfer
6. Load capacity = design load
7. No adiabatic heating
8. No energy to expel air
9. No plastic energy for other damage

It turns out however that even when these factors are considered that collapse does progress. Or should I manipulate the assumptions to get the result I desire?

Even with Dr. Greenings assumptions for mass and PE. It still holds up.

[GregoryUrich]

I think you would be correct except for the fact that the building had large open gashes. This building was in no way air tight when the collapse began.

Hey I know that you don't ignore calculations and good engineering when you write your papers. I think that this paper will end up being revised and the results will reflect that. I do believe though at this point there is a bias toward collapse other than gravity. As I said this is my opinion.

We would have seen smoke expelled from windows which were already broken.

[DGM]

We would have seen smoke expelled from windows which were already broken.
Where did the penthouses (and everything inside them) go then?

I simply think that their disappearance into the roof line is too great of an event to be ignored. I find it hard to believe you don't seem to think this also.

[GregoryUrich]

For some reason, I keep wondering why people would go to so much trouble to cover up the destruction of a building that was so badly damaged it would have had to be destroyed anyway.

I have trouble with a convincing motive too. Maybe we are looking a huge design flaw or shoddy construction. However, regardless of design or construction, the structure should give significant resistance.

[SDC]

But isn't this what truthers say about the Bazant model? So if the Bazant model is a good simplified model, why isn't this one?

Any answer will go straight over my head. Perhaps I should just be a lurker here.:)

That's all I do when the engineers start talking among themselves. Best to stay out of their way.

[GregoryUrich]

Where did the penthouses (and everything inside them) go then?

I simply think that their disappearance into the roof line is too great of an event to be ignored. I find it hard to believe you don't seem to think this also.

The trading floor? :)

NIST suggests those events were related to failures lower in the building. If we suppose they were, a number of members and or connections failed. How many members and connections needed to be intact for the building to remain standing? Enough to support the weight anyway.

[DGM]

The trading floor? :)

NIST suggests those events were related to failures lower in the building. If we suppose they were, a number of members and or connections failed. How many members and connections needed to be intact for the building to remain standing? Enough to support the weight anyway.
Yes but only enough to hold the wall (or face) that we could see. I think a major issue with analyzing this collapse is the lack of vantage points that it was seen from. We simply don't know what was happening on the other side of the building. Was sections of windows blowing out? I don't know. Did it start to drop before the face we could see?

Simply put I think there are too many variables to assume the collapse time as far as determining the energy used from acceleration of air.

[Major_Tom]

From the point of view of questionable circumstances involved in the collapse of WTC 7, there are 3 points which strike many people as odd.

1) Fall time and resistance (which you are covering now)
2) A symmetrical fall straight downwards.
3) The very odd looking resultant pile of rubble.

Concerning #3, there is a good collection of photos, many of which you may not have seen before, available at the following link:

http://www.sharpprintinginc.com/911/index.php?module=photoalbum&PHPWS_Album_op=view&PHPWS_Album_id=11&MMN_position=138:138

I got these photos from a talented archivist who just recently made his collection public.


The 3 points above stand out to many people as "fishy".

Any help our engineers can give to clarify these points would be appreciated.

[GregoryUrich]

Yes but only enough to hold the wall (or face) that we could see. I think a major issue with analyzing this collapse is the lack of vantage points that it was seen from. We simply don't know what was happening on the other side of the building. Was sections of windows blowing out? I don't know. Did it start to drop before the face we could see?

Simply put I think there are too many variables to assume the collapse time as far as determining the energy used from acceleration of air.

So if the entire inside of the building fell down inside. What potential energy was left to drive out the air?

Do we see a jet of smoke and dust ejecting out of the top of the building where the penthouses were?

[Major_Tom]

A forth and final(?) issue would be how the fall seemed to be predicted.

The BBC thing was a bit odd.

[einsteen]

Gregory, just like the wtc you can find a relation between the collapse energy per floor and the mass per floor in two ways. Look at the acceleration of the drop, assume a "crush down", no pancaking needed and you find immediately the ratio between those values. The other option is to calculate the collapse time as function of the energy to destroy a story and the mass, it seems that this ratio could be fitted using a collapse time of 6.6 seconds. They should be the same of course. An other interesting thing is that if you assume that the collapse is complete (which was the case) there is also a upper value of the collapse time, I remember it was about 7.4 which means that it could never take 10 seconds for example. The drop of the penthouses is not part of the crush-down but part of pre-weakening activities.

[GlennB]

Where would the dust and smoke eject? At the damaged South side?
That the E Penthouse spent 6 or so seconds collapsing into the building prior to "global collapse" is undeniable.
That the structures previously supporting it must have failed to provoke this collapse is also (to my mind) also undeniable.
Therefore significant (some might say massive) interior damage was occuring for about 6 seconds prior to "global collapse".
That "global collapse" is always taken to mean the total collapse of the main structure - when all we actually see is the collapse of the N+W sides - might be of significance in any analysis you make.

[Sabrina]

Every photo I've seen of the north face of WTC7 (which, granted, aren't many, but they do exist; Aman Zafar's page has a few as well as some other places) had smoke literally pouring from what looked like the entire north facing facade. Video footage as I recall supports that as well; video from later in the day focused on WTC7 shows the smoke billowing from the building on all floors that are visible. That would seem to suggest that numerous windows were broken out on the north face and were obscured by the smoke in addition to the giant gashes in the facade of the building. When the penthouses fell in, the smoke and dust from debris already had a ready egress; it didn't need to billow largely from the top of the building, as it had the broken windows and huge gashes on the north face to exit from. I'd be interested in trying to note if there was a momentary increase in the smoke billowing from the building immediately subsequent to those penthouse collapses; I never paid much attention before, but this has piqued my interest. I'm going to try to find some videos in the archive to see if there's any evidence of that.

[Major_Tom]

Does anyone have a photo of the supposed 10 story gash in WTC 7, or is the only evidence eyewitness testimony?

I have photos of the walkway going over the street to WTC 7 that has no large WTC 1 debris on it at all (in the album mentioned a few posts ago). I also have a photo of the southwest corner (taken from the northwest so you can only see the west facade) that does not show a gash.

This leaves only a small space along the south face, on the west side, for the gash to occur. I am not seeing any signs of large debris making it over the street along the south facade of WTC 7.

[beachnut]

Big giant holes, broken windows. Let me see; closing the car door against air resistance with closed window, is more than with open windows. WTC7, open windows.

Major portions of WTC7 had fallen internally, and the unique design of WTC7 makes an amateur approach quite laughable.

The major smoking gun to find a no evidence truther is when they bring up WTC7. It means you have found someone with zero evidence just like the rest of 9/11 truth.

[aggle-rithm]

I have trouble with a convincing motive too. Maybe we are looking a huge design flaw or shoddy construction.

I'm voting huge design flaw...although it was really a systemic problem. Building codes had become too lax in New York, from what I've heard of more qualified people.

However, regardless of design or construction, the structure should give significant resistance.

It did. One of the tallest buildings in the world FELL ON IT. Not the entire mass, of course, but still...the fact that it didn't immediately collapse is testament to its significant resistance.

[aggle-rithm]

A forth and final(?) issue would be how the fall seemed to be predicted.

The BBC thing was a bit odd.

Not really. There have been many instances of a news organization jumping the gun and reporting something that was likely to happen but had not happened yet, or in fact never happened at all. Ever seen the "Dewey Defeats Truman" headlines? How about the network news anchor who reported James Brady dead after the Reagan shooting in 1981? Brady STILL hasn't died.

How about the reports on 9/11 that the State Department had been bombed? Do you think someone was SUPPOSED to bomb it, but forgot?

[aggle-rithm]

Does anyone have a photo of the supposed 10 story gash in WTC 7, or is the only evidence eyewitness testimony?

I have photos of the walkway going over the street to WTC 7 that has no large WTC 1 debris on it at all (in the album mentioned a few posts ago). I also have a photo of the southwest corner (taken from the northwest so you can only see the west facade) that does not show a gash.

This leaves only a small space along the south face, on the west side, for the gash to occur. I am not seeing any signs of large debris making it over the street along the south facade of WTC 7.




Funny, the damage doesn't look that bad from here...

[Pardalis]

Why is it so hard for some people to wait for the final report?

[Sabrina]

Possibly because NIST keeps promising it and keeps pushing the release date back.

I know I'm impatient for it and getting more and more irritated the longer it takes. But that's me personally.

[NobbyNobbs]

I used a bottom-up collapse.

I can't say I know much detail about this topic, but doesn't using a bottom-up collapse model presuppose the conclusion you are reaching? That is, by saying the collapse is bottom-up, aren't you already setting the conditions for a controlled demolition?

Then again, maybe my head is bottom-up. Please correct me if I'm wrong.

[DGM]

So if the entire inside of the building fell down inside. What potential energy was left to drive out the air?

Do we see a jet of smoke and dust ejecting out of the top of the building where the penthouses were?
If the whole building did collapse like that the air would stay where it is and the exterior walls would fall past it.:eek:

This is exactly what I'm referring too. I believe that with out pressurizing the air or having to move large volumes of air at great velocities the energy required would be quite low. Your calculations appear to be worst case (or best depending on how you look at it).

Now I admit I don't know exactly how to do the calculations to support my case but I do understand the principles and I believe my logic is sound. I do however encourage (and quite frankly hope) any of the resident engineers to point me in the correct direction if my thinking is in error.

[GregoryUrich]

I can't say I know much detail about this topic, but doesn't using a bottom-up collapse model presuppose the conclusion you are reaching? That is, by saying the collapse is bottom-up, aren't you already setting the conditions for a controlled demolition?

Then again, maybe my head is bottom-up. Please correct me if I'm wrong.

I use bottom-up because that's what is looks like. We know it wasn't top down. Anyway bottom up dissipates the least amount of energy and has the most energy available early in the collapse. If I was suggesting bottom-up for WTC1, you would have a valid point.

[Pardalis]

Possibly because NIST keeps promising it and keeps pushing the release date back.

I know I'm impatient for it and getting more and more irritated the longer it takes. But that's me personally.

I blame that on the internet generation.

Nobody waits anymore. The concept of "in due time" seems to be disappearing. ;)

[GregoryUrich]

If the whole building did collapse like that the air would stay where it is and the exterior walls would fall past it.:eek:

This is exactly what I'm referring too. I believe that with out pressurizing the air or having to move large volumes of air at great velocities the energy required would be quite low. Your calculations appear to be worst case (or best depending on how you look at it).

Now I admit I don't know exactly how to do the calculations to support my case but I do understand the principles and I believe my logic is sound. I do however encourage (and quite frankly hope) any of the resident engineers to point me in the correct direction if my thinking is in error.

I'm pretty sure you can see the roof in one of the collapse videos so at least some air would be forced out of the holes where the penthouses were. My point is and has been that it is not realistic to assume that there was significant collapse inside the building until the roof moved.

Also large volumes of air were moved as indicated by the the huge dust clouds spreading out from the bottom of the building.

[GregoryUrich]

I'm voting huge design flaw...although it was really a systemic problem. Building codes had become too lax in New York, from what I've heard of more qualified people.

It did. One of the tallest buildings in the world FELL ON IT. Not the entire mass, of course, but still...the fact that it didn't immediately collapse is testament to its significant resistance.

Significant resistance during the collapse. The building could and did hold itself up for quite a while after being damaged.

[GregoryUrich]

Big giant holes, broken windows. Let me see; closing the car door against air resistance with closed window, is more than with open windows. WTC7, open windows.

Major portions of WTC7 had fallen internally, and the unique design of WTC7 makes an amateur approach quite laughable.

The major smoking gun to find a no evidence truther is when they bring up WTC7. It means you have found someone with zero evidence just like the rest of 9/11 truth.

If you would have taken the time to try and understand my calculation instead of just giving your usual knee-jerk bunk, you would know that I calculate the resistance with no restrictions from windows or framing. I.e. totally open.

Please present your evidence that large portions had fallen internally.

[Sabrina]

Has anyone taken into account the fact that the damage was ongoing throughout the seven hours before WTC7 collapsed?

I can't help but notice that we all (myself included) seem to be concentrating solely on the collapse of WTC1 tearing a gigantic gash into the building, making that out to be the only damage; but fires were burning throughout the building for approximately seven hours, and NONE of them were ever really fought by firefighters. So isn't the damage much more difficult to model given that fire is more or less chaotic? It was perpetual damage, for lack of a better term, for seven straight hours. Without knowing a whole lot about building dynamics, I'm personally amazed the building stood as long as it did.

[GlennB]

...
My point is and has been that it is not realistic to assume that there was significant collapse inside the building until the roof moved.

For this assumption to be "realistic" we would have to assume that the fall of the E Penthouse was provoked by the failing of its support only at the roof level. This is speculation, of course, but it certainly doesn't appear "realistic". Why would the roof cave in with no lower damage?

Failure of core columns much lower in the building would appear to be a much more realistic proposition.

[Major_Tom]

Does anyone know where I can find the uncropped version of either of the 2 images shown below?

http://www.sharpprintinginc.com/911_old/Photo_archives/wtc_7/wtc7cornercomp2ahireswx4.jpg

The person who put this together is obviously using it to show that the image on the left is manipulated.

[DGM]

I'm pretty sure you can see the roof in one of the collapse videos so at least some air would be forced out of the holes where the penthouses were. My point is and has been that it is not realistic to assume that there was significant collapse inside the building until the roof moved.

Also large volumes of air were moved as indicated by the the huge dust clouds spreading out from the bottom of the building.
I don't believe there was any of the roof left.
When you look at the videos of the collapse and note the speed that the penthouses disappeared, (I know that mass would be important) where do you think the remains and contents would be at the moment (given the time difference) the roof* appeared to start moving. I'm picturing them well on the way to the basement.


* I think it's more likely what is seen in the videos is the top of the set-back.

[GregoryUrich]

Has anyone taken into account the fact that the damage was ongoing throughout the seven hours before WTC7 collapsed?

I can't help but notice that we all (myself included) seem to be concentrating solely on the collapse of WTC1 tearing a gigantic gash into the building, making that out to be the only damage; but fires were burning throughout the building for approximately seven hours, and NONE of them were ever really fought by firefighters. So isn't the damage much more difficult to model given that fire is more or less chaotic? It was perpetual damage, for lack of a better term, for seven straight hours. Without knowing a whole lot about building dynamics, I'm personally amazed the building stood as long as it did.

Whether it should or should not have fallen is not really the issue here. At the point in time at which global collapse initiated, the building had been supporting itself just up to that point. The problem is that the building went from just passing the point at which where it could no longer support itself to zero resistance immediately. This is just not how steel structures behave regardless of damage or heating.

[GlennB]

Please present your evidence that large portions had fallen internally.

Strangely, evidence beyond the observed collapse of the E Penthouse isn't required here. The only alternative is that the E Penthouse fell below the roofline and then immediately stopped. Given that the absence of support structures was the reason for its collapse, this is a patently absurd proposition. Therefore large portions must have fallen internally.

[DGM]

Whether it should or should not have fallen is not really the issue here. At the point in time at which global collapse initiated, the building had been supporting itself just up to that point. The problem is that the building went from just passing the point at which where it could no longer support itself to zero resistance immediately. This is just not how steel structures behave regardless of damage or heating.
Zero resistance?
I don't believe you (or anyone slse) have shown this.

[beachnut]

If you would have taken the time to try and understand my calculation instead of just giving your usual knee-jerk bunk, you would know that I calculate the resistance with no restrictions from windows or framing. I.e. totally open.

Please present your evidence that large portions had fallen internally.
The major smoking gun that proves you found a petition signing thinks they got evidence truther is bringing up anything to do with WTC7. When you they bring up WTC7, you have found someone with zero evidence to back up their blind, drank the Kool-Aid support of 9/11 truth.

Plus, your simple model does not take into account the unique design and loading of WTC7. The WTC7 is a smoking gun of a 9/11 truth member, who puts hearsay ahead of rational thought. The real truth is too hard for most truthers to find and understand.

[GlennB]

Whether it should or should not have fallen is not really the issue here. At the point in time at which global collapse initiated, the building had been supporting itself just up to that point. The problem is that the building went from just passing the point at which where it could no longer support itself to zero resistance immediately. This is just not how steel structures behave regardless of damage or heating.

I replied to this kind of point earlier, but you seem to have missed it.

What state was the entire building's core in at the point of so-called "global collapse" ? We have little idea really, as all the photographic evidence is from the N and N-W.

Given that the E Penthouse was falling into the building for some 6 seconds before "global collapse" then treating the building as essentially intact up to the point of "global collapse" is wholly unjustified.

[beachnut]

Whether it should or should not have fallen is not really the issue here. At the point in time at which global collapse initiated, the building had been supporting itself just up to that point. The problem is that the building went from just passing the point at which where it could no longer support itself to zero resistance immediately. This is just not how steel structures behave regardless of damage or heating.
You have ignored the initial collapse of the Penthouse into the interior of WTC7. One simple post showing your superficial understanding of the WTC7 structure.

Things do all of a sudden collapse! Some times fast, sometimes slow. Why do we have to suffer thought your learning curve on WTC7 due to your lack of experience?

[GregoryUrich]

For this assumption to be "realistic" we would have to assume that the fall of the E Penthouse was provoked by the failing of its support only at the roof level. This is speculation, of course, but it certainly doesn't appear "realistic". Why would the roof cave in with no lower damage?

Failure of core columns much lower in the building would appear to be a much more realistic proposition.

Did the whole roof cave in?

Here (http://911research.wtc7.net/wtc/evidence/videos/wtc7_collapse2.html) and here (http://www.911research.com/wtc/evidence/videos/docs/wtc_7_cbs.mpg) you can see that the west penthouse dropped nearly simultaneously (if not simultaneously) with the roof.

I noticed that it does appear that smoke is expelled where the east penthouse used to be. Nonetheless most smoke and dust are expelled lower down which I interpret as evidence of where the floor by floor collapses are taking place. This still (http://s56.photobucket.com/albums/g171/boloboffin2/911/?action=view&current=WTC7lean.jpg) illustrates this point whereas there are small streams coming out of some windows due to backpressure, the large majority of dust and smoke is coming from low down and billowing upwards.

[GregoryUrich]

I replied to this kind of point earlier, but you seem to have missed it.

What state was the entire building's core in at the point of so-called "global collapse" ? We have little idea really, as all the photographic evidence is from the N and N-W.

Given that the E Penthouse was falling into the building for some 6 seconds before "global collapse" then treating the building as essentially intact up to the point of "global collapse" is wholly unjustified.

I don't think we need to know the state of the core. The building is not essentially intact. It is in the process of failing. It is however holding itself up which requires a certain amount of strength. This strength cannot suddenly disappear and provide no further resistance to collapse.

[DGM]

Did the whole roof cave in?

Here (http://911research.wtc7.net/wtc/evidence/videos/wtc7_collapse2.html) and here (http://www.911research.com/wtc/evidence/videos/docs/wtc_7_cbs.mpg) you can see that the west penthouse dropped nearly simultaneously (if not simultaneously) with the roof.

I noticed that it does appear that smoke is expelled where the east penthouse used to be. Nonetheless most smoke and dust are expelled lower down which I interpret as evidence of where the floor by floor collapses are taking place. This still (http://s56.photobucket.com/albums/g171/boloboffin2/911/?action=view&current=WTC7lean.jpg) illustrates this point whereas there are small streams coming out of some windows due to backpressure, the large majority of dust and smoke is coming from low down and billowing upwards.
The second video shows it quickly disappearing about 6 to 7 seconds before the roof line. Please watch that video and think about the speed of movement of that penthouse. Do you think it stopped just after it disappeared from view?


ETA I should have specified west penthouse.

[GregoryUrich]

The major smoking gun that proves you found a petition signing thinks they got evidence truther is bringing up anything to do with WTC7. When you they bring up WTC7, you have found someone with zero evidence to back up their blind, drank the Kool-Aid support of 9/11 truth.

Plus, your simple model does not take into account the unique design and loading of WTC7. The WTC7 is a smoking gun of a 9/11 truth member, who puts hearsay ahead of rational thought. The real truth is too hard for most truthers to find and understand.

I show you where you are wrong and you resort to insults.

I ask you to support your claim and you do not answer.

Where is the evidence that large portions had fallen internally?

[GregoryUrich]

The second video shows it quickly disappearing about 6 to 7 seconds before the roof line. Please watch that video and think about the speed of movement of that penthouse. Do you think it stopped just after it disappeared from view?

That's the east penthouse. Roughly 8 m/s before it disappears. There was clearly localised failure. If there was global failure, the roof would start to move.

[DGM]

That's the east penthouse. Roughly 8 m/s before it disappears. There was clearly localised failure. If there was global failure, the roof would start to move.
So what happened to it? This is a very large structure that started to move 6 or 7 seconds before any thing else we could see. This is a problem that needs to be addressed before any discussion of "global collapse". That structure was disappearing very quickly and would be unlikely to stop.

[CurtC]

This strength cannot suddenly disappear and provide no further resistance to collapse.

You must not have seen the video of the bridge collapse in Minnesota last summer. One second it's there with cars driving over it, the next second it's free-falling into the Mississippi.

[SDC]

GregoryUrich, you have some credibility when you provide calculations. But now you seem to have moved to, "Well, this is how it looked." That destroys your (and anyone's) credibility; reliance on the human eye... And unless you are trained in this area, that is a weak reed. It makes your comments no more useful than those of Major Tom, for example.

[NobbyNobbs]

This strength cannot suddenly disappear and provide no further resistance to collapse.


Why not?


Whether it should or should not have fallen is not really the issue here. At the point in time at which global collapse initiated, the building had been supporting itself just up to that point. The problem is that the building went from just passing the point at which where it could no longer support itself to zero resistance immediately. This is just not how steel structures behave regardless of damage or heating.

Are you suggesting it should have fallen in slow motion, or something?

Reminds me of a movie....


Dr. Dolen: Funny old bird.
Fletch: Is she ever. I've got some stories.
Dr. Dolen: I'll bet. Shame about Ed.
Fletch (vamping): It was. Really a shame. To go so suddenly.
Dr. Dolen: Oh, he was dying for years.
Fletch: Sure, but the end was so sudden.
Dr. Dolen: He was in intensive care for eight weeks.
Fletch: Yes, but the very end, when he actually died, that was extremely sudden.

[GregoryUrich]

GregoryUrich, you have some credibility when you provide calculations. But now you seem to have moved to, "Well, this is how it looked." That destroys your (and anyone's) credibility; reliance on the human eye... And unless you are trained in this area, that is a weak reed. It makes your comments no more useful than those of Major Tom, for example.

We are looking at videos and photos which are evidence. You seem convinced that the inside collapsed based on that we can "see" the east penthouse collapsing. We can't see what's happening in the building. At least I'm talking about stuff I can see.

[Major_Tom]

SDC, I didn't provide an opinion. I pointed out the sticking points many people would naturally have with the fall of WTC 7.

I provided a photo library and asked if anyone has the originals of the following 2 images. That's all.

http://www.sharpprintinginc.com/911_old/Photo_archives/wtc_7/wtc7cornercomp2ahireswx4.jpg

One of these 2 images is a fake. Someone has tried to lie to us. This is a fact and not an opinion.

Given the original images we can learn which one is a fake.

Why is this information useless?

[GregoryUrich]

So what happened to it? This is a very large structure that started to move 6 or 7 seconds before any thing else we could see. This is a problem that needs to be addressed before any discussion of "global collapse". That structure was disappearing very quickly and would be unlikely to stop.

Mackey and Dr. Greening have already discussed the energy issues somewhat on another thread. This issue was not the first one they thought of. If they show up here we'll see what they say. I don't think it's an issue. You are entitled to your opinion.

[beachnut]

You must not have seen the video of the bridge collapse in Minnesota last summer. One second it's there with cars driving over it, the next second it's free-falling into the Mississippi.
That can not happen in the fantasy world of 9/11 truth.
Examples, using facts, can only ruin the fantasy of making it up yourself.

Nothing ever fails in the world of 9/11 truth unless it was done by some NWO bush/clinton cabal of keebler elves.

[GregoryUrich]

SDC, I didn't provide an opinion. I pointed out the sticking points many people would naturally have with the fall of WTC 7.

I provided a photo library and asked if anyone has the originals of the following 2 images. That's all.

http://www.sharpprintinginc.com/911_old/Photo_archives/wtc_7/wtc7cornercomp2ahireswx4.jpg

One of these 2 images is a fake. Someone has tried to lie to us. This is a fact and not an opinion.

Given the original images we can learn which one is a fake.

Why is this information useless?

Good point MT. I didn't see what you were getting at before. I dare say that "it looks like" the photos have different damage.

[GregoryUrich]

Why not?

Are you suggesting it should have fallen in slow motion, or something?

Reminds me of a movie....

Dr. Rosenpxnis, I presume. WTC1 dissipated nearly 60% of the PE on resistance. WTC7 dissipated 15%. Sure they were different buildings, but as I believe I have the 15% is only the energy required to expel the air. Do you honestly believe the structure itself should provide no resistance.

[GregoryUrich]

Zero resistance?
I don't believe you (or anyone slse) have shown this.

That's what the calculations show.

[GlennB]

Did the whole roof cave in?

Here (http://911research.wtc7.net/wtc/evidence/videos/wtc7_collapse2.html) and here (http://www.911research.com/wtc/evidence/videos/docs/wtc_7_cbs.mpg) you can see that the west penthouse dropped nearly simultaneously (if not simultaneously) with the roof.



The size of the E Penthouse is clear in this photo. That much at least caved in.

http://i250.photobucket.com/albums/gg274/sap-guy/WTC7Epenthouseclearphoto.jpg

[Mancman]

We are looking at videos and photos which are evidence. You seem convinced that the inside collapsed based on that we can "see" the east penthouse collapsing. We can't see what's happening in the building. At least I'm talking about stuff I can see.

The east penthouse collapse must have caused internal damage.

See here: http://www.youtube.com/watch?v=Y5_e5yROoqY

Beneath the penthouse we see a shockwave travel to ground level, the building bulges and flexes, then global collapse ensues.

[GregoryUrich]

The east penthouse collapse must have caused internal damage.

See here: http://www.youtube.com/watch?v=Y5_e5yROoqY

Beneath the penthouse we see a shockwave travel to ground level, the building bulges and flexes, then global collapse ensues.

Thanks for that Mancman. I think you prove my point. I agree you can see the building flex and rebound. It would look much different if the mass if the penthouse went falling through the building and floors fell because the windows would get blown out.

[Mancman]

Thanks for that Mancman. I think you prove my point. I agree you can see the building flex and rebound. It would look much different if the mass if the penthouse went falling through the building and floors fell because the windows would get blown out.

So what do you think causes the flex which travels downwards directly below the penthouse?

[DGM]

Thanks for that Mancman. I think you prove my point. I agree you can see the building flex and rebound. It would look much different if the mass if the penthouse went falling through the building and floors fell because the windows would get blown out.
One thing you also notice in that video is the lack of significant air movement. Could the building have been so badly fractured inside as to let the majority of the air stay put?:eek:

[Norseman]

SDC, I didn't provide an opinion. I pointed out the sticking points many people would naturally have with the fall of WTC 7.

I provided a photo library and asked if anyone has the originals of the following 2 images. That's all.

http://www.sharpprintinginc.com/911_old/Photo_archives/wtc_7/wtc7cornercomp2ahireswx4.jpg

One of these 2 images is a fake. Someone has tried to lie to us. This is a fact and not an opinion.

Given the original images we can learn which one is a fake.

Why is this information useless?

Both images are genuine. I debated this in great detail with Christopher7 last year here (http://forums.randi.org/showthread.php?postid=2996595#post2996595) (post #3673) and on the following pages including post #3751 in that thread.

You will find the photo on the left hand side in NIST interim report (http://wtc.nist.gov/progress_report_june04/appendixl.pdf) on WTC 7. And the photo on right hand side you will find here, it is the last one before the night shots at the bottom of the page:
http://www.amanzafar.com/WTC/index.shtm

For some real good examples on light refraction effects look at the photos on page 66 and 63 (PDF page 78 and 76) in the report on One Meridian Plaza fire (http://www.usfa.dhs.gov/downloads/pdf/publications/tr-049.pdf).

That's it from me on this issue.

[Norseman]

Every photo I've seen of the north face of WTC7 (which, granted, aren't many, but they do exist; Aman Zafar's page has a few as well as some other places) had smoke literally pouring from what looked like the entire north facing facade. Video footage as I recall supports that as well; video from later in the day focused on WTC7 shows the smoke billowing from the building on all floors that are visible. That would seem to suggest that numerous windows were broken out on the north face and were obscured by the smoke in addition to the giant gashes in the facade of the building. When the penthouses fell in, the smoke and dust from debris already had a ready egress; it didn't need to billow largely from the top of the building, as it had the broken windows and huge gashes on the north face to exit from. I'd be interested in trying to note if there was a momentary increase in the smoke billowing from the building immediately subsequent to those penthouse collapses; I never paid much attention before, but this has piqued my interest. I'm going to try to find some videos in the archive to see if there's any evidence of that.

I assume you meant the the south face of WTC 7 and not the north face here, since the north face was undamaged after the collapse of WTC 1. Just a friendly correction from me.:)

[Sabrina]

Right; sorry, south face. My bad.

[jaydeehess]

The worst problem is that we cannot see the lowest floors of the north or south side.

(BTW Sabrina, its the south side that faced the towers and had many broken windows.)

The east penthouse falls due to failure of one or more columns directly under it. The debris from this crushes through the building and impacts the heavy trusses at the 5 and 7th floors. This reduces the strength of the core system, those heavy trusses are there for a reason. The northern core columns support the heavy beams over the pre-existing Con-ed building and cantilever the north facade.

Fail those core columns and the entire north half of the building will be falling on top of the Con-ed building which would be akin to a person stepping on an egg carton. The south half of the building had already suufered some significant damage to the perimeter system and had little to arrest a fall if the core was damaged at the 5th to 7th level. That would mean that the entire structure would essentially fall 7 floors with very little to arrest that fall. After falling that distance the impact with the ground would essentially shatter the structure.

I believe that there was one witness that described the lower north wall as pushing out just as global collapse started. That would be consistent with those beams over the Con-ed building losing their core support.

Was this a design flaw? Perhaps, in that the initiating event would seem to have been the result of the office fires going un-fought and causing a local column failure. However would the designers ever have considered a fire that would go on unfought for so long? Would the designers have ever considered what the effect of large parts of WTC 1 falling on it? Probably not.

[R.Mackey]

I want to discuss two different topics, namely the air pressurization, and the effective strength of the remaining structure. Let me also say that some of the slings and arrows aimed at Gregory appear unearned. There is an opportunity to learn from this, guys.

---

1. Air Pressurization

The question of energy spent expelling the air is not simple. Consider the following: In an ideal, inviscid fluid, there is actually no resistance offered by the air in this situation! How can this be?

Think of the question like this: We have air that is initially moving with the building, passes through a constriction, and ends up in free space. What velocity do we use for the air? Do we use it at the constriction? No, we don't. That instantaneous velocity of air is much higher than the bulk velocity, but it's a temporary cost. Air gets pushed through the constriction by the much slower air behind it, and it expands into a space left by the external air, which is moving too. And there's no cost to start the bulk air moving, because it falls with the structure -- we've already accounted for its potential energy. So, had our structure been filled with superfluid helium, the fluid resistance would be zero. There would be no effective backpressure inside the structure.

Of course, we are not dealing with superfluid helium. What happens with a real fluid is known as the Venturi Effect (http://en.wikipedia.org/wiki/Venturi_effect). The fluid only gets free acceleration through the constriction until it runs out of ambient pressure to accelerate it. This pressure energy gets returned immediately outside the restriction, but since the pressure is finite, there's a finite amount of acceleration it can handle. Once we exceed this -- and we will -- we enter a blocked flow condition.

When the flow is blocked at the restriction, it will cause a backpressure inside the structure, and this backpressure will indeed oppose the collapse. The rising backpressure means additional pressure to oppose the Venturi Effect, so flow increases until pressure and flow rate balance. We can then estimate the energy loss during collapse -- because (most of) this energy returns once the air has left the structure -- either from the Bernoulli energy density at the restriction, or the adiabatic gas energy contained in the pressurized region.

Solving this rigorously depends strongly on the size and location of the restrictions. And there's yet another issue, namely that the structure can only handle a small amount of backpressure before ruptures start appearing all over. How much? Only a couple of PSI -- anything more will surely break windows upstairs, and may crack or even burst damaged walls and floors. So we can put a very rough upper limit on the opposing force, and from that the total energy expended against the gas, by assuming say 10 kPa backpressure times the floor area, integrated over the height of the structure, which works out to about 7.7 GJ.

This number is actually in decent agreement with Gregory's figure -- my calculation could easily be off by a factor of two or three in either direction. Working out the correct answer will be difficult.

I speculate that the actual number is closer to mine or even less, simply because the condition of the building was very poor. Fires had broken windows on over ten floors. The structure had ventilation to begin with. There were large elevator shafts running the height of the building, and we know the roof experienced substantial collapses prior to the rest of the structure. Thus, there were many escape paths for overpressure, and perhaps it could only handle 0.5 PSI or thereabouts? Who knows.

Nonetheless, Gregory's number is plausible.


2. "Resistance Factor"

Regarding the remaining strength of the building, what you've done here is basically confirmed the result of Dr. Heikki Kurttila (http://www.saunalahti.fi/wtc2001/WTC7_collapse_examination.pdf). Like you, he estimated that the surviving structure resisted the collapse with an average force equal to only 16% of the pre-collapse weight.

I explored this in Appendix B of my whitepaper. Basically, the mathematical result is correct, but the interpretation is not. Quoting from my whitepaper:

Dr. Kurttila, on the other hand, is not estimating the total energy – he is attempting to estimate the peak force. He wants to know what the strength of the building is, and extract this strength from observation of the collapse time. Unfortunately, the strength is a static quantity, not a dynamic quantity. Dr. Kurttila estimates (for WTC 7, not the Towers) that the “resistance factor,” i.e. the fraction of resistance similar to our computation above, is about 16%, and concludes that this number is “too low.”

He is in no position to draw this conclusion. Suppose, for instance, the structure – even damaged and during collapse – was capable of supporting twice the static load, which we will call Fstatic, but that it could only do so until being deflected by 25 cm. After this, any given floor will snap, and the resistance goes to zero until the next floor is hit 300 cm below. Work, again, is force times distance. The total work done on any given floor would be 2 Fstatic x 25 cm + 0 x 300 cm = 50 Fstatic cm. If we model the structure as homogeneous, supplying instead an average force called Fdynamic that acts over the full 325 cm distance of each floor, we can estimate this average force by dividing the total work by the total distance. The total work done in both situations must be the same. Therefore, we can calculate Fdynamic = 50 Fstatic cm / 325 cm = 0.15 Fstatic, what Dr. Kurttila would call a “resistance factor” of 0.15, very close to his estimate for WTC 7.

In other words, the structure is not very flexible. The total energy dissipated -- the total work done by the structure -- is the product of the resisting force times the distance over which it resists. Because it isn't flexible, the distances are actually very small. Therefore, the collapse is really a series of brief jerks and snapthroughs, and if you average this out over the entire duration of the collapse, you will indeed get a low number compared to the ultimate static strength of the building prior to collapse.


3. Energy Comparison

Does this make sense? Could it be true that the energy to displace the air is comparable to or even greater than that to smash the building?

Why, yes, actually. It's counterintuitive, but it is possible. Two points to consider:

First, above we spoke of pressurizing the building to 1 PSI or so during the collapse. 1 PSI is 144 pounds per square foot, and that is actually comparable to the strength of the building! (About half of the ultimate load on a given floor, roughly). Also, unlike the structure, this really is a continuous opposing force, not one that goes to zero every time a new set of columns gives way. Integrated over the whole collapse, this is indeed competitive.

Second, we're not quite comparing the same things here. The air displacement is all the energy the air is ever going to get. We're considering the full kinetic energy of the air. In contrast, the energy expended on the structure during collapse is only part of it. There will still be a considerable amount of energy left over, in the form of kinetic energy after local failure, that continues to grind the pieces together at the ground.

Thus, it is indeed possible for the air to absorb more energy than the structure itself during collapse. This result will probably surprise a lot of people! But this is why it's important to trust in your calculations, and not shoot the messenger. There's a lesson in there for the JREF stalwarts.


4. Comparison to WTC 1 and 2

Also from Appendix B of my whitepaper, I estimate that the Towers absorbed closer to 50% of their gravitational energy as they collapsed, compared to only 16% in WTC 7. Why?

The answer is in the style of collapse. WTC 1 and 2 both experienced a top-down progressive collapse, whereas WTC 7 was more bottom-up. In WTC 1 and 2, the structure is really no more able to oppose the collapse through sheer strength, but instead, you have the contact plane way up in the air, and that means momentum transfer. In addition to breaking columns, the descending mass also has to overcome the inertia of the lower block. As it does so, it expends more energy, which means more total destruction of things like concrete floors.

WTC 7, on the other hand, has the contact interface at or near ground level. Momentum transfer is to the Earth, and so rather than slow down the descending "upper block," it merely destroys everything at the ground level all at once. None of the Earth's inertia gets transmitted up. As a result, the "momentum sink" of WTC 1 and 2 just doesn't happen.

Similarly, there is less energy expenditure high in the structure. This is why we don't see concrete comminution or drywall devastation in the same degree.

Regarding destruction of materials, it is also important to note that the gravitational potential energy per kilogram, or per square meter, will be much lower in WTC 7 than in the Towers. Thus, we predict a less thorough destruction of material, and this is indeed exactly what we see.


5. Closing Comments

I want to stress again that this kind of calculation is fraught with uncertainties, and therefore this is really not a good way to estimate the building properties. However, after some consideration, I don't see anything in GregoryUrich's calculation that appears implausible. I speculate that his results might be a tad high, but he's got the right order of magnitude.

Consideration of this problem, even using greatly simplified models and rough numbers, actually exposes some features of mechanics that are not obvious at first glance. This is a useful exercise. This also highlights the peril in arguing from common sense. We just don't have experience with these kinds of events in our daily lives.

I see no reason now or before to suspect explosives were involved. This should have been obvious -- Chief Nigro can tell you that WTC 7 was coming down, explosives or no explosives, so what's the point? Just to make it fall faster? Nonsense. Neither did Gregory suggest this, to his credit. This is just what happens when tall buildings exceed their limits.

[Tweeter]

easier cleanup

[R.Mackey]

Bazant had a few assumptions in favor of arrest and 9 assumptions in favor of collapse progression.

1. No energy absorbed elastically in upper block
2. Upper block weighed too much
3. No plastic energy during initial fall
4. Spring constant 10x realistic
5. No momentum transfer
6. Load capacity = design load
7. No adiabatic heating
8. No energy to expel air
9. No plastic energy for other damage

It turns out however that even when these factors are considered that collapse does progress. Or should I manipulate the assumptions to get the result I desire?

Even with Dr. Greenings assumptions for mass and PE. It still holds up.

Bazant & Zhou does treat momentum transfer and plastic energy. Their load capacity is a bit flaky, weight distribution and total is too simple, spring constant debatable, and no heating etc., but correcting these factors only eats into the gross overload they predict, and does not lead to an expectation of arrest.

BLBG treats all of these issues. Mass is still arguably high, but it will divide out, as we've discussed several times.

[GregoryUrich]

I want to discuss two different topics, namely the air pressurization, and the effective strength of the remaining structure. Let me also say that some of the slings and arrows aimed at Gregory appear unearned. There is an opportunity to learn from this, guys.

---

1. Air Pressurization

The question of energy spent expelling the air is not simple. Consider the following: In an ideal, inviscid fluid, there is actually no resistance offered by the air in this situation! How can this be?

Think of the question like this: We have air that is initially moving with the building, passes through a constriction, and ends up in free space. What velocity do we use for the air? Do we use it at the constriction? No, we don't. That instantaneous velocity of air is much higher than the bulk velocity, but it's a temporary cost. Air gets pushed through the constriction by the much slower air behind it, and it expands into a space left by the external air, which is moving too. And there's no cost to start the bulk air moving, because it falls with the structure -- we've already accounted for its potential energy. So, had our structure been filled with superfluid helium, the fluid resistance would be zero. There would be no effective backpressure inside the structure.

Of course, we are not dealing with superfluid helium. What happens with a real fluid is known as the Venturi Effect (http://en.wikipedia.org/wiki/Venturi_effect). The fluid only gets free acceleration through the constriction until it runs out of ambient pressure to accelerate it. This pressure energy gets returned immediately outside the restriction, but since the pressure is finite, there's a finite amount of acceleration it can handle. Once we exceed this -- and we will -- we enter a blocked flow condition.

When the flow is blocked at the restriction, it will cause a backpressure inside the structure, and this backpressure will indeed oppose the collapse. The rising backpressure means additional pressure to oppose the Venturi Effect, so flow increases until pressure and flow rate balance. We can then estimate the energy loss during collapse -- because (most of) this energy returns once the air has left the structure -- either from the Bernoulli energy density at the restriction, or the adiabatic gas energy contained in the pressurized region.

Solving this rigorously depends strongly on the size and location of the restrictions. And there's yet another issue, namely that the structure can only handle a small amount of backpressure before ruptures start appearing all over. How much? Only a couple of PSI -- anything more will surely break windows upstairs, and may crack or even burst damaged walls and floors. So we can put a very rough upper limit on the opposing force, and from that the total energy expended against the gas, by assuming say 10 kPa backpressure times the floor area, integrated over the height of the structure, which works out to about 7.7 GJ.

This number is actually in decent agreement with Gregory's figure -- my calculation could easily be off by a factor of two or three in either direction. Working out the correct answer will be difficult.

I speculate that the actual number is closer to mine or even less, simply because the condition of the building was very poor. Fires had broken windows on over ten floors. The structure had ventilation to begin with. There were large elevator shafts running the height of the building, and we know the roof experienced substantial collapses prior to the rest of the structure. Thus, there were many escape paths for overpressure, and perhaps it could only handle 0.5 PSI or thereabouts? Who knows.

Nonetheless, Gregory's number is plausible.


2. "Resistance Factor"

Regarding the remaining strength of the building, what you've done here is basically confirmed the result of Dr. Heikki Kurttila (http://www.saunalahti.fi/wtc2001/WTC7_collapse_examination.pdf). Like you, he estimated that the surviving structure resisted the collapse with an average force equal to only 16% of the pre-collapse weight.

I explored this in Appendix B of my whitepaper. Basically, the mathematical result is correct, but the interpretation is not. Quoting from my whitepaper:



In other words, the structure is not very flexible. The total energy dissipated -- the total work done by the structure -- is the product of the resisting force times the distance over which it resists. Because it isn't flexible, the distances are actually very small. Therefore, the collapse is really a series of brief jerks and snapthroughs, and if you average this out over the entire duration of the collapse, you will indeed get a low number compared to the ultimate static strength of the building prior to collapse.


3. Energy Comparison

Does this make sense? Could it be true that the energy to displace the air is comparable to or even greater than that to smash the building?

Why, yes, actually. It's counterintuitive, but it is possible. Two points to consider:

First, above we spoke of pressurizing the building to 1 PSI or so during the collapse. 1 PSI is 144 pounds per square foot, and that is actually comparable to the strength of the building! (About half of the ultimate load on a given floor, roughly). Also, unlike the structure, this really is a continuous opposing force, not one that goes to zero every time a new set of columns gives way. Integrated over the whole collapse, this is indeed competitive.

Second, we're not quite comparing the same things here. The air displacement is all the energy the air is ever going to get. We're considering the full kinetic energy of the air. In contrast, the energy expended on the structure during collapse is only part of it. There will still be a considerable amount of energy left over, in the form of kinetic energy after local failure, that continues to grind the pieces together at the ground.

Thus, it is indeed possible for the air to absorb more energy than the structure itself during collapse. This result will probably surprise a lot of people! But this is why it's important to trust in your calculations, and not shoot the messenger. There's a lesson in there for the JREF stalwarts.


4. Comparison to WTC 1 and 2

Also from Appendix B of my whitepaper, I estimate that the Towers absorbed closer to 50% of their gravitational energy as they collapsed, compared to only 16% in WTC 7. Why?

The answer is in the style of collapse. WTC 1 and 2 both experienced a top-down progressive collapse, whereas WTC 7 was more bottom-up. In WTC 1 and 2, the structure is really no more able to oppose the collapse through sheer strength, but instead, you have the contact plane way up in the air, and that means momentum transfer. In addition to breaking columns, the descending mass also has to overcome the inertia of the lower block. As it does so, it expends more energy, which means more total destruction of things like concrete floors.

WTC 7, on the other hand, has the contact interface at or near ground level. Momentum transfer is to the Earth, and so rather than slow down the descending "upper block," it merely destroys everything at the ground level all at once. None of the Earth's inertia gets transmitted up. As a result, the "momentum sink" of WTC 1 and 2 just doesn't happen.

Similarly, there is less energy expenditure high in the structure. This is why we don't see concrete comminution or drywall devastation in the same degree.

Regarding destruction of materials, it is also important to note that the gravitational potential energy per kilogram, or per square meter, will be much lower in WTC 7 than in the Towers. Thus, we predict a less thorough destruction of material, and this is indeed exactly what we see.


5. Closing Comments

I want to stress again that this kind of calculation is fraught with uncertainties, and therefore this is really not a good way to estimate the building properties. However, after some consideration, I don't see anything in GregoryUrich's calculation that appears implausible. I speculate that his results might be a tad high, but he's got the right order of magnitude.

Consideration of this problem, even using greatly simplified models and rough numbers, actually exposes some features of mechanics that are not obvious at first glance. This is a useful exercise. This also highlights the peril in arguing from common sense. We just don't have experience with these kinds of events in our daily lives.

I see no reason now or before to suspect explosives were involved. This should have been obvious -- Chief Nigro can tell you that WTC 7 was coming down, explosives or no explosives, so what's the point? Just to make it fall faster? Nonsense. Neither did Gregory suggest this, to his credit. This is just what happens when tall buildings exceed their limits.

Thanks for your thoughtful response. I'm not sure I'll get a chance to think through your comments until this weekend. I just wanted to mention that as I was dosing off last night I realised that the shape of the building makes a significant difference. I think my result for air resistance will be revised downward by 40-50%.

[GregoryUrich]

The worst problem is that we cannot see the lowest floors of the north or south side.

(BTW Sabrina, its the south side that faced the towers and had many broken windows.)

The east penthouse falls due to failure of one or more columns directly under it. The debris from this crushes through the building and impacts the heavy trusses at the 5 and 7th floors. This reduces the strength of the core system, those heavy trusses are there for a reason. The northern core columns support the heavy beams over the pre-existing Con-ed building and cantilever the north facade.

Fail those core columns and the entire north half of the building will be falling on top of the Con-ed building which would be akin to a person stepping on an egg carton. The south half of the building had already suufered some significant damage to the perimeter system and had little to arrest a fall if the core was damaged at the 5th to 7th level. That would mean that the entire structure would essentially fall 7 floors with very little to arrest that fall. After falling that distance the impact with the ground would essentially shatter the structure.

I believe that there was one witness that described the lower north wall as pushing out just as global collapse started. That would be consistent with those beams over the Con-ed building losing their core support.

Was this a design flaw? Perhaps, in that the initiating event would seem to have been the result of the office fires going un-fought and causing a local column failure. However would the designers ever have considered a fire that would go on unfought for so long? Would the designers have ever considered what the effect of large parts of WTC 1 falling on it? Probably not.

If the east penthouse "crushes" through the building, how long will it take to get to the 7th floor? I think a momentum/energy calc will show that it can't reach the 7th floor in 6-7 seconds.

[GregoryUrich]

One thing you also notice in that video is the lack of significant air movement. Could the building have been so badly fractured inside as to let the majority of the air stay put?:eek:

I'm not sure I understand what you mean. Could you expand?

[beachnut]

If the east penthouse "crushes" through the building, how long will it take to get to the 7th floor? I think a momentum/energy calc will show that it can't reach the 7th floor in 6-7 seconds.
What? You have zero idea how strong the building is at 5 pm after burning all day. The building was on fire all day and that fire was not fought. You will have zero ability to apply any steel strength at the time WTC7 fails to stand due to fire and damage. There is no survival for buildings that burn and are not fought like WTC7. Please present a building, and office building that burned all day and did not have structural failure. Have you even researched WTC7; I have to say no, since your posts reflect no insight into anything about WTC7.

Your Quixotic attack lacks a knowledge of structures, and you seem to lack any experience on anything about 9/11 until you are guided by people here at JREF. Each time you come up with a new thesis, the work is done by JREF by critiquing you to correctness. Just look back to each of your projects and attempt to support 9/11 truth's lies and false information.

The more you post the more it becomes clear you lack knowledge on 9/11 issues until people, even lay people, guide your research and correct your errors. Between your brief successes at understanding, you display total lack of knowledge (you even mention PNAC, a true flag for someone who lacks fundamental knowledge on 9/11) on each new endeavor to save the 9/11 truth movement form total implosion which actually occurred 6 years ago, pre-debunked on 9/11. Does anyone in 9/11 truth study 9/11 before making all the false statements and made up theories that lack evidence?

Please study WTC7 before you post more junk and have to learn on the post, so your veiled scientific approach resembles an attempt by the engineer you claim to be. If you do not study first, you will do more damage to the prestige of being called an Electrical Engineer; you need to be more supportive of our shared degree and at least appear more knowledgeable on WTC7 even though your conclusion is wrong before you started (yes, everyone knows you have signed the petition of 9/11 truth before having real evidence, the best you can do is mention PNAC, to support the hearsay conclusion of 9/11 truth; so, yes your conclusion is known even if you want to hide behind your shallow research, as if you are really trying to find the truth, which 9/11 TM has never even got close to doing).

I can't wait to see if you think it was silent RDX, or thermite. Please study first so you look better than the no plane guys, and beam weapon dustification experts.

[Tweeter]

I`m thinking beachnut must of stayed at a Holiday Inn Express last night.

[DGM]

I'm not sure I understand what you mean. Could you expand?
I'll try::)
Back in the original thread R.Mackey commented on the pressure and velocity of the air as being determining factors in the energy absorbed (if that's the right word). During those videos you don't see large releases of air through windows or large events that appear to be areas of overpressure. I guess my comment is more along the lines of the building being broken up enough as to not allow much pressure build up.

I too want to take some time to re-look at your calculations after I have a chance to let R.Mackey's post sink in.

[CurtC]

I'm not sure I understand what you mean. Could you expand?
I think DGM was considering the idea that maybe when the penthouse fell into the building, it didn't have to push air out of the building, and instead just moved around the air that was already contained in the building.

Instead of a piston in a cylinder analogy, think of dropping a brick into a bucket.

[jaydeehess]

If the east penthouse "crushes" through the building, how long will it take to get to the 7th floor? I think a momentum/energy calc will show that it can't reach the 7th floor in 6-7 seconds.

Inprecise choice of wording on my part.

there would be no momentum transfer if it does not hit anything on the way down.

The east penthouse fell in due to some damage occuring well donw in the building. The load could not be supported by the columns that failed. The equipment that then fell was doing so into a space that had relatively little to stop its desent since anything in that path had already collapsed or at least started moving before the penthouse debris did.

Assuming though that the core structure west of that location and the system of load transfer members at 7th floor and below were still intact it is the transfer trusses at 7th/5th floor below the 'shaft' through which that debris was falling that would be crushed. That is essentially free fall fo rthat debris.

Assume a 1000 kg of rooftop equipment is falling for 5 seconds at gravitational acelleration.
It will be going 50 m/s (rounded up)
Its kinetic energy would be over 1.2 million J

That's for basically one ton of debris.

Compromise the core and transfer system at the 7th/5th floor and the entire building will fall 5 to 7 floors with very little to stop resist it. the air in the bottom 7 floors has ample exit channels through the south side which has almost all of the windows on that side torn away as well as gashes that go deeper into the structure that just the facade/perimeter structure.

[Newtons Bit]

Hey Greg,

Can you point me towards the method you used to calculate the energy required to move the air? Thanks.

[Newtons Bit]

If the east penthouse "crushes" through the building, how long will it take to get to the 7th floor? I think a momentum/energy calc will show that it can't reach the 7th floor in 6-7 seconds.

I think you're confusing failure mechanisms. The penthouse dropped because the framing below it failed. The framing below it failed because a column near the bottom of the tower dropped.

It shouldn't be confused with a WTC1/2 mechanisms with a large upper block. The penthouse in WTC7 dropping first is indicative of large structure failures lower down in the tower rather than at that floor. This failure is something that the tower could resist at least momentarily while the penthouse itself. could not.

[GregoryUrich]

The east penthouse collapse must have caused internal damage.

See here: http://www.youtube.com/watch?v=Y5_e5yROoqY

Beneath the penthouse we see a shockwave travel to ground level, the building bulges and flexes, then global collapse ensues.

Inprecise choice of wording on my part.

there would be no momentum transfer if it does not hit anything on the way down.

The east penthouse fell in due to some damage occuring well donw in the building. The load could not be supported by the columns that failed. The equipment that then fell was doing so into a space that had relatively little to stop its desent since anything in that path had already collapsed or at least started moving before the penthouse debris did.

Assuming though that the core structure west of that location and the system of load transfer members at 7th floor and below were still intact it is the transfer trusses at 7th/5th floor below the 'shaft' through which that debris was falling that would be crushed. That is essentially free fall fo rthat debris.

Assume a 1000 kg of rooftop equipment is falling for 5 seconds at gravitational acelleration.
It will be going 50 m/s (rounded up)
Its kinetic energy would be over 1.2 million J

That's for basically one ton of debris.

Compromise the core and transfer system at the 7th/5th floor and the entire building will fall 5 to 7 floors with very little to stop resist it. the air in the bottom 7 floors has ample exit channels through the south side which has almost all of the windows on that side torn away as well as gashes that go deeper into the structure that just the facade/perimeter structure.

Check out Mancman's observation that an impulse is visible in the facade traveling downward. I interpret this as the falling east penthouse hitting the 47th floor. I think that if the was failure lower down to the extent you are describing we would see some flexing of the facade traveling upwards.

[GregoryUrich]

Hey Greg,

Can you point me towards the method you used to calculate the energy required to move the air? Thanks.

Hi NB,

Basic inertia. I give a simple explanation in the OT and the spread-sheet has the details. I think you'll understand it if you look at the spread-sheet. By the way, I have over-estimated somewhat because I used a square building instead of trapezoidal.

[SDC]

We are looking at videos and photos which are evidence. You seem convinced that the inside collapsed based on that we can "see" the east penthouse collapsing. We can't see what's happening in the building. At least I'm talking about stuff I can see.

So I'm late.

I'm pointing out that when you talk about what you think you see you have no special credibility. An engineer, which is what I gather you are, should understand that what seems to appear on the surface of an event is not what is actually going on.

The eye is a liar.

[SDC]

SDC, I didn't provide an opinion. I pointed out the sticking points many people would naturally have with the fall of WTC 7.

I provided a photo library and asked if anyone has the originals of the following 2 images. That's all.

http://www.sharpprintinginc.com/911_old/Photo_archives/wtc_7/wtc7cornercomp2ahireswx4.jpg

One of these 2 images is a fake. Someone has tried to lie to us. This is a fact and not an opinion.
Given the original images we can learn which one is a fake.


Why is this information useless?

From what I have read of your comments in recent months, you appear to have no special expertise; just a determination to prove that the buildings were destroyed by some sort of controlled demolition. I think that is bilge. As to the quality of these 2 photos I have no opinion.

ETA: see Norseman's post, #73. I do not accept your "fact." Perhaps you could start explaining the problem with the pictures rather than making assertions.

ETA again: I may have tangled up the quote feature. I apologize for this.

[jaydeehess]

Check out Mancman's observation that an impulse is visible in the facade traveling downward. I interpret this as the falling east penthouse hitting the 47th floor. I think that if the was failure lower down to the extent you are describing we would see some flexing of the facade traveling upwards.

No, I do not think you see that there was a column failure and thus a hole in the building that precipitated the east penthouse collapse.

The east penthouse was a large structure taking up approx 1/4 of the roof of the building. Seems to me someone else in another thread had shown that an upward progresssing flexing is seen in the structure that lines up with the original 'kink' in the building and the spot at which the penthouse folds into.
Before the roof of the east penthouse begins falling in there is already debris that was in the east penthouse falling through the hole created by the column failure.

The proposal in appdx "L" of the NIST report is that one or two columns failed below the 13th floor and that the load on that(those) columns could not be redistributed causing an upwards progressing failure along those columns. This may have been due to a particularily massive load in the penthouse directly over on or two columns and which had not been sufficiently spread to other columns.
So you have a hole in the building only at that area along those columns all the way to the east penthouse. Anything directly over that spot would now be falling through that hole. Then the roof cannot hold the load in the penthouse and it starts to fold into the now ever widening hole collapsing the floor span under that widening hole and progressing downwards through the building. Floor pans fail in a downward progressing 'shockwave' from the falling debris but anything that fell into the first hole caused by the original column failure has already been falling and is not hitting anything until it gets to the level of the original column failure.

So far the local failure has been halted, probably by the floor pan beams, from too much of a horizontal progression. If this was as far as it got there would have been a large hole in the building but it would have stayed upright.
However, the debris that started falling as soon as the column failure opened up the rooftop has been acellerating with pretty much nothing opposing it. It then hits the transfer truss system and fails that, which pulls or otherwise compromises the core column system at the 7th floor which holds the beams that are over the Con -ed building and tied into the Con-ed's column system. But the Con-ed building could not be expected to hold up the mass of 40 storeys above it, it needed the core columns to do that by holding one end of those transfer beams. Those beams also hold the north perimeter columns above the 7th floor in short cantilever. So now you have a 40 storey building coming down on the original 7 storey building.

This is, as I stated above I believe, akin to a human stepping on an egg carton. Yes there would be some resistance, I am sure an egg carton offers some resistance to a 200 lb man stepping on it too, but would it be significant?

At this point the entire structure over the Con-ed building will fall 7 storeys. It is attached to the south part of the building only by the floor pans and the south perimeter is compromised from the impact of WTC 1 debris. The southern part of the building is thus not going to offer much in the way of resistance. The eastern portion of the building is also attached via the floor pans except in the area where the hole had opened up. If there was sufficient column strength the eastern portion might have ripped loose from the rest of the building and remained upright. There was not. Instead we see the structure kink and the eastern portion buckle as the western portion falls. Indeed much of the eastern portion fell north and east rather than into the 'footprint' of WTC 7.

[Mancman]

Check out Mancman's observation that an impulse is visible in the facade traveling downward. I interpret this as the falling east penthouse hitting the 47th floor. I think that if the was failure lower down to the extent you are describing we would see some flexing of the facade traveling upwards.

Other footage indicates the penthouse fell much further than one floor, in this you see nearby smoke is dragged down towards the hole:
CPa2PXJS8yA

To me, this indicates the hole was of substantial depth.

[Sizzler]

bump...

[Major_Tom]

Thanks for the info, Norseman, quoted below'

Both images are genuine. I debated this in great detail with Christopher7 last year here (post #3673) and on the following pages including post #3751 in that thread.

You will find the photo on the left hand side in NIST interim report on WTC 7. And the photo on right hand side you will find here, it is the last one before the night shots at the bottom of the page:
http://www.amanzafar.com/WTC/index.shtm

For some real good examples on light refraction effects look at the photos on page 66 and 63 (PDF page 78 and 76) in the report on One Meridian Plaza fire.

The 2 photos in question are reproduced below

http://www.sharpprintinginc.com/911_old/Photo_archives/wtc_7/copyofsw11th7.jpg

http://www.sharpprintinginc.com/911_old/Photo_archives/wtc_7/wtc7_damage.jpg

The close-up and cropped comparison is once again shown below

http://www.sharpprintinginc.com/911_old/Photo_archives/wtc_7/wtc7cornercomp2ahireswx4.jpg

The Zafar and NIST-NYPD photos cannot possibly both be real.

As Norseman pointed out, this was discussed in great detail by Christopher7 around here (http://forums.randi.org/showthread.php?postid=2990310#post2990310)

The counter-arguments given be Norseman and Dave Rogers, among others, were basically that the difference in the 2 photos is merely an optical illusion created by light refraction produced by the extreme heat. In other words, you can't beleive your eyes.

This is absurd (not the people but the counter-arguments).

Since this was discussed elsewhere, I wouldn't want this thread to be dominated by this discussion. I just want to point out to Gregory that NIST and is implanting a falsified photo (with a New York Police Dept stamp) into their report to exaggerate the damage to WTC 7.

This is serious in itself and something you should keep in mind.

As with Christopher7, Dave Rogers may insist that this is indeed the effects of light refraction and tell us to simply read a physics textbook on optics. I have a couple of degrees in physics myself, and you don't need to do that in order to understand that there is NO WAY IN HELL that the difference is attributable to refraction of light within the heated atmosphere around the building.

[Major_Tom]

Double posted..,.deleted

[WildCat]

The Zafar and NIST-NYPD photos cannot possibly both be real.
I don't see why not.

[pomeroo]

Thanks for the info, Norseman, quoted below'



The 2 photos in question are reproduced below

http://www.sharpprintinginc.com/911_old/Photo_archives/wtc_7/copyofsw11th7.jpg

http://www.sharpprintinginc.com/911_old/Photo_archives/wtc_7/wtc7_damage.jpg

The close-up and cropped comparison is once again shown below

http://www.sharpprintinginc.com/911_old/Photo_archives/wtc_7/wtc7cornercomp2ahireswx4.jpg

The Zafar and NIST-NYPD photos cannot possibly both be real.

As Norseman pointed out, this was discussed in great detail by Christopher7 around here (http://forums.randi.org/showthread.php?postid=2990310#post2990310)

The counter-arguments given be Norseman and Dave Rogers, among others, were basically that the difference in the 2 photos is merely an optical illusion created by light refraction produced by the extreme heat. In other words, you can't beleive your eyes.

This is absurd (not the people but the counter-arguments).

Since this was discussed elsewhere, I wouldn't want this thread to be dominated by this discussion. I just want to point out to Gregory that NIST and is implanting a falsified photo (with a New York Police Dept stamp) into their report to exaggerate the damage to WTC 7.

This is serious in itself and something you should keep in mind.

As with Christopher7, Dave Rogers may insist that this is indeed the effects of light refraction and tell us to simply read a physics textbook on optics. I have a couple of degrees in physics myself, and you don't need to do that in order to understand that there is NO WAY IN HELL that the difference is attributable to refraction of light within the heated atmosphere around the building.


If you have "a couple of degrees in physics," why can't you-- Never mind. Forget it. It's been said many times. Just--never mind.

[DGM]

Gregory:
I know you were going to rethink (after reading R Mackey's posts) some of your calculations on this subject. I guess this is a bump to continue what I think is an interesting line of study.
Any thoughts? (ignoring the distractions and focusing on the op)

ETA This is not an attempt to call you out. I'm truly interested in your calculations.

[GregoryUrich]

Thanks for the info, Norseman, quoted below'



The 2 photos in question are reproduced below

http://www.sharpprintinginc.com/911_old/Photo_archives/wtc_7/copyofsw11th7.jpg

http://www.sharpprintinginc.com/911_old/Photo_archives/wtc_7/wtc7_damage.jpg

The close-up and cropped comparison is once again shown below

http://www.sharpprintinginc.com/911_old/Photo_archives/wtc_7/wtc7cornercomp2ahireswx4.jpg

The Zafar and NIST-NYPD photos cannot possibly both be real.

As Norseman pointed out, this was discussed in great detail by Christopher7 around here (http://forums.randi.org/showthread.php?postid=2990310#post2990310)

The counter-arguments given be Norseman and Dave Rogers, among others, were basically that the difference in the 2 photos is merely an optical illusion created by light refraction produced by the extreme heat. In other words, you can't beleive your eyes.

This is absurd (not the people but the counter-arguments).

Since this was discussed elsewhere, I wouldn't want this thread to be dominated by this discussion. I just want to point out to Gregory that NIST and is implanting a falsified photo (with a New York Police Dept stamp) into their report to exaggerate the damage to WTC 7.

This is serious in itself and something you should keep in mind.

As with Christopher7, Dave Rogers may insist that this is indeed the effects of light refraction and tell us to simply read a physics textbook on optics. I have a couple of degrees in physics myself, and you don't need to do that in order to understand that there is NO WAY IN HELL that the difference is attributable to refraction of light within the heated atmosphere around the building.

Light refraction?! That's the skeptic equivalent of DEWs. However, I would be more inclined to believe that NIST was fed bogus photos and didn't question them. I think it would be meaningful to ask NIST to explain the discrepancy.

[GregoryUrich]

Gregory:
I know you were going to rethink (after reading R Mackey's posts) some of your calculations on this subject. I guess this is a bump to continue what I think is an interesting line of study.
Any thoughts? (ignoring the distractions and focusing on the op)

ETA This is not an attempt to call you out. I'm truly interested in your calculations.

I'm going to be traveling this a week, so I won't get a chance to do anything until next week.

[hamelekim]

What? You have zero idea how strong the building is at 5 pm after burning all day. The building was on fire all day and that fire was not fought. You will have zero ability to apply any steel strength at the time WTC7 fails to stand due to fire and damage. There is no survival for buildings that burn and are not fought like WTC7. Please present a building, and office building that burned all day and did not have structural failure. Have you even researched WTC7; I have to say no, since your posts reflect no insight into anything about WTC7.

Your Quixotic attack lacks a knowledge of structures, and you seem to lack any experience on anything about 9/11 until you are guided by people here at JREF. Each time you come up with a new thesis, the work is done by JREF by critiquing you to correctness. Just look back to each of your projects and attempt to support 9/11 truth's lies and false information.

The more you post the more it becomes clear you lack knowledge on 9/11 issues until people, even lay people, guide your research and correct your errors. Between your brief successes at understanding, you display total lack of knowledge (you even mention PNAC, a true flag for someone who lacks fundamental knowledge on 9/11) on each new endeavor to save the 9/11 truth movement form total implosion which actually occurred 6 years ago, pre-debunked on 9/11. Does anyone in 9/11 truth study 9/11 before making all the false statements and made up theories that lack evidence?

Please study WTC7 before you post more junk and have to learn on the post, so your veiled scientific approach resembles an attempt by the engineer you claim to be. If you do not study first, you will do more damage to the prestige of being called an Electrical Engineer; you need to be more supportive of our shared degree and at least appear more knowledgeable on WTC7 even though your conclusion is wrong before you started (yes, everyone knows you have signed the petition of 9/11 truth before having real evidence, the best you can do is mention PNAC, to support the hearsay conclusion of 9/11 truth; so, yes your conclusion is known even if you want to hide behind your shallow research, as if you are really trying to find the truth, which 9/11 TM has never even got close to doing).

I can't wait to see if you think it was silent RDX, or thermite. Please study first so you look better than the no plane guys, and beam weapon dustification experts.

When has there ever been a fire in a tall building that ever caused it to fall? What building has fallen down, from structural damage, in a way that looks exactly like it was controlled demolition?

How weak would the steel be in a building like that, on the floors where the fire was? I'm sorry but the argument is so bloody weak for structural damage bringing the building down.

You also have, on tape, records of warning from officials that the building was being brought down. Why would they say it was being brough down, or know it was coming down at that moment? Why would they even consider that idea when it has never happened in the history of tall buildings.

The heat from those fires would never get hot enough to weaken the structural steel enough to bring them down. The same goes for the WTC buildings. The heat required to make then red hot, wasn't even reached, even then they would be strong enough to hold the building up.

I don't honestly understand why some people completely dismiss the idea that their government could do such an act.

Considering what is going on in the US today, it's well on the way to a fascist state.

[LashL]

However, I would be more inclined to believe that NIST was fed bogus photos and didn't question them. I think it would be meaningful to ask NIST to explain the discrepancy.


So, you are "more inclined to believe that NIST was fed bogus photos" but you haven't done a damned thing to refute those photos except regurgitate tinhat nonsense found and repeated on the Internet. Why not?

And you "think it would be meaningful to ask NIST to explain the discrepancy " (what discrepancy?) but you haven't actually made any such inquiries of NIST. Why not?

What's stopping you?

[Walter Ego]

I don't honestly understand why some people completely dismiss the idea that their government could do such an act.

Considering what is going on in the US today, it's well on the way to a fascist state.



The very fact that the 9-11 Truth movement exist proves that America (or should I say Amerika?) is not yet a fascist state. The left has been saying fascism is just around the corner for the last 40+ years and it hasn't arrived yet. Wake me up when it gets here.

[fullflavormenthol]

The very fact that the 9-11 Truth movement exist proves that America (or should I say Amerika?) is not yet a fascist state. The left has been saying fascism is just around the corner for the last 40+ years and it hasn't arrived yet. Wake me up when it gets here.
Agreed. Screaming fascism is like invoking Orwell for everything. It may sound cool to people who don't understand either, but it makes both into nothing more than a joke that will get ignored.

[fullflavormenthol]

The Zafar and NIST-NYPD photos cannot possibly both be real.

Okay I just have to ask. How do you know there not real? You see photo fakery leaves signs, no matter how good you are at it. So the real question is to show how the photo is fake. Where are the cloned repetitions, where are the out of place shadows, where are the signs of digital fakery?

[hamelekim]

The very fact that the 9-11 Truth movement exist proves that America (or should I say Amerika?) is not yet a fascist state. The left has been saying fascism is just around the corner for the last 40+ years and it hasn't arrived yet. Wake me up when it gets here.

Are you really this ignorant?

http://www.guardian.co.uk/world/2007/apr/24/usa.comment

If you dismiss this then you are completely brainwashed. You don't honestly think that the government is making you safer by tracking every single individual, do you? Do you research waht they have planned in the future? What they want to put in place?

They want to track every single person, your vehicle, your body, what you buy, what you read, the list goes on. They treat you as the enemy. I just can't believe that you don't see this happening. It's like you're living in a fantasy world where governments always do what's best for the people. Democracy is rare in the history of humanity. It's always been rule by the elite, and once they gain power they do not easily give it up.

I can guarantee that you will se an attack in the next 5 years on a US city, likely with a nuclear weapon, dirty bomb, or biological attack. Whatever president is governing at that time will use the powers Bush has gained for the president to take complete control of the country and remove everyones sovereignty in the name of protecting the epople.

In fact, I wouldn't doubt that it happens before the elections this fall, and that those elections are suspended, possibly indefinitely, and a war begins with Iran, which will be blamed for the attack.

You don't see that people are being conditioned to accept all of these eventual changes gradually? It's obvious to anyone who knows history and knows what the neocons want. Read the New American Century, read about the neo conservatives and their ideas. Realize that the US government has known about attacks on the US in the past and ignored them, to get the people angry enough to justify military actions. Realize that they have planned attacks on American people in the past, but sane people overturned the ideas.

You cannot always count on sane people to be in charge. It's a well known fact that the neo conservatives in power were known as the crazies back in the 80's. They were called crazy for a good reason. They are fundamentalist in their beliefs and their beliefs are based on false premises that consistantly are proven wrong through the failure of their actions.

[fullflavormenthol]

Are you really this ignorant?....

....You cannot always count on sane people to be in charge. It's a well known fact that the neo conservatives in power were known as the crazies back in the 80's. They were called crazy for a good reason. They are fundamentalist in their beliefs and their beliefs are based on false premises that consistantly are proven wrong through the failure of their actions.
Okay. Were do I begin? "They". The mysterious "they" is never a good way to go about your argument. I can also tell that someone is an Alex Jone's fan. The good news is they will never be able to track all the things you listed. I have read the same things you have, and much of it is exaggerated from its original source.

Yeah government is bad. Congrats on coming to the conclusion of many others through the years. Democracy is rare, which why we don't have one.

Democracy is also really, really bad.

Elites. People with power will always run things, because even in a Republic most people will never seek to attain it. Elites in most societies are just those people who actually seek to run things.

I can guarantee that you will se an attack in the next 5 years on a US city, likely with a nuclear weapon, dirty bomb, or biological attack.

1. I can guarantee a traffic accident in the next 5 hours. 2. Truthers have been saying this ever since 9-11, 3. Even if it does happen that wouldn't mean the government did it.

In fact, I wouldn't doubt that it happens before the elections this fall, and that those elections are suspended, possibly indefinitely, and a war begins with Iran, which will be blamed for the attack.

Alex Jones has been saying that about every election. The exact statement you make has been repeated since 2004. Still the same cabal that pulled off the worlds most perfect conspiracy have failed to flex this power for total control.

The rest dude is like a verbatim rant from Terrorstorm. Also Northwoods is so misrepresented. It was never a "plan" in the since truthers claim it was. It was a proposal that got someone immediately fired.

[Dave Rogers]

Light refraction?! That's the skeptic equivalent of DEWs. However, I would be more inclined to believe that NIST was fed bogus photos and didn't question them. I think it would be meaningful to ask NIST to explain the discrepancy.

There are aspects of the differences that look like refraction, specifically the wavy appearance of some of the features of the processed photo that was originally posted a long time ago. There are other aspects that appear to be due to the very different viewing angles. One shot is taken from behind the damaged corner at a glancing angle, so any structure behind the missing parts will be obscured, whereas the other is taken from a viewpoint aimed directly at the corner, and parts of the structure behind the missing parts are visible and tend to fill in areas that look like holes in the first. Overall, I'm not convinced either way as to whether one of the photos has been altered. Given the overwhelming preponderance of evidence against the conspiracy theories I'm not too concerned, but if the USA chooses to waste its money on the new investigation the truthers claim to want then I'm sure that detailed analysis of these photographs would be a suitably pointless way to go about it.

Dave

[Dave Rogers]

I can guarantee that you will se an attack in the next 5 years on a US city, likely with a nuclear weapon, dirty bomb, or biological attack. Whatever president is governing at that time will use the powers Bush has gained for the president to take complete control of the country and remove everyones sovereignty in the name of protecting the epople.

In fact, I wouldn't doubt that it happens before the elections this fall, and that those elections are suspended, possibly indefinitely, and a war begins with Iran, which will be blamed for the attack.

If all that doesn't happen, will you be happy to come back here and admit you were wrong?

Dave

[aggle-rithm]

They want to track every single person, your vehicle, your body, what you buy, what you read, the list goes on. They treat you as the enemy. I just can't believe that you don't see this happening. It's like you're living in a fantasy world where governments always do what's best for the people.

This worries me, until I remember that the contract for tracking every single person, vehicle, purchase, etc., will go to the lowest bidder. Then, more than likely, the whole thing will be subcontracted to India. Language barriers will prevent any meaningful information from being shared with the government. In a few years, the whole stinking mess will be declared a failure and its budgeting cut.

Hey, I can speculate, too. Except my speculations are based somewhat on reality.

[fullflavormenthol]

This worries me, until I remember that the contract for tracking every single person, vehicle, purchase, etc., will go to the lowest bidder. Then, more than likely, the whole thing will be subcontracted to India. Language barriers will prevent any meaningful information from being shared with the government. In a few years, the whole stinking mess will be declared a failure and its budgeting cut.

Hey, I can speculate, too. Except my speculations are based somewhat on reality.
Ha. It is true! What gets to me is that I am concerned about civil liberties, but pretending that all this is going to be one massive system doesn't help my own case about it being wrong. It will be like everything else in government when it comes to taxes and motor vehicles, completely screwed and poorly managed.

[aggle-rithm]

Ha. It is true! What gets to me is that I am concerned about civil liberties, but pretending that all this is going to be one massive system doesn't help my own case about it being wrong. It will be like everything else in government when it comes to taxes and motor vehicles, completely screwed and poorly managed.

I write systems that do exactly the sort of tracking that hamelekim is talking about, but of course, not on the scale he's talking about.

I can guarantee that, if the government were really working on such a system, it would be by far the largest engineering project in human history. There would have to be thousands upon thousands of people working on it, and it would be virtually impossible to keep it secret.

I don't think I have to mention that the government has a very poor track record of implementing projects like this...the overhaul of the Air Traffic Control system took many years and many millions of dollars and was a complete failure.

[chillzero]

This isn't a thread about civil liberties - start a new thread for that, and stay on topic here please.

[Major_Tom]

Light refraction?! That's the skeptic equivalent of DEWs. However, I would be more inclined to believe that NIST was fed bogus photos and didn't question them. I think it would be meaningful to ask NIST to explain the discrepancy.

That's what I assumed also.

But the photo is stamped "New York Police Department" and was taken by helecopter.


Do you see the implications? This isn't just an honest mistake. NYPD?

[fullflavormenthol]

That's what I assumed also.

But the photo is stamped "New York Police Department" and was taken by helecopter.


Do you see the implications? This isn't just an honest mistake. NYPD?
Where is the evidence that NYPD photo has been faked? I asked before, and I would like to get an answer. That is a big acquisition, and I don't think you have made your case.

[uk_dave]

Where is the evidence that NYPD photo has been faked? I asked before, and I would like to get an answer. That is a big acquisition, and I don't think you have made your case.

'Truthers' seem to think that the dark patches are being used as evidence of severe structural damage, whereas, in fact, they are just areas of dark smoke which obscure parts of the building and which appear in both photographs.

[SDC]

That's what I assumed also.

But the photo is stamped "New York Police Department" and was taken by helecopter.


Do you see the implications? This isn't just an honest mistake. NYPD?

Let me put this as a question. Are you stating that the fact that the photo was, evidently, taken by the NYPD, means necessarily that it was faked? Or are you implying that?

[Newtons Bit]

Thanks for the info, Norseman, quoted below'



The 2 photos in question are reproduced below

http://www.sharpprintinginc.com/911_old/Photo_archives/wtc_7/copyofsw11th7.jpg

http://www.sharpprintinginc.com/911_old/Photo_archives/wtc_7/wtc7_damage.jpg

The close-up and cropped comparison is once again shown below

http://www.sharpprintinginc.com/911_old/Photo_archives/wtc_7/wtc7cornercomp2ahireswx4.jpg

The Zafar and NIST-NYPD photos cannot possibly both be real.

As Norseman pointed out, this was discussed in great detail by Christopher7 around here (http://forums.randi.org/showthread.php?postid=2990310#post2990310)

The counter-arguments given be Norseman and Dave Rogers, among others, were basically that the difference in the 2 photos is merely an optical illusion created by light refraction produced by the extreme heat. In other words, you can't beleive your eyes.

This is absurd (not the people but the counter-arguments).

Since this was discussed elsewhere, I wouldn't want this thread to be dominated by this discussion. I just want to point out to Gregory that NIST and is implanting a falsified photo (with a New York Police Dept stamp) into their report to exaggerate the damage to WTC 7.

This is serious in itself and something you should keep in mind.

As with Christopher7, Dave Rogers may insist that this is indeed the effects of light refraction and tell us to simply read a physics textbook on optics. I have a couple of degrees in physics myself, and you don't need to do that in order to understand that there is NO WAY IN HELL that the difference is attributable to refraction of light within the heated atmosphere around the building.


I see nothing wrong with those two photos. Both are legit and they are not mutually exclusive. The one on the left shows a gash in the corner, and it's easy to see because it's isometric. The one on the right is almost a pure elevation, you can't see the gash easily (though if you try to get past your truther mental problems you can) because the building beyond the gash masks it. It's not rocket science.

[Major_Tom]

Let me put this as a question. Are you stating that the fact that the photo was, evidently, taken by the NYPD, means necessarily that it was faked? Or are you implying that?

Of course not. It means that the chain of custody doesn't involve some privte party that could have silpped a fake photo to NIST unaware of what they were doing.

If this photo is fake, and it seems that it is, it is not just an accidental slip-up that it appears in the NIST report. IT wasn't faked by some private party prankster.

As Dave mentioned, it has been discussed at length elsewhere by Christopher7 and for those not familiar with the arguments for and against fakery, it is best to read that thread first..

If we are to discuss this, it is probably best to do it on that thread so we can include C7 in the discussion and draw on the resources already available.

The link to that discussion is at

http://forums.randi.org/showthread.php?postid=2990310#post2990310

[fullflavormenthol]

Of course not. It means that the chain of custody doesn't involve some privte party that could have silpped a fake photo to NIST unaware of what they were doing.

If this photo is fake, and it seems that it is, it is not just an accidental slip-up that it appears in the NIST report. IT wasn't faked by some private party prankster.

As Dave mentioned, it has been discussed at length elsewhere by Christopher7 and for those not familiar with the arguments for and against fakery, it is best to read that thread first..

If we are to discuss this, it is probably best to do it on that thread so we can include C7 in the discussion and draw on the resources already available.

The link to that discussion is at

http://forums.randi.org/showthread.php?postid=2990310#post2990310
Yes I have been through that thread, and Christopher7 merely accuses one photo of being a fake. The problem is, that there would be evidence of fakery. Where is that evidence? Pixels out of place, repetitions that shouldn't be there, uniformed appearance showing artistry?

Is it an actual building or are you saying that the damage has been added after the fact?

[Corsair 115]

If this photo is fake, and it seems that it is...Please start a thread where you detail your reasons for thinking this. A full analysis to support your supposition.

[jaydeehess]

I see nothing wrong with those two photos. Both are legit and they are not mutually exclusive. The one on the left shows a gash in the corner, and it's easy to see because it's isometric. The one on the right is almost a pure elevation, you can't see the gash easily (though if you try to get past your truther mental problems you can) because the building beyond the gash masks it. It's not rocket science.

here, here

That is about as well as anyone could put it.

[Major_Tom]

On the floors labeled 14 and 15 on the right, you can't see a corner? The reflection of the sunlight shows a straight corner. It lines up perfectly with the visible corner above. You really can't see that?

http://www.sharpprintinginc.com/911_old/Photo_archives/wtc_7/wtc7cornercomp2ahireswx4.jpg


Black is white. Freedom is slavery. 2+2=5. Surreal

[fullflavormenthol]

On the floors labeled 14 and 15 on the right, you can't see a corner? The reflection of the sunlight shows a straight corner. It lines up perfectly with the visible corner above. You really can't see that?

http://www.sharpprintinginc.com/911_old/Photo_archives/wtc_7/wtc7cornercomp2ahireswx4.jpg


Black is white. Freedom is slavery. 2+2=5. Surreal
So where is the evidence that the photo was faked? Okay. You are saying they look different without taking into regards the myriad of issues. The angle is one major issue, and that even in the other thread C7 couldn't narrow down the time enough. Still the issue is, that if the photo is faked; where is the evidence?

Black is white. Freedom is slavery. 2+2=5. Surreal

Don't invoke Orwell as if that proves your point. That is the first pointer I am going to give to you.

BTW (Off topic), the statement '2+2=5' is actually a true statement. What Orwell is getting at is a person's freedom to say that the more obvious statement '2+2=4' is true. BOTH are actually true statements.

[GregoryUrich]

So, you are "more inclined to believe that NIST was fed bogus photos" but you haven't done a damned thing to refute those photos except regurgitate tinhat nonsense found and repeated on the Internet. Why not?

And you "think it would be meaningful to ask NIST to explain the discrepancy " (what discrepancy?) but you haven't actually made any such inquiries of NIST. Why not?

What's stopping you?

Derail. Any comments on the OT?

[A W Smith]

On the floors labeled 14 and 15 on the right, you can't see a corner? The reflection of the sunlight shows a straight corner. It lines up perfectly with the visible corner above. You really can't see that?

http://www.sharpprintinginc.com/911_old/Photo_archives/wtc_7/wtc7cornercomp2ahireswx4.jpg


Black is white. Freedom is slavery. 2+2=5. Surreal


That photo was taken across the Hudson river from another state. That could easily be column #63 and not a corner at all.

http://www.debunking911.com/WTC7.h3.jpg

[jaydeehess]

Derail. Any comments on the OT?

-initial column failure

-vertical progression failure to the rooftop with floors falling through as the column comes down opening up a space under one or two columns
-equipment in the east penthouse is the last to enter that opening and would have nothing under it to hit until it reached the level of the initial column failure

-rooftop penthouse floor gives way around the original opening which widens the opening and tosses the rest of the contents of the penthoues and the penthouse itself into the widening opening
-the falling debris then continues downward collapsing the floors below it in vertical downward progression

-the rooftop equipment that first fell through the opening (That debris has been in very close to, if not in, free fall) has already hit the truss system and caused greater damage to it which pulls or otherwise compromises the core system of columns which is carrying the south end of the transfer beams over the Con-Edison building.
-core column fail in a horizontal progression west from the original column failure which draws down the core of the building.

-core column failure also causes the mass of the 40 storeys above to now be loaded on the columns of the original Con-Edison building which was, of course, not designed to carry anything close to such a load.
-Con-Edison columns fail quickly. The north face columns below the 7th floor tilt inward drawn in by their connection to the transfer beams
-the entire 40 storeys, to the north of the core, above the 7th floor falls

-the core failure also draws the south portion of the building inward but the south perimeter column system has been weakened by the impact damage and fails quickly meaning that the south portion of the building also falls.

-the eastern 1/4 of the building has suffered less impact damage, its columns extend from foundation to roof and it resists collapse to some extent. However, of course, each floor is connected to the western portion of the building that is moving downward. There is the existing column loss from the original failure and now a large floor pan opening on many floors. The eastern portion simply does not have the structural ability to tear loose from the western portion and remain standing, the 'kink' illustrates that the western portion is pulling the eastern side.

-the eastern portion folds over part way down, pushing the lower part to the north-east

In the above senario, does what would be expected to be visible from the outside not match what is seen in the videos?

[jaydeehess]

That photo was taken across the Hudson river from another state. That could easily be column #63 and not a corner at all.

http://www.debunking911.com/WTC7.h3.jpg

Note also that there is a setback of the south face below the roof.
The SW corner damage does not extend to completely take out the extension of the sothface at the SW corner..
A picture taken from the NW will not be able to show the remaining portion of that extension whereas a picture taken from the west or SW would. Forshortening due to the telephoto lens would mask the depth between the missing corner and columns beyond the damaged portion.

http://forums.randi.org/imagehosting/1295947f1a63fb6cf5.bmp

ETA: Sorry my little diagram is so small, hope everyone can make out the wording

[fullflavormenthol]

Note also that there is a setback of the south face below the roof.
The SW corner damage does not extend to completely take out the extension of the sothface at the SW corner..
A picture taken from the NW will not be able to show the remaining portion of that extension whereas a picture taken from the west or SW would. Forshortening due to the telephoto lens would mask the depth between the missing corner and columns beyond the damaged portion.

http://forums.randi.org/imagehosting/1295947f1a63fb6cf5.bmp

ETA: Sorry my little diagram is so small, hope everyone can make out the wording
But you are right about the telephoto lens. It is a basic principle that is used to imply congestion in a shot. Film makers use this technique to make a street "feel" more crowded than it really is. It is why shots taken from far away are less reliable than close shots.

Not to mention the smoke, and a myriad of other objects making any real analysis of the photo difficult without reference of several images in a series.

[jaydeehess]

Not to mention the smoke, and a myriad of other objects making any real analysis of the photo difficult without reference of several images in a series.

,,, and the possibility that the numbering of floors in each photo is off.

the fire on floor labeled 7 is pouring a large amount of smoke in one photo as well, whereas in the other only the soot is showing which would suggest that it was taken later in the day and along with that the possibility that portions of the croner fell away between photos.

[deep]

Zero resistance?
I don't believe you (or anyone slse) have shown this.


Thanks- your comment literally made me laugh out loud..

I'm guessing that the near free-fall speed of the collapse isn't enough to convince you, so how should one go about satisfactorily "showing" that the building collapsed without little or no resistance?

In other words, you're demanding "proof" for something that is obvious to any objective-minded observer.

[deep]

But you are right about the telephoto lens. It is a basic principle that is used to imply congestion in a shot. Film makers use this technique to make a street "feel" more crowded than it really is. It is why shots taken from far away are less reliable than close shots.

Not to mention the smoke, and a myriad of other objects making any real analysis of the photo difficult without reference of several images in a series.


It could also be barrel distortion, which is quite common in many popular DSLR lenses (although it's not as big a problem as it may seem like, since Photoshop can reliably correct it). It's tough to say without seeing the original photo in its entirety, or even knowing what percentage of the original photo was cropped out (and which part we're looking at).

[DGM]

Thanks- your comment literally made me laugh out loud..

I'm guessing that the near free-fall speed of the collapse isn't enough to convince you, so how should one go about satisfactorily "showing" that the building collapsed without little or no resistance?

In other words, you're demanding "proof" for something that is obvious to any objective-minded observer.
You really made my day. If it's NEAR free fall there was resistance. Way to stick your foot in your mouth. Don't try to argue things you clearly don't understand, I can easily make you look even more the fool.

[Dave Rogers]

I'm guessing that the near free-fall speed of the collapse isn't enough to convince you, so how should one go about satisfactorily "showing" that the building collapsed without little or no resistance?

You're committing a classic example of the unevaluated inequality fallacy. Let's see how it works.

Let A be the collapse time of WTC7, B be the time for an object to fall from the roof of WTC7 to the ground, and C be the expected collapse time taking into account structural resistance, momentum transfer, air resistance and any other significant factors.

Your statement that the collapse was at "near free-fall speed" is equivalent to stating that A > B, but that the difference (A-B) is small. It is clear that structural resistance will slow the collapse, so we can assume that C > B. The difference (C-B) is not known at this stage in your analysis because it hasn't been calculated.

You are now stating that because (A-B) is small, (C-B) is therefore much greater than (A-B). This is a non sequitur. We don't know the value of (C-B), therefore we can't determine whether it's greater, smaller or equal to (A-B).

What is ironic is that Gregory, who doesn't suffer from intellectual laziness, is actually trying to calculate C in this thread, yet you've completely ignored his efforts, and in effect stated that they're unnecessary because your conclusion is "obvious to any objective-minded observer". It's no such thing; it's actually only obvious to the biased observer who makes no attempt to analyse his observations beyond a superficial attempt to reconcile them with his own prejudices. And this on a skeptics' forum.

Dave

[deep]

You really made my day. If it's NEAR free fall there was resistance. Way to stick your foot in your mouth. Don't try to argue things you clearly don't understand, I can easily make you look even more the fool.


LOL, you're on a roll.. I said "near free-fall speed" because I don't feel like getting into an argument over how to measure the speed of a building collapse. Yes, there was obviously resistance present when the penthouse first started to fall (while the rest of the building was clearly still being supported), but after that it came down at free-fall speed.

So yeah, nice job "making me look even more the fool" (sic). Try to form a coherent sentence next time you feel the urge to insult someone.

[DGM]

LOL, you're on a roll.. I said "near free-fall speed" because I don't feel like getting into an argument over how to measure the speed of a building collapse. Yes, there was obviously resistance present when the penthouse first started to fall (while the rest of the building was clearly still being supported), but after that it came down at free-fall speed.

So yeah, nice job "making me look even more the fool" (sic). Try to form a coherent sentence next time you feel the urge to insult someone.
How much is ZERO? Can you read?

[deep]

You're committing a classic example of the unevaluated inequality fallacy. Let's see how it works.


Unevaluated inequality fallacy? Sorry, but I'm not going to waste my time refuting imaginary fallacies, especially when you consider the numerous circumstantial generalization fallacies present in your explanation.

What is ironic is that Gregory, who doesn't suffer from intellectual laziness, is actually trying to calculate C in this thread, yet you've completely ignored his efforts


You've obviously overlooked the fact that it was Gregory who originally made the comment about zero resistance. Don't allow little details like that to get in the way of condemning me, though. April fools?

[deep]

How much is ZERO? Can you read?


In this context, "zero" would mean free-fall speed, which is the speed at which the building collapsed. Like I said, I was was initially adapting to your methodology for timing the collapse - I don't agree with it, because the rest of the building was obviously still being supported at that time.

[Dave Rogers]

Unevaluated inequality fallacy? Sorry, but I'm not going to waste my time refuting imaginary fallacies, especially when you consider the numerous circumstantial generalization fallacies present in your explanation.

If you want to identify those fallacies and describe how they work in detail, please feel free to do so. Otherwise, you're at best just committing a tu quoque fallacy.

You've obviously overlooked the fact that it was Gregory who originally made the comment about zero resistance. Don't allow little details like that to get in the way of condemning me, though. April fools?

You've obviously overlooked the fact that Gregory presented his results as tentative and open to discussion, rather than immediately claiming that anyone who disagrees with him is dishonest. You've also obviously overlooked the fact that, when Ryan Mackey pointed out some shortcomings in his analysis, Gregory acknowledged them with thanks and added the comment that on further reflection he may have to revise his estimates of air resistance downwards, implying that the structural resistance now appears to be non-zero. But that would get in the way of assuming that anyone who disagrees with your snap judgements must be lying.

Dave

[DGM]

In this context, "zero" would mean free-fall speed, which is the speed at which the building collapsed. Like I said, I was was initially adapting to your methodology for timing the collapse - I don't agree with it, because the rest of the building was obviously still being supported at that time.
Did you actually read what Gregory and I were talking about before you jumped it? His calculations proving zero resistance. Did you happen to notice were he says he's got to revise his calculations? Do you think they're still going to show zero resistance? I don't.

BTW WHERE DID THE PENTHOUSE GO?

[Dave Rogers]

Getting back to the OP here: Gregory, while I think your aims are laudable, I think they're also unachievable. Here's why.

Let's take a slightly different approach, and look at the rate at which air has to be expelled from between two floors in order for complete collapse. For generality, consider firstly a pair of floor slabs, initially separated by height z, with area A and perimeter length S. In a time interval dt, the upper slab falls through a distance dz, giving an instantaneous velocity of dz/dt in the direction of negative z. An element dV of volume of air is expelled through an area Sz(t), and we can calculate that dV=Adz. The velocity at which the air is expelled is therefore Adz/Sz(t)dt = A/Sz(t) times the rate of fall of the upper block. All the values in this expression are positive except for z(t), which goes to zero at the moment of impact of the two slabs; at the point of impact, in this simple model, the air is expelled with infinite velocity, and the energy loss is therefore infinite.

Clearly this approach is physically unrealistic. However, the only way to recover a finite velocity is to retain a finite aperture for the air to be expelled through. This requires that either (a) some further disruption of the structure allows air to be expelled elsewhere, or (b) the slabs do not come into contact. (b) is, again, physically unreasonable in this instance. So, in order to obtain physically reasonable behaviour, it is necessary to assume that the floor slabs are broken before impact. The precise energy loss, therefore, becomes entirely dependent on the assumptions made about how much damage a floor slab suffers before striking the ground, and this is an area where we have no information to work from.

Another point to consider is the effect of the east penthouse. I agree with your surmise that it could not have reached ground level in the ~6 seconds before the facade collapse, but it is certain that the remains of this structure would have reached ground level well in advance of the end point of the collapse. From this point on, any air resistance to collapse must have been drastically decreased, because even assuming the penthouse punched a perfectly regular hole in every floor slab - a wildly unrealistic assumption; some further collateral damage seems inevitable - by the time it reached the ground then something like one-third of the building area allowed unrestricted egress of air.

For these reasons, I think the air resistance of the structure is intractable to calculation. I'm not sure your approach can even give a reliable limit, in either direction; in particular, the assumption that the entire volume of air between two floor slabs must be expelled through the perimeter, seems thoroughly untenable, as it relies on the floor slabs being substantially undamaged until they strike the ground.

Moving on to a more tangential point, let's assume that your hypothesis in the OP were correct, and that the structural resistance to collapse was zero. This requires that at least the majority of columns were severed by other means prior to impact with the ground. While the core columns might be severed without the means being visible on videos of the collapse, this could not be the case for the perimeter columns. Your hypothesis therefore requires that either the perimeter columns were comprehensively structurally disrupted at the moment of collapse initiation by some means invisible to video, which rules out any possible explosive device, or that they were structurally disrupted by a series of sufficiently precisely timed explosive devices as they entered the collapse zone, requiring detonation timings with a precision significantly better than one-tenth of a second. I would go so far as to say the first possibility is simply ruled out by observation. What, then, would be the point of the second, when its only possible function would be to accelerate the collapse of a building already certain to collapse without its use?

While I appreciate that you feel you've discovered a possible anomaly, this anomaly (if valid) doesn't suggest a sane alternative hypothesis. A simpler explanation would be that your starting assumptions are oversimplified to the point of invalidity.

Dave

[LashL]

Derail. Any comments on the OT?

If you do not wish your comments to be questioned or discussed, you should refrain from making them. It wasn't me who introduced the photos, and it wasn't me who suggested that one of them must be bogus. Personally, I have seen no evidence that either of them is bogus. Moreover, this thread is ostensibly about your research, and you certainly didn't complain when the photos were introduced, so how is it a derail for me to ask you what you have done about authenticating or refuting them when you have questioned their authenticity in this very thread?

I can certainly understand why you do not wish to answer my straightforward inquiry (since the answer is obviously, "not a darned thing") but to call it a derail when it was, in fact, a direct response to your own words, well, I think thou really doth protest too much.

:rolleyes:

(Apologies to Dave Rogers and jaydeehess and others for posting this in the midst of your informative posts but I felt the need to respond to GregoryUrich's lame post in response to mine, sorry. Now, back to your regularly scheduled debunking. ;))

[Slayhamlet]

LOL, you're on a roll.. I said "near free-fall speed" because I don't feel like getting into an argument over how to measure the speed of a building collapse. Yes, there was obviously resistance present when the penthouse first started to fall (while the rest of the building was clearly still being supported), but after that it came down at free-fall speed.

And you've still provided zero evidence of this claim. People (such as Gregory) with greater curiosity and far less blind devotion to a political agenda than yourself have actually attempted some calculations to prove it one way or the other.

So yeah, nice job "making me look even more the fool" (sic). Try to form a coherent sentence next time you feel the urge to insult someone.

First, when you put quotation marks around words and append "[sic]" to it, the words are supposed to be an exact quotation. Second, the phrase DGM used is a common expression and not at all incoherent.

[R.Mackey]

You've also obviously overlooked the fact that, when Ryan Mackey pointed out some shortcomings in his analysis, Gregory acknowledged them with thanks and added the comment that on further reflection he may have to revise his estimates of air resistance downwards, implying that the structural resistance now appears to be non-zero.

Even Gregory's original post doesn't claim resistance is zero, only that it's surprisingly small. My calculations verify that a small amount of structural resistance is actually expected. Gregory's numbers may not be far off.

The resistance is higher in the WTC 1 and 2 cases, again, because there we have not only structual resistance, but also momentum transfer. It is this momentum transfer that dominates the delay in collapse. In WTC 7, no momentum transfer occurs. That's because the plane of interaction is (roughly) at ground level.

Any argument to the contrary, i.e. "WTC 7 came down too fast," is simply ignorant. Common sense is wrong in this particular problem, and simple mathematics demonstrates this.

[GregoryUrich]

If you do not wish your comments to be questioned or discussed, you should refrain from making them. It wasn't me who introduced the photos, and it wasn't me who suggested that one of them must be bogus. Personally, I have seen no evidence that either of them is bogus. Moreover, this thread is ostensibly about your research, and you certainly didn't complain when the photos were introduced, so how is it a derail for me to ask you what you have done about authenticating or refuting them when you have questioned their authenticity in this very thread?

I can certainly understand why you do not wish to answer my straightforward inquiry (since the answer is obviously, "not a darned thing") but to call it a derail when it was, in fact, a direct response to your own words, well, I think thou really doth protest too much.

:rolleyes:

(Apologies to Dave Rogers and jaydeehess and others for posting this in the midst of your informative posts but I felt the need to respond to GregoryUrich's lame post in response to mine, sorry. Now, back to your regularly scheduled debunking. ;))

My bad. I should have called the derail earlier. My terse reply was in reaction to your insulting approach which attempts to characterize me as a do nothing whiner. I think I have demonstrated my commitment to doing evidence based research and your attack is completely unwarranted.

To answer your question, no I'm not going to pursue that issue. I don't have time to chase every issue which is why I suggested that it was worth pursuing. I am quite busy with a fairly large paper in the works debunking Ross, Kuttler (WTC1) and to some extent Bazant. My preliminary result is that while Bazant and Zhou made egregious omissions, their overall conclusion that collapse would progress (in WTC1) is correct.

[jaydeehess]

Thanks- your comment literally made me laugh out loud..

I'm guessing that the near free-fall speed of the collapse isn't enough to convince you, so how should one go about satisfactorily "showing" that the building collapsed without little or no resistance?

In other words, you're demanding "proof" for something that is obvious to any objective-minded observer.

First of all there "free-fall speed " is a misnomer. Free fall acelleration or free fall time would be correct but not speed.

Secondly you do state that a condition of "no" resistance, ie. equalling zero, could describe what occured. However the only possible way to obtain such would be to destroy every floor's columns, or a large percentage of them, all at the very same time. Since that is not observed as having happened then the condition of "no resistance did not occur.

So that leaves "little resistance" and "near at free fall rate/acelleration/time" which does require that one attempt a quantification of how much resistance there indeed was. GU is moving along those lines and thus obviously not inclined to accept 'common sense' arguements. Too bad more were not like that.

ETA: I see Dave already said much of what I just did

[beachnut]

My bad. I should have called the derail earlier. My terse reply was in reaction to your insulting approach which attempts to characterize me as a do nothing whiner. I think I have demonstrated my commitment to doing evidence based research and your attack is completely unwarranted.

To answer your question, no I'm not going to pursue that issue. I don't have time to chase every issue which is why I suggested that it was worth pursuing. I am quite busy with a fairly large paper in the works debunking Ross, Kuttler (WTC1) and to some extent Bazant. My preliminary result is that while Bazant and Zhou made egregious omissions, their overall conclusion that collapse would progress (in WTC1) is correct.
So is this thread the search for the ample evidence you said you already have to say this? (your B and Z conclusion was as I said; so will this be)
… ample evidence and probable cause to believe that many grave and still unresolved crimes were committed by US officials prior to, during and after the events of 9/11…
… not limited to abetment of mass murder, criminal negligence, insider trading, and obstruction of justice, … Where does WTC7 fit and this thread in you preconceived world of 9/11 truth petition signing and your quest, albeit failed, for truth?

Are you trying to manufacture the evidence you need after you say you had it already? So which part of WTC7 failure fits into your preconceived conclusion? Or are you telling a fib you have "ample evidence"? How can you even waste time on this thread since you have "ample evidence"? Why does the WTC7 even figure in your truth quest and why are people unable to understand the physics of failure?

Seriously, I have studied your thread and it again is a story of you learning about things as you go and try to back in your "ample evidence". Did I miss where you are actually trying to expose the truth, or are you really trying to back in evidence even in this thread of the WTC7? Does this mean you have failed to support thermite and CD in the WTC towers failure, since you have started this thread?

Can you 9/11 truth people ever tell anyone what your real goal is? I mean you have the ample evidence, or do you? I find your OP weak on purpose, and your preconceived conclusion kind of anti-research and knowledge, on the very idea of WTC7 revisited. And still the big question is why is WTC7 important in 9/11 truth fantasy ideas?

Why is 9/11 truth unable to find support from a majority of engineers on topics of WTC7 and their fantasy of CD? I mean 0.00087 percent of all world engineers is not a majority, and there is no real evidence. How can you support 9/11 truth without real evidence to support their conclusions based on hearsay and made up ideas like thermite, and CD? At least you have Deep44 and Major Tom helping you find the "truth"; I wonder what Jones has to add? Ironic stuff.
So how is the WTC7 revisited coming? Oh, you already made up your mind, until you actually have the facts in, dispite the "ample evidence"??

[GregoryUrich]

So is this thread the search for the ample evidence you said you already have to say this? (your B and Z conclusion was as I said; so will this be)
Where does WTC7 fit and this thread in you preconceived world of 9/11 truth petition signing and your quest, albeit failed, for truth?

Are you trying to manufacture the evidence you need after you say you had it already? So which part of WTC7 failure fits into your preconceived conclusion? Or are you telling a fib you have "ample evidence"? How can you even waste time on this thread since you have "ample evidence"? Why does the WTC7 even figure in your truth quest and why are people unable to understand the physics of failure?

Seriously, I have studied your thread and it again is a story of you learning about things as you go and try to back in your "ample evidence". Did I miss where you are actually trying to expose the truth, or are you really trying to back in evidence even in this thread of the WTC7? Does this mean you have failed to support thermite and CD in the WTC towers failure, since you have started this thread?

Can you 9/11 truth people ever tell anyone what your real goal is? I mean you have the ample evidence, or do you? I find your OP weak on purpose, and your preconceived conclusion kind of anti-research and knowledge, on the very idea of WTC7 revisited. And still the big question is why is WTC7 important in 9/11 truth fantasy ideas?

Why is 9/11 truth unable to find support from a majority of engineers on topics of WTC7 and their fantasy of CD? I mean 0.00087 percent of all world engineers is not a majority, and there is no real evidence. How can you support 9/11 truth without real evidence to support their conclusions based on hearsay and made up ideas like thermite, and CD? At least you have Deep44 and Major Tom helping you find the "truth"; I wonder what Jones has to add? Ironic stuff.
So how is the WTC7 revisited coming? Oh, you already made up your mind, until you actually have the facts in, dispite the "ample evidence"??


Beachnut, before I put you back on ignore, I think it is only fair to respond to your continued personal attacks and misrepresentations.

I signed a petition supporting a group pursuing a new investigation. While I do not agree with everything they are saying, I do feel an investigation is warranted.

You, on the other hand, have been an active participant in the war crimes of Desert Storm contributing to the deaths of 1.5 million Iraqis. Do the so called "militants" hate us for "our freedom" OR DO THEY HATE US BECAUSE WE DESTROYED THEIR COUNTRY AND KILLED THEIR LOVED ONES. There is no question in my mind why you are so hostile to any type of investigation which would examine the possible wrong doings of our government and military. I hope you and Norman "bombed them back to the stone-age" Schwarzkopf get what's coming to you.

[fullflavormenthol]

You, on the other hand, have been an active participant in the war crimes of Desert Storm contributing to the deaths of 1.5 million Iraqis. Do the so called "militants" hate us for "our freedom" OR DO THEY HATE US BECAUSE WE DESTROYED THEIR COUNTRY AND KILLED THEIR LOVED ONES. There is no question in my mind why you are so hostile to any type of investigation which would examine the possible wrong doings of our government and military. I hope you and Norman "bombed them back to the stone-age" Schwarzkopf get what's coming to you.

That is a very strong statement to make against someone, and it is a stupid accusation at that. If Desert Storm is a war crime than it would be one committed under the auspices of the U.N. Security Council and NATO.

What is implied to me by that statement is that you hate the military. I don't like the military either, but that is in a general "I don't believe in killing" sort of way. Your statement, though, is more along the line of hating everyone in the military personally.

That and I don't like the "I hope you and Norman "bombed them back to the stone-age" Schwarzkopf get what's coming to you." statement you made. So while I may be new here, I will report it the next time it happens. Because such a statement is the intellectual equivalent of telling someone to go to hell or **** off. It has no place in a forum debate. OR worse, implying that your opponent should have an act of violence visited upon them. The issue is that the phrase "whats voming to you" is a vague and can mean anything, and since you are refering to war crimes, the inference is that violence is that "what's" in the statement.

Accusing someone in a forum of a crime, without any evidence, is a personal attack; one that weakens your position.

[stateofgrace]

Beachnut, before I put you back on ignore, I think it is only fair to respond to your continued personal attacks and misrepresentations.

I signed a petition supporting a group pursuing a new investigation. While I do not agree with everything they are saying, I do feel an investigation is warranted.

You, on the other hand, have been an active participant in the war crimes of Desert Storm contributing to the deaths of 1.5 million Iraqis. Do the so called "militants" hate us for "our freedom" OR DO THEY HATE US BECAUSE WE DESTROYED THEIR COUNTRY AND KILLED THEIR LOVED ONES. There is no question in my mind why you are so hostile to any type of investigation which would examine the possible wrong doings of our government and military. I hope you and Norman "bombed them back to the stone-age" Schwarzkopf get what's coming to you.

Gregory.

I like many people, I am sure,simply like to lurk as threads like this one unfold. Even though I don't contribute to it, I am interested in what all parties have to say on this matter. I actually find it enlightening and at the same time educational. I see also as threads like this progress that people do post things they later regret.

What you have just posted has no place in this thread, it is beneath you and quite frankly appalling. I simply want to say, as somebody who as participated in anti war demonstrations that your opinions on this matter are not constructive. To actually accuse somebody of a war crime on a public forum is quite simply dreadful.Even though I am opposed to war in Iraq, your opinions and views are not reflective of mine or other people I know.

Please, I urge you to take a deep breath, calm down and retract your statements. Equally so I suggest you apologise for making such unfounded and awful accusations.If you will not, then I will do it for you and apologise on behave of myself and the many people I know who genuinely do oppose this war. I will apologies on behave of myself and others who do not feel the need to spit on the backs of the honourable service men and women who risk their lives everyday just so you can accuse them of war crimes.

[SDC]

GregoryUrich... you refer to "Norman 'bombed them back to the stone-age' Schwarzkopf.") I'm not aware that Schwarzkopf said that. I recall it as attributed to Curtis Lemay back in Vietnam war days. From your presentation you evidently believe that Schwarzkopf said it. Please source that.

Seriously. Thanks. Life is hard enough without falsely attributed quotations.

[pomeroo]

Beachnut, before I put you back on ignore, I think it is only fair to respond to your continued personal attacks and misrepresentations.

I signed a petition supporting a group pursuing a new investigation. While I do not agree with everything they are saying, I do feel an investigation is warranted.

You, on the other hand, have been an active participant in the war crimes of Desert Storm contributing to the deaths of 1.5 million Iraqis. Do the so called "militants" hate us for "our freedom" OR DO THEY HATE US BECAUSE WE DESTROYED THEIR COUNTRY AND KILLED THEIR LOVED ONES. There is no question in my mind why you are so hostile to any type of investigation which would examine the possible wrong doings of our government and military. I hope you and Norman "bombed them back to the stone-age" Schwarzkopf get what's coming to you.


Wow! You loony-leftists are up to 1.5 MILLION dead Iraqis now? If you double the absurd, thoroughly debunked estimate of 650,000, you're still a couple of hundred thousand short. In reality, the deaths of 40-70,000 Iraqis, the majority killed by other Iraqis, should not be minimized. But, please try to remember that Saddam is responsible for over a million dead Iraqis, Iranians, Kurds, and Kuwaitis, and you don't care.


* To be fair, a serious study places the death toll at 151,000, a higher figure than I am accustomed to seeing. Your nonsensical fabrication is wrong by a mere factor of ten, and not twenty or thirty.

http://www.washingtonpost.com/wp-dyn/content/article/2008/01/09/AR2008010902793_2.html

[rwguinn]

Beachnut, before I put you back on ignore, I think it is only fair to respond to your continued personal attacks and misrepresentations.

I signed a petition supporting a group pursuing a new investigation. While I do not agree with everything they are saying, I do feel an investigation is warranted.

You, on the other hand, have been an active participant in the war crimes of Desert Storm contributing to the deaths of 1.5 million Iraqis. Do the so called "militants" hate us for "our freedom" OR DO THEY HATE US BECAUSE WE DESTROYED THEIR COUNTRY AND KILLED THEIR LOVED ONES. There is no question in my mind why you are so hostile to any type of investigation which would examine the possible wrong doings of our government and military. I hope you and Norman "bombed them back to the stone-age" Schwarzkopf get what's coming to you.

Your joining that group says you agree with their conclusions--which is why there are very few, if any, actual engineers and scientist subscribers.
As for your rant on the military, you have now fully shown the truther colors.
The ONE defining characteristic of all "troothers" is that they cannot conceive of anyone doing anything for reasons other than fear or money. All the conspirators are afraid to step up, fearing that they might loose their jobs. AAll the victims were paid off, guaranteeing their (continued) silence.Altruism and heroism are foreign concepts. They cannot imagine anyone hating something so much that they are willing to kill themselves and others to rid the world of that something. To them, the US (specifically G. Bush) is the source of all evil in the world, an evil that did not exist anywhere prior to January 2001.
I despair that they will ever join reality, but it's a WoW world for them...

[pomeroo]

Your joining that group says you agree with their conclusions--which is why there are very few, if any, actual engineers and scientist subscribers.
As for your rant on the military, you have now fully shown the truther colors.


The ONE defining characteristic of all "troothers" is that they cannot conceive of anyone doing anything for reasons other than fear or money.


Perfect. Absolutely, completely, 100% dead-on correct! Bullseye, RW!




All the conspirators are afraid to step up, fearing that they might loose their jobs. AAll the victims were paid off, guaranteeing their (continued) silence.Altruism and heroism are foreign concepts. They cannot imagine anyone hating something so much that they are willing to kill themselves and others to rid the world of that something. To them, the US (specifically G. Bush) is the source of all evil in the world, an evil that did not exist anywhere prior to January 2001.
I despair that they will ever join reality, but it's a WoW world for them...

[Par]

Beachnut... [y]ou... have been an active participant in the war crimes of Desert Storm...


You seem to be of the opinion that the coalition’s reversing of Saddam’s annexation of Kuwait was nothing short of a war crime. Is this really what you believe?

[R.Mackey]

Ah, politics, the death of many a scientific inquiry...

I would humbly submit to the membership that it is possible for Gregory's mathematics to be correct, and his motivation to investigate benign, independent of his accuracy in estimating casualties or appreciation of the fine points of international law.

Some of the attacks against him are mean-spirited. It would have been better, Gregory, to respond in Politics, or even not at all, but I can't entirely blame you because I don't think you started it this time.

Follow-ups to Politics. There are a lot of strong feelings on W and the Iraq War in general. Let's not conflate them all, please?

[Par]

Ah, politics, the death of many a scientific inquiry...


I was merely taken aback by what I found to be a rather alarming remark. But you’re quite right. I shouldn’t have contributed to derailing the thread.

[applecorped]

Deep44 - where'd you go? Give up? Give in? Another post and run.

[jaydeehess]

Ah, politics, the death of many a scientific inquiry...

I would humbly submit to the membership that it is possible for Gregory's mathematics to be correct, and his motivation to investigate benign, independent of his accuracy in estimating casualties or appreciation of the fine points of international law.

Some of the attacks against him are mean-spirited. It would have been better, Gregory, to respond in Politics, or even not at all, but I can't entirely blame you because I don't think you started it this time.

Follow-ups to Politics. There are a lot of strong feelings on W and the Iraq War in general. Let's not conflate them all, please?

Here, here..
well said.
We bash the CIT and pft for either not bothering to do the math or getting it wrong. Let's keep the political statements separate from the technical.

[jaydeehess]

Getting back to GU's priginal air expulsion work, my contention is that there is a lot of exit area for the air, not only the lower floors of the south face where much of the glass is missing as well as some perimeter columns, but also the hole through the center of the building. At the very least there is a hole extending from the roof, approx at the center of the east penthouse, to the level of the original column failure(thought to be below the 13th floor and possibly at the 11th) or even down to the 5th or 7th (if indeed the mass falling through the column failure hole and from roof level broke through and smashed the braced trusses at 5 & 7).

Furthermore, a core failure that occured at the 5th or 7th floor would have the mass of 40 stories above the transfer beams over the Con-ed building, moving as one. This is observed to have occured the north face , west of the kink, is over the Con-ed building and does move all at he same time. So the PE of that mass is driving the air out of the lower floor volume. Yes this would offer some resistance but as an analogy, how much resistance, due to the pushing out of the air,do you feel when stepping on an empty plastic pop bottle with its top removed?

If the force (basically a friction force) exerted against the falling mass is than 10% of the gravitational force of the 40 storeys above the 7th floor and remained so for the entire time that the crush through the lower 7 floors occured then total force would be 90% of the gravitational mass above the 7th floor and thus so would be the acelleration be 0.9 g.

At 0.9 g acelleration the time it would take to crush through the first 7 floors would be 1.054 that of the time it would take without that upward, friction force.
A fall from 84 feet with no resistance would take 2.3 seconds. A fall at 90% 'g' would take 2.4 seconds. So it would be , to the naked eye, indistinquishable from free fall.
That is the initial fall of the north face if my senario is correct. At the time then that the 8th floor level reachs the ground it would already be travelling (being very conservative) 65 feet per second and the kinetic energy of the moving mass of the upper falling mass would be proportional to the square of that velocity. Furthermore the structure is severely weakened now, it has lost the support of the core and has fractured east of the center of its long axis. It is basically in three large pieces and each of those pieces is tilted off vertical one way or another (mostly towards the center of the structure). Again then, the available forces for destruction,is going to be comapritively much larger than the resistive ability of the connections between structural members. Again the difference in time of collapse and time of a free fall is going to be small.

How did the building stand then?
The intact building of course had all columns and structural systems intact and at full strength. The structure then lost these in a sequence of events over a period of several hours, each of which contributed to the end result of a structure with no ability to stay upright. The first of these events being the impact of WTC 1 debris

[Oxigen]

GregoryUrich,
I agree with R. Mackey. Don't abandon this thread because of a few mean-spirited individuals. Putting Lashl and Beachnut on ignore will spare us all and probably you from their boring diatribes.

[DGM]

I just want to say that I'm interested in where his calculations are headed.
WTC 7 did in fact show by the physical evidence that there was very little "extra" energy.

Gregory; As I said before I am interested in discussing your calculations after you have a moment to recalculate for assumptions you said you did not consider.

I hope you will consider this to be a genuine offer considering that I don't believe I have ever attacked you on a personal level.

[GregoryUrich]

That is a very strong statement to make against someone, and it is a stupid accusation at that. If Desert Storm is a war crime than it would be one committed under the auspices of the U.N. Security Council and NATO.

What is implied to me by that statement is that you hate the military. I don't like the military either, but that is in a general "I don't believe in killing" sort of way. Your statement, though, is more along the line of hating everyone in the military personally.

That and I don't like the "I hope you and Norman "bombed them back to the stone-age" Schwarzkopf get what's coming to you." statement you made. So while I may be new here, I will report it the next time it happens. Because such a statement is the intellectual equivalent of telling someone to go to hell or **** off. It has no place in a forum debate. OR worse, implying that your opponent should have an act of violence visited upon them. The issue is that the phrase "whats voming to you" is a vague and can mean anything, and since you are refering to war crimes, the inference is that violence is that "what's" in the statement.

Accusing someone in a forum of a crime, without any evidence, is a personal attack; one that weakens your position.

Beachnut has stated on another that he was involved in the sorties to the extent that he saw the lists of targets. You should do some research on the Geneva Convention and on the targets if you don't think war crimes were committed during Desert Storm. Jail is what I had in mind.

No, I don't hate the everyone in the military. I don't even hate war criminals. Nonetheless, if they don't get what's coming to them they, and their kind will continue to perpetrate atrocities.

[GregoryUrich]

I just want to say that I'm interested in where his calculations are headed.
WTC 7 did in fact show by the physical evidence that there was very little "extra" energy.

Gregory; As I said before I am interested in discussing your calculations after you have a moment to recalculate for assumptions you said you did not consider.

I hope you will consider this to be a genuine offer considering that I don't believe I have ever attacked you on a personal level.

I'll try to get to it tomorrow. I haven't interpreted any of your posts as hostile. Anyway, I can take a little badgering but I was reacting to a constant persecution that the moderators have done nothing about.

[GregoryUrich]

GregoryUrich... you refer to "Norman 'bombed them back to the stone-age' Schwarzkopf.") I'm not aware that Schwarzkopf said that. I recall it as attributed to Curtis Lemay back in Vietnam war days. From your presentation you evidently believe that Schwarzkopf said it. Please source that.

Seriously. Thanks. Life is hard enough without falsely attributed quotations.

Actually I did think that quote was attributed to Schwarzkopf. Apparently it wasn't his words. I still think it would be an appropriate middle name though because that's what we/they did. Most people aren't aware of the extent to which we hit basic life supporting infrastructure in Desert Storm.

[DGM]

I'll try to get to it tomorrow. I haven't interpreted any of your posts as hostile. Anyway, I can take a little badgering but I was reacting to a constant persecution that the moderators have done nothing about.
I'll give you that but, I was not all that fond of the (as I see it) reactionary/inappropriate comment in your last post (#166).

[GregoryUrich]

Wow! You loony-leftists are up to 1.5 MILLION dead Iraqis now? If you double the absurd, thoroughly debunked estimate of 650,000, you're still a couple of hundred thousand short. In reality, the deaths of 40-70,000 Iraqis, the majority killed by other Iraqis, should not be minimized. But, please try to remember that Saddam is responsible for over a million dead Iraqis, Iranians, Kurds, and Kuwaitis, and you don't care.


* To be fair, a serious study places the death toll at 151,000, a higher figure than I am accustomed to seeing. Your nonsensical fabrication is wrong by a mere factor of ten, and not twenty or thirty.

http://www.washingtonpost.com/wp-dyn/content/article/2008/01/09/AR2008010902793_2.html

UN numbers for deaths caused by Desert Storm + sanctions. Your apparent misunderstanding smacks of straw old man.

[DGM]

UN numbers for deaths caused by Desert Storm + sanctions. Your apparent misunderstanding smacks of straw old man.
Gregory:
Why don't you just drop it and take the high ground in this peeing contest? Or are you going for who has the best penmanship?

[stateofgrace]

Actually I did think that quote was attributed to Schwarzkopf. Apparently it wasn't his words. I still think it would be an appropriate middle name though because that's what we/they did. Most people aren't aware of the extent to which we hit basic life supporting infrastructure in Desert Storm.

I think you will find that most people are fully aware of the extend and most people are also aware of the crippling sanctions that were imposed on Iraq.

Please do not try to underestimate peoples abilities to grasp historical fact and please do not underestimate peoples ability to understand them

Gregory, my post to you was hostile, I admit, simply because you have politicised this issue. You have dragged into this debate the entire Iraq issue. You have accused members of this forum of being war criminals.

I would ask you again to reconsider what you are saying; retract your statements and apologise.Please do so.To me this simply smacks of you demonising individuals who do not agree with you and worse using the Iraq war to do so.

I have nothing further to say to you. Get your own thread back on topic and stop further fuelling the fire.

[beachnut]

Ah, politics, the death of many a scientific inquiry...

I would humbly submit to the membership that it is possible for Gregory's mathematics to be correct, and his motivation to investigate benign, independent of his accuracy in estimating casualties or appreciation of the fine points of international law.

Some of the attacks against him are mean-spirited. It would have been better, Gregory, to respond in Politics, or even not at all, but I can't entirely blame you because I don't think you started it this time.

Follow-ups to Politics. There are a lot of strong feelings on W and the Iraq War in general. Let's not conflate them all, please?
I screwed up, and read that petitions again; where Greg signed and blames Americans for 9/11. I find it ironic as Greg tries now to back in the "ample evidence" with this thread, when he already has "ample evidence". I never was a drone, I think WHY is important, and suspect Greg's on the job training by people like you with foil his WHY as he becomes educated by those who post here.

Knowledge is not served well by politics; I agree. This is why I have a problem with Greg veiling his political goals behind the guise of knowledge, when it looks like he is just searching for that "ample evidence" he already has.

I wish it made sense; but researching a person's goal and why they are doing something has always helped me find racist, liars, and people who try to spread doubt with false information. I am not surprised why Greg pursues certain issues while he lacks the engineering tools and time to do so.

I am optimistic, with your help and other intelligent posters here, Greg can learn enough to see how 19 terrorist used very simple means to kill Americans as promised by UBL a long time ago.

Bring on the numbers; an education is in the works.

[Oxigen]

[QUOTE=GregoryUrich;3583904]My bad. I should have called the derail earlier. My terse reply was in reaction to your insulting approach which attempts to characterize me as a do nothing whiner. I think I have demonstrated my commitment to doing evidence based research and your attack is completely unwarranted.

This insulting approach is typical of Lashl. Can the moderators do something about this.

[twinstead]

Bringing politics into a scientific discussion certainly does NOT rock.

[GregoryUrich]

I think you will find that most people are fully aware of the extend and most people are also aware of the crippling sanctions that were imposed on Iraq.

Please do not try to underestimate peoples abilities to grasp historical fact and please do not underestimate peoples ability to understand them

Gregory, my post to you was hostile, I admit, simply because you have politicised this issue. You have dragged into this debate the entire Iraq issue. You have accused members of this forum of being war criminals.

I would ask you again to reconsider what you are saying; retract your statements and apologies.Please do so.To me this simply smacks of you demonising individuals who do not agree with you and worse using the Iraq war to do so.

I have nothing further to say to you. Get your own thread back on topic and stop further fuelling the fire.

Most of the people on this thread disagree with me and I have not demonized them or even been sarcastic. If you have followed my posts at all, you know I dont just start running people down regardless of their beliefs or arguments.

I have accused one person of being a war criminal based on his own description of his responsiblities during Desert Storm. He has stated that he would rather be a war criminal than a truther and I take that as a tacit admission of guilt.

Look, I didn't start this sh*t. Beachnut has been continually harassing me, falsely representing my work and accusing me of lying. Beachnut is calling me a truther = worse than war criminal. How much BS am I supposed to put up with?

My apologies to everyone for the derail.

[Oxigen]

Most of the people on this thread disagree with me and I have not demonized them or even been sarcastic.

Look, I didn't start this sh*t. Beachnut has been continually harassing me, falsely representing my work and accusing me of lying. Beachnut has stated that he would rather be a war criminal than a truther and he is calling me a truther = worse than war criminal.

My apologies to everyone else for the derail.

Just put him on ignore. He is a distraction to science.

[DGM]

Bringing politics into a scientific discussion certainly does NOT rock.
Amen to that.

[beachnut]

Most of the people on this thread disagree with me and I have not demonized them or even been sarcastic.

Look, I didn't start this sh*t. Beachnut has been continually harassing me, falsely representing my work and accusing me of lying. Beachnut has stated that he would rather be a war criminal than a truther and he is calling me a truther = worse than war criminal.

My apologies to everyone else for the derail.
Your apology accepted. Now get back to finding that "ample evidence"; never too late.

Back to WTC7 revisited…

[stateofgrace]

Most of the people on this thread disagree with me and I have not demonized them or even been sarcastic. If you have followed my posts at all, you know I dont just start running people down regardless of their beliefs or arguments.

I have accused one person of being a war criminal based on his own description of his responsiblities during Desert Storm. He has stated that he would rather be a war criminal than a truther and I take that as a tacit admission of guilt.

Look, I didn't start this sh*t. Beachnut has been continually harassing me, falsely representing my work and accusing me of lying. Beachnut is calling me a truther = worse than war criminal. How much BS am I supposed to put up with?

My apologies to everyone for the derail.

Your accusations are irrelevant and without foundation and are dismissed as such.

I say this in the spirit of friendship and hope you will take it as such but do yourself a favour do not pretend to lecture me or anybody else about the injustices on this planet. Don't start throwing figures about the death toll in the Middle East nor the effects of the economic sanctions and presume to think that I or anybody else is blissfully unaware. We are all aware; we all fully understand and do not need to be told by you.

I suggest you keep out of this arena in future, state your case, put forward your facts and calculations but do not ever kid yourself that the reason you are subject to "BS" is because grown adults are simply unable to see what is so blindingly obvious to you and you alone.

Your apology is accepted in the same spirit.Now get your thread back on topic.

[pomeroo]

UN numbers for deaths caused by Desert Storm + sanctions. Your apparent misunderstanding smacks of straw old man.


Ah, yes, MY misunderstanding. Of course, Saddam was guilty of nothing when he invaded a sovereign state. Alleged deaths attributable to the U.N. sanctions are American war crimes. Anti-Americanism, like its close relation anti-Semitism, is a strange disease.

[GregoryUrich]

Your accusations are irrelevant and without foundation and are dismissed as such.

I say this in the spirit of friendship and hope you will take it as such but do yourself a favour do not pretend to lecture me or anybody else about the injustices on this planet. Don't start throwing figures about the death toll in the Middle East nor the effects of the economic sanctions and presume to think that I or anybody else is blissfully unaware. We are all aware; we all fully understand and do not need to be told by you.

I suggest you keep out of this arena in future, state your case, put forward your facts and calculations but do not ever kid yourself that the reason you are subject to "BS" is because grown adults are simply unable to see what is so blindingly obvious to you and you alone.

Your apology is accepted in the same spirit.Now get your thread back on topic.

What is it that is so blindingly obvious to me and me alone?

[jaydeehess]

There is a politics section guys.

[stateofgrace]

What is it that is so blindingly obvious to me and me alone?

I did initially prepare a lengthy reply to your question but upon reflection have decided against posting it.I will acknowledge other members requests to no longer politicise and derail his thread. I will leave this thread and in doing so again request you reconsider your accusations and withdraw them.

Please do not take this a dodge; it is simply an acknowledgement that to continue a political pissing contest in this thread is not wanted. As such please get your thread back on topic, that being WTC 7.

[Chuck Guiteau]

This particular debate seems to take up a lot of bandwidth, both here and on other sites, and I don't understand why.
If a building falls because the load bearing structures failed from fire or damage, or if they fail due to a CD, the building is still going to fall at the same rate, unless whoever is performing the CD wants to blow virtualy every support structure in the building, and doing that doesn't make sense.

I'm not a physics major, or even particularly good at math, but I do have experience with explosives and the techniques of controlled demolitions, and the purpose of a Cd is not to make the building fall faster, it's just to make the building fall ( in a controlled manner so as to minimize demolition/removal expenses).

CD's are planned to remove just enough of the load bearing structures to initiate collapse; this minimizes both the work involved, the time necessary, and the costs involved. Anything else ( such as blowing large enough numbers of load bearing structures to make any appreciable difference in collapse times) is wastefull and pointless. I would think that if it were to be performed in a clandestine manner it would be even more pointless, as it would leave additional detritus that would provide evidence of the act.

So can someone please tell me what the ballyhoo is about?

[GregoryUrich]

This particular debate seems to take up a lot of bandwidth, both here and on other sites, and I don't understand why.
If a building falls because the load bearing structures failed from fire or damage, or if they fail due to a CD, the building is still going to fall at the same rate, unless whoever is performing the CD wants to blow virtualy every support structure in the building, and doing that doesn't make sense.

I'm not a physics major, or even particularly good at math, but I do have experience with explosives and the techniques of controlled demolitions, and the purpose of a Cd is not to make the building fall faster, it's just to make the building fall ( in a controlled manner so as to minimize demolition/removal expenses).

CD's are planned to remove just enough of the load bearing structures to initiate collapse; this minimizes both the work involved, the time necessary, and the costs involved. Anything else ( such as blowing large enough numbers of load bearing structures to make any appreciable difference in collapse times) is wastefull and pointless. I would think that if it were to be performed in a clandestine manner it would be even more pointless, as it would leave additional detritus that would provide evidence of the act.

So can someone please tell me what the ballyhoo is about?

What you are saying makes sense, but I'm not sure you are entirely correct. While I have no experience with CD, I do understand that normal CD's sever way more structural members than is necessary in order to assure a neat and safe collapse. This can be seen in numerous videos on line where there are explosions throughout the building when all that is necessary is to blow the lowest columns.

How much this would affect the fall time is another question which is compounded by the inaccuracies inherent in the modelling. Nonetheless, I believe I have come far enough with WTC1 and 2 to demonstrate that CD was very unlikely. I am working within the truth movement to spread this knowledge. Contrary to most opinions here, some truthers are actually interested in the truth. I am hoping I can bring the same level of proof to WTC7 regardless of what the conclusion may be.

[GregoryUrich]

I want to discuss two different topics, namely the air pressurization, and the effective strength of the remaining structure. Let me also say that some of the slings and arrows aimed at Gregory appear unearned. There is an opportunity to learn from this, guys...

Quote cut for brevity. See the rest of Ryan's post here (http://forums.randi.org/showthread.php?postid=3565678#post3565678).

I have adjusted my calculation to the actual floor area and shape of the building. I get 16.5 GJ to expel air by the same method. This is still higher than the actual energy expended which is around 14 GJ. It is important to remember that I am not taking aperature or compression into account, only inertia. Thus there is no restriction to the air flowing out of the building so broken windows or missing facade are not an issue.

To refine this further, it would be necessary to estimate any internal damage and also the amount of floor openings due to elevators and such which would reduce the floor area. I would appreciate any opinions on upper and lower bounds for these.

Responses to Ryan:

#1. I'm not sure I agree that there is no cost to get the air moving. The air is not moving relative to it's compartment. I agree that it will have momentum and as the lower floor of the compartment is decellerated during impact there will be some pressure caused by the decelleration of the air as well but I think that this will be negligible compared to the pressure caused by the compaction of the compartment.

#2. In order to arrive at the expended energy during collapse. I am removing energy interatively in "jerks" at each floor impact such that the fall time becomes 6.5 sec. My interpretation of "very little structural resistance" is based on the air resistance accounting for all resistance rather than the comparatively low total energy dissipated during collapse which is expected in a bottom up collapse.

#3. Dr. Greening has pointed out previously that adiabatic heating can be a significant energy factor. Have you taken this into account in your more "pressure oriented" method?

#4. Agreed.

#5. At this level of refinement, I would caution the truth movement not to jump up and down crying CD is proven. There are still a lot of factors that have not been taken into account.

[beachnut]

What you are saying makes sense, but I'm not sure you are entirely correct. While I have no experience with CD, I do understand that normal CD's sever way more structural members than is necessary in order to assure a neat and safe collapse. This can be seen in numerous videos on line where there are explosions throughout the building when all that is necessary is to blow the lowest columns.

How much this would affect the fall time is another question which is compounded by the inaccuracies inherent in the modelling. Nonetheless, I believe I have come far enough with WTC1 and 2 to demonstrate that CD was very unlikely. I am working within the truth movement to spread this knowledge. Contrary to most opinions here, some truthers are actually interested in the truth. I am hoping I can bring the same level of proof to WTC7 regardless of what the conclusion may be.
Oh, you joined the guys with the "ample evidence" to tell them they are wrong? So we the people did not do it to our selves, 19 terrorist did it and CD is a fantasy along with thermite of Jones (who made it up 4 years out of the blue after 9/11 because he is anti-war, but would rather attack others politically). Have you told them yet they are missing the "ample evidence".

Yep, I joined the NAZIs to tell them they were wrong; You can not hang me for that. lol; you are one not so truthful truther.

You better get back to learning how things work, with help from the guys here who help you learn. Back to WTC7 revisited, the smoking gun many a time for the 9/11 truth movement.

[DGM]

Gregory:
What have you used for the end point (lack of better word) of the collapse? What I'm referring to is the building unlike the towers was not completely demolished (large section of the north face laid over the pile). The collapse (by looking at the photos of the debris pile) seamed to die out toward the end. The building was also falling over instead of straight down. Some pictures of the pile,ect
http://www.debunking911.com/pull.htm

I'm wondering how much this would figure into you equations?

[GregoryUrich]

Gregory:
What have you used for the end point (lack of better word) of the collapse? What I'm referring to is the building unlike the towers was not completely demolished (large section of the north face laid over the pile). The collapse (by looking at the photos of the debris pile) seamed to die out toward the end. The building was also falling over instead of straight down. Some pictures of the pile,ect
http://www.debunking911.com/pull.htm

I'm wondering how much this would figure into you equations?

I'm calculating from the roof to the ground. The building up of the pile would have reduced the effective PE somewhat. I don't think it would be significant in terms of air expulsion since it builds up gradually.

[DGM]

I'm calculating from the roof to the ground. The building up of the pile would have reduced the effective PE somewhat. I don't think it would be significant in terms of air expulsion since it builds up gradually.
Thanks, I'm curious to see Ryan's reply to your response. The "pressurization" (#1) has me wondering. Like I said before I don't see any large (sudden) releases of air that would lead me to believe that the building was capable of holding much pressure back (lots of damage) unlike the towers.

[GregoryUrich]

Thanks, I'm curious to see Ryan's reply to your response. The "pressurization" (#1) has me wondering. Like I said before I don't see any large (sudden) releases of air that would lead me to believe that the building was capable of holding much pressure back (lots of damage) unlike the towers.

I don't think the building was highly pressurized. As the bottom most floor collapses the floors come together the air gets pushed out. This happened successively for each floor from the bottom up and was driving the dust clouds. The dust clouds can be observed billowing outward at significant speeds from very low down.

[Jonnyclueless]

Gregory, I have seen videos on youtube where only the bottom supports were knocked out an the building didn't collapse, just the bottom floor came out and the rest of the building managed to stand. Hopefully the demolition crew didn't get paid in those cases. I think the videos were posted as humor, but your post reminded me of them.

I think its safe to say that they remove all the support points because it's the only way they can guarantee a total collapse.

[jaydeehess]

Quote cut for brevity. See the rest of Ryan's post here (http://forums.randi.org/showthread.php?postid=3565678#post3565678).

I have adjusted my calculation to the actual floor area and shape of the building. I get 16.5 GJ to expel air by the same method. This is still higher than the actual energy expended which is around 14 GJ. It is important to remember that I am not taking aperature or compression into account, only inertia. Thus there is no restriction to the air flowing out of the building so broken windows or missing facade are not an issue.

To refine this further, it would be necessary to estimate any internal damage and also the amount of floor openings due to elevators and such which would reduce the floor area. I would appreciate any opinions on upper and lower bounds for these.
.

Try removing the core of the building bounded by columns 58,59,60 to the east and 76,77,78 to the west as already having failed and collapsed. This area was partially intact at roof level as the north wall begins moving but we can operate on the assumption that all was missing (or at least already moving and having expelled most of the air in that volume under the roof) below the roofline in that area by the time the north wall begins moving.

Roughly speaking it reduces the floor area of all floors by about 25%.

[R.Mackey]

#1. I'm not sure I agree that there is no cost to get the air moving. The air is not moving relative to it's compartment. I agree that it will have momentum and as the lower floor of the compartment is decellerated during impact there will be some pressure caused by the decelleration of the air as well but I think that this will be negligible compared to the pressure caused by the compaction of the compartment.

The reason there's no cost to get the air moving is because it too has gravitational potential -- on the order of 0.7 GJ if I didn't slip an order of magnitude. This is the same reason a sealed box full of air falls at the same rate as a box full of vacuum, corrected for mass, in a freestream.

As that air is expelled and "turns the corner" against the ground, there is a local felt pressure by the ground (dynamic pressure), but the pressure at the descending "piston" is the same. Incompressible flow. From the "piston"'s perspective, the streamlines haven't changed. It doesn't know about the air turning ahead of it.

What backpressure you get, again, will be primarily due to Venturi effect (the remainder being turbulence, etc.).


#2. In order to arrive at the expended energy during collapse. I am removing energy interatively in "jerks" at each floor impact such that the fall time becomes 6.5 sec. My interpretation of "very little structural resistance" is based on the air resistance accounting for all resistance rather than the comparatively low total energy dissipated during collapse which is expected in a bottom up collapse.

The "jerks" aren't quite the same thing as your spreadsheet -- you're summing up in a Riemann fashion rather than a continuous integral, which is perfectly adequate for this estimate. What I mean is that the total work done against the air is much higher than it might seem because the backpressure applies over the entire height of collapse, whereas the structural elements apply only over a small fraction, equal to or less than the yield strain of the materials, or ~3%.


#3. Dr. Greening has pointed out previously that adiabatic heating can be a significant energy factor. Have you taken this into account in your more "pressure oriented" method?

I did not, simply because "adiabatic," among other things, means "reversible." The heating is a temporary cost. When the air escapes the structure, that heat will be returned as kinetic energy, minus some small correction of course since our system and our gas aren't ideal.

While the energy loss to heating will be very small, we can also bound it by computing the heating during pressurization. Suppose our structure withstands 1 PSI of overpressure before it starts breaking windows all over, so 1 PSI is our self-regulating backpressure. In adiabatic compression, we have the following equation of state:

p Vγ = constant (1)

where γ = 1.4 for air. We also will need the Ideal Gas Law:

p V = n R T (2)

So let State 1 be the air in WTC 7 before compression, and State 2 be the air after compression. For sake of argument, assume State 1 is STP -- yes, I know the fire would have heated the air, but ignore that for now; it doesn't make that much difference here. We've already decided that p2 = 16 PSI, or p2 / p1 = 16/15. From Eq. (1), we can then calculate the relative volumes, and we find:

V2 / V1 = (p1 / p2) (1/γ) = 0.95.

Next, we find the resulting increase in temperature by writing the ideal gas law for both State 1 and State 2, and then dividing both equations, to get:

(p2 V2 / p1 V1) = T2 / T1 (3)

and thus T2 / T1 = 1.02. Since above we assumed that T1 = 300 K, we find that the compression causes a rise of about six Kelvins in the temperature.

Now we can estimate the energy content as a result using the specific heat of air. At this point we have to make a decision based on our method of estimation -- under the adiabatic model, there is no heat entering or leaving, so this equation doesn't strictly exist. We're highballing it. We can choose instead to use either the specific heat under constant pressure (CP) or constant volume (CV), but neither is strictly appropriate. I've chosen to go with CV, modeling that the air will be expelled as it is and only then expand, thus carrying away the maximum amount of energy as it does so.

Under this assumption, the energy content from heating is as follows:

ΔH = ρ V N CV ΔT (4)

where ρ is the density of air (and hence ρ V is the total mass of air); N is the molar mass of air, approximately 29 g/mol; and CV is the specific heat under constant volume, 20 J / mol K. I roughly estimate the air mass at 850 tonnes, assuming a footprint of 3900 m2 and 180 m height. This gives us the maximum energy loss possible due to heating:

ΔH = 3.5 GJ

This is about 40% of the energy expended against the backpressure that I computed before. Since that estimate is sensitive to the actual backpressure seen in the building, which could be +/- 100%, this result is not particularly significant. Remember that this is the worst case loss to adiabatic heating, and the expected value is closer to zero. I think this will be lost in the noise.

Again, this calculation supposes the building only withstands 1 PSI of overpressure before the air finds another way out. That number is going to be very, very hard to estimate, and the result is strongly dependent upon it.

#5. At this level of refinement, I would caution the truth movement not to jump up and down crying CD is proven. There are still a lot of factors that have not been taken into account.

The other big uncertainty in the problem is the actual energy dissipated during collapse. Since you've estimated a collapse time very close to "freefall," your calculation will be maximally sensitive to small errors in the timing. An underestimate of only 0.5 seconds, for instance, means about another 14% of the total gravitational potential was actually consumed, or about 13 GJ additional energy. As a result, your error bars on the energy available are going to be large -- I'd estimate +/- 100% -- unless you can estimate the collapse time very accurately. I can't.

At the end of the day, if we could sum up all of the energies properly, I would expect to find the following:

Ebuilding = 14 GJ +/- 10
+ Eair = 7 GJ +/- 10
= Etotal = 20 GJ +/- 10

Something like that. The uncertainties are so high that I doubt we will ever conclude one way or the other.

What you can conclude, however, is the following:

The energy budget is rather tight
The energy expenditure against the air is much higher than most people would expect, possibly higher than the destruction energy of the structure during collapse
The speed of collapse suggests, but does not definitively prove, that the structure suffered very heavy internal damage prior to total collapse
I'll be interested to see how the third conclusion tracks against NIST's final report. We know they'll propose that an internal failure triggered the collapse. This investigation suggests that the internal failure was very widespread -- this investigation seems to conflict with a finding that the failure was only on one floor. I'm expecting to see a nearly total core failure leading the collapse after having walked through this derivation.

[Chuck Guiteau]

What you are saying makes sense, but I'm not sure you are entirely correct. While I have no experience with CD, I do understand that normal CD's sever way more structural members than is necessary in order to assure a neat and safe collapse. This can be seen in numerous videos on line where there are explosions throughout the building when all that is necessary is to blow the lowest columns.

How much this would affect the fall time is another question which is compounded by the inaccuracies inherent in the modelling. Nonetheless, I believe I have come far enough with WTC1 and 2 to demonstrate that CD was very unlikely. I am working within the truth movement to spread this knowledge. Contrary to most opinions here, some truthers are actually interested in the truth. I am hoping I can bring the same level of proof to WTC7 regardless of what the conclusion may be.
Sorry about the delay in response, but during the week I'm not able to access the Internet.
The secondary explosions you are referring to have nothing to do with making the structure collapse, their purpose is to assure that the debris is broken into managable sized pieces, making removal easier.
Again, unless someone is willing to blow virtually every load bearing structure in a building simultaneously, collapse time would not be meaningfully different.
As an aside, someone else here mentioned buildings which failed to fall after the support structures were blown. This happens, but is almost always the product of a bad shot, where some of the charges fail to detonate.

Here's an idea:
Instead of looking for vidoes of CD's then comparing them to the WTC videos, why don't you search for some videos of buildings collapsing from known fire/impact/etc., then compare those collapse times with the known CD's ( using buildings of similar construction)?

[GregoryUrich]

Sorry about the delay in response, but during the week I'm not able to access the Internet.
The secondary explosions you are referring to have nothing to do with making the structure collapse, their purpose is to assure that the debris is broken into managable sized pieces, making removal easier.
Again, unless someone is willing to blow virtually every load bearing structure in a building simultaneously, collapse time would not be meaningfully different.
As an aside, someone else here mentioned buildings which failed to fall after the support structures were blown. This happens, but is almost always the product of a bad shot, where some of the charges fail to detonate.

Here's an idea:
Instead of looking for vidoes of CD's then comparing them to the WTC videos, why don't you search for some videos of buildings collapsing from known fire/impact/etc., then compare those collapse times with the known CD's ( using buildings of similar construction)?

Comparing videos of CD's to the WTC collapse videos has never been my strategy. Maybe you are thinking of someone else. If you are aware of any impact/fire collapses other than WTC, I'm sure everyone would be very interested to know about them.

[GregoryUrich]

The reason there's no cost to get the air moving is because it too has gravitational potential -- on the order of 0.7 GJ if I didn't slip an order of magnitude. This is the same reason a sealed box full of air falls at the same rate as a box full of vacuum, corrected for mass, in a freestream.

As that air is expelled and "turns the corner" against the ground, there is a local felt pressure by the ground (dynamic pressure), but the pressure at the descending "piston" is the same. Incompressible flow. From the "piston"'s perspective, the streamlines haven't changed. It doesn't know about the air turning ahead of it.

What backpressure you get, again, will be primarily due to Venturi effect (the remainder being turbulence, etc.).

I still don't quite get this.

Say the container was open on the sides but did not collapse upon impact. Would the air's momentum be retained in "turning the corner"? (I think we can ignore Bernoulli during the fall because the container wasn't really open.)

In this case I picture the air's momentum causing a pressure differential between the upper and lower parts of the container and that the pressure differential would suck as much air into the upper part as is expelled from the lower part. To get the air out, I would think it needs to be pushed out requiring lateral acceleration.

If the air is incompressible it's also in-decompressible so the air cannot run out of the container such that all momentum/energy would be transferred to the ground/pile.

I have never studied fluids so I am probably missing something.

[R.Mackey]

I still don't quite get this.

Say the container was open on the sides but did not collapse upon impact. Would the air's momentum be retained in "turning the corner"? (I think we can ignore Bernoulli during the fall because the container wasn't really open.)

We can ignore Bernoulli during most of the fall. If we assume the floors are all individually sealed until they actually contact the ground, then the only flow case we need to consider is a single floor, top descending and bottom fixed, where the air "turns the corner."

At this point there will be a slight loss of energy due to the air's inertia, but until then, the air falls as a solid body and expends its own gravitational energy. The air in the 40th story will fall 39 floors, picking up speed, for free, and then only require acceleration for the very last floor. This inertial term will actually decrease with initial height, since acceleration per unit time is roughly constant, therefore acceleration per unit distance will decrease.


In this case I picture the air's momentum causing a pressure differential between the upper and lower parts of the container and that the pressure differential would suck as much air into the upper part as is expelled from the lower part. To get the air out, I would think it needs to be pushed out requiring lateral acceleration.

If the air is incompressible it's also in-decompressible so the air cannot run out of the container such that all momentum/energy would be transferred to the ground/pile.

Right. So what happens is this:
The air at the bottom, in contact with the ground, has its momentum changed.
This results in an equal-and-opposite force at ground level. The air sees this as a change in its velocity. The ground sees this as an increase in pressure ("dynamic pressure," = 1/2 rho v2).
The air that is actually "turning the corner," however, at any given instant, is all in contact with the ground.
Because we're in an incompressible flow situation (until the speed gets very high, e.g. Venturi effect), the average chamber pressure (static pressure) doesn't change. All of the pressure effects are dynamic pressure.
What this means is that, to calculate the actual felt pressure at any point, all you need to know is the fluid velocity.
The fluid velocity at the top of the chamber -- at the descending floor -- is unchanged. The fluid "turning the corner" does not reflect pressure waves or create eddies that move against the flow and up to the descending floor.
As a result, the descending floor sees no meaningful change in pressure, again until the incompressible assumption no longer holds.

It's tricky stuff. You also have large-scale circulation to deal with. There is also ambient air pressure pushing down on the top of the structure the whole time...

[shagster]

It appears that the gash on the south facade of WTC7 was in proximity to the diesel risers. I superimposed the width of the upper level damage shown on a preliminary NIST report onto other diagrams in a NIST report that show the location of the diesel risers which fed various floors.

The risers were near the perimeter of the core area on the south side of the core. The gash was near the same location. Even if the gash didn't completely extend into the core area or was slightly west or east of the risers, the jolting could have been sufficient to sever the lines. This is one possible explanation for fires starting and burning on numerous floors.

One of the preliminary NIST reports on WTC7 refers to damage in the location of the gash, but it is stated as roof and upper level debris damage. Apparently at the time of writing, NIST wasn't aware that the gash extended nearly all the way down the south facade and in nearly the same location as the diesel risers.

http://i134.photobucket.com/albums/q91/shagster31/wtc7/wtc7g.jpg

[shagster]

The gash going all the way down the south facade of WTC7 is an issue that needs to be addressed by NIST and the engineering community. This is a progressive collapse that started with debris impact at the top of the building. It's reminiscent of the Ronan apartment progressive collapse. It shouldn't happen in a properly designed building. The gash indicates that WTC7 was not very robust in terms of its ability to arrest a collapse.

[shagster]

The collapse that occurred on the east side of WTC7 before the global collapse is another indication of the lack of robustness. This partial collapse appears to have started in the region where fires were burning near the 11th and 12th stories. The east side of the building was also the side with the longest span floors. These long span floors apparently failed as a result of the fires and the collapse progressed up to the top of the east side of the building. This indicates again that WTC7 wasn't robust in its ability to resist collapse.

[jammonius]

As NIST hasn't got the foggiest idea what destroyed WTC 7, perhaps some of its staff will get some ideas from this thread.

[Dave Rogers]

As NIST hasn't got the foggiest idea what destroyed WTC 7,

And your evidence for this claim is?

Dave

[DGM]

The gash going all the way down the south facade of WTC7 is an issue that needs to be addressed by NIST and the engineering community. This is a progressive collapse that started with debris impact at the top of the building. It's reminiscent of the Ronan apartment progressive collapse. It shouldn't happen in a properly designed building. The gash indicates that WTC7 was not very robust in terms of its ability to arrest a collapse.
I think your being unfair to the designers and the strength of the building. This building lasted with un-fought fires for 7 hours. Everyone got out. What more would you expect from a building that was exposed to such extraordinary circumstances?

[beachnut]

As NIST hasn't got the foggiest idea what destroyed WTC 7, perhaps some of its staff will get some ideas from this thread.
Wrong. NIST
An initial local failure occurred at the lower floors (below floor 13) of the building due to fire and/or debris-induced structural damage of a critical column (the initiating event) which supported a large-span floor bay with an area of about 2,000 square feet; You are the one with out the foggiest idea; not NIST. So you need to study more. Are you in failure mode?

Fire did it; but you have no clue what their goals for studying the collapse are, do you?

But gee, they are wasting money for the CD nuts, who are lacking knowledge...
While NIST has found no evidence of a blast or controlled demolition event, it is evaluating the magnitude of hypothetical blast scenarios that could have led to the structural failure of one or more critical elements.

You lack knowledge on NIST, why?

You are the one in the fog.

[shagster]

I think your being unfair to the designers and the strength of the building. This building lasted with un-fought fires for 7 hours. Everyone got out. What more would you expect from a building that was exposed to such extraordinary circumstances?

I wouldn't say unfair. These are issues that need to be studied in order to build safer modern metal frame high rises. The collapse that occurred on the east side of the building where fires were burning near the 11th and 12th stories is disturbing. That collapse propagated all the way up to the top of the building. That shouldn't happen in a properly designed building. A fire burning on a couple of adjacent stories isn't extraordinary. That type of collapse could potentially happen solely due to fire on a couple of adjacent stories in other high rises of similar design and that have long span floors. I wouldn't want to be stuck in such a building during a fire or be fighting the fire inside of one.