How could the interior collapse in WTC7 Move West Without More Visible Exterior Damage

John85

Member
[Mod note: thread split from https://www.metabunk.org/how-buckli...ation-for-part-of-wtc7s-collapse.t8270/page-4, some posts have been merged or deleted to simplify the flow of the discussion]

The problem with building 7's free fall is that nobody was stepping on it like a soda can, and there's no way to hollow out the middle of the building quietly and without causing extensive damage to the outside. Before it fell, there were a handful of broken windows, that's it. Pretty much the whole building fell as one, and did so at free fall acceleration for a period of over 2 seconds. Can't be reconciled with collapse by fire. The NIST account doesn't even approach reality. We can all disparage crazy conspiracy theories, but the official account doesn't stand up.

No, that is just incorrect.

There was substantial damage as a result of wreckage from the WTC collapse. There are a few pictures of it before smoke obscured the building.
I'm talking about the lack of damage to the exterior caused by the supposedly-falling interior, not damage that happened 7 hours before collapse. The idea that free fall buckling is possible, the claim of this thread, depends on the exterior being like the wall of a soda can. That means that it has to be a thin tube, the only structure remaining after the building gets hollowed out. We can see that this view is false, because it is not possible for the middle of the building to hollow itself out, leaving just a few broken windows on the exterior. The NIST account wants us to believe that after column 79 failed, a sequence of floor failures traveled right to the top of the building, and then column failures propagated west, as falling girders took out beams and girders next to them on the way down, causing neighboring columns to become unsupported, then buckle. If falling floors are capable of propagating damage west, they would also take out bits and pieces of the external frame to the north, east and south. Even the broken windows that we can see do not have falling concrete, beams, furniture or the like flying out of them. That shows that buckling of the exterior moment frame only is not what we saw in that 2 seconds of free fall.
 
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Jeffrey Orling

Senior Member
I see how you've misinterpreted my post. I'm talking about the lack of damage to the exterior caused by the supposedly-falling interior, not damage that happened 7 hours before collapse. The idea that free fall buckling is possible, the claim of this thread, depends on the exterior being like the wall of a soda can. That means that it has to be a thin tube, the only structure remaining after the building gets hollowed out. We can see that this view is false, because it is not possible for the middle of the building to hollow itself out, leaving just a few broken windows on the exterior. The NIST account wants us to believe that after column 79 failed, a sequence of floor failures traveled right to the top of the building, and then column failures propagated west, as falling girders took out beams and girders next to them on the way down, causing neighboring columns to become unsupported, then buckle. If falling floors are capable of propagating damage west, they would also take out bits and pieces of the external frame to the north, east and south. Even the broken windows that we can see do not have falling concrete, beams, furniture or the like flying out of them. That shows that buckling of the exterior moment frame only is not what we saw in that 2 seconds of free fall.
The exterior of 7wtc was a moment frame..a rigid trapezoid. The interior collapsed down inside before the facade came down and when it did it rotated anticlockwise and was kinked There were only 26 columns below the facade which were axially coupled to the foundation... 57 above. The belt trusses acted like beams at the lower end of the facade... above floor 5. The 26 columns were pulled in by the beams and girders connected the transfer structures and a few columns such as 79,80 and 81.

As with the twin towers the floor collapse did no damage other than breaking windows when the floors collapsed inside it.
 

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Jedo

Member
I see how you've misinterpreted my post. I'm talking about the lack of damage to the exterior caused by the supposedly-falling interior, not damage that happened 7 hours before collapse. The idea that free fall buckling is possible, the claim of this thread, depends on the exterior being like the wall of a soda can.
Well I guess @Mick West just wanted to demonstrate the effect how much weight a soda can support before buckling. Btw the ratio of the walls of a soda can to its diameter is approximately 50 times smaller than the ratio of largest transversal dimension of the outer columns compared to the width of WTC7. The phenomena of buckling still applies, though. Actually it is a major concern in structural engineering of high-rise buildings, see any textbook on that topic.
That means that it has to be a thin tube, the only structure remaining after the building gets hollowed out.
No, the maximum load a column can bear before buckling goes with the inverse square of its length. Even if the engineers constructed the columns with a safety factor of 50 for buckling, a loss of lateral support for 8 stories gives the column only 1/64 of its resistance to buckling.
We can see that this view is false, because it is not possible for the middle of the building to hollow itself out, leaving just a few broken windows on the exterior.
How then do you explain the collapse of the East Penthouse which wasn't accompanied by any window breaking but by a travelling pressure wave?
The NIST account wants us to believe that after column 79 failed, a sequence of floor failures traveled right to the top of the building, and then column failures propagated west, as falling girders took out beams and girders next to them on the way down, causing neighboring columns to become unsupported, then buckle.
NIST did also a study where they took out column 79 for two stories only, and also got a complete collapse of the building. So they looked at the controlled demolition theory, and showed that it is feasible to destroy the building with only having charges at a single column. However, they studied also the effects what this minimal setup for controlled demolition, like 1kg of high explosives, would be in terms of the shockwave this explosion would produce. They found that windows would certainly break due to the shockwave, and that the blast sound would be approx. 130-140dB in something like half a mile distance. Neither evidence of the impact of glass shrapnel on neighbouring buildings nor that of explosion sounds that loud have been reported.
If falling floors are capable of propagating damage west, they would also take out bits and pieces of the external frame to the north, east and south.
Well, that depends on the actual stress in each element of the construction, and on the actual strength of the connections. As far as I know the connections between elements of the outer frame are made to withstand large stress in the plane of the frame, while the connections from the frame to the floor where constructed mainly for vertical load. So it is quite likely that the connections perpendicular break due to higher horizontal loads than they where constructed to bear, while the frame holds together as one piece.
Even the broken windows that we can see do not have falling concrete, beams, furniture or the like flying out of them. That shows that buckling of the exterior moment frame only is not what we saw in that 2 seconds of free fall.
Why should furniture fly out when the interior collapses? collapse.png
As you can see on the second image, in an internal collapse any furniture would rather tend to move inwards. Contrast this with the case of an explosion, where the shockwave would move stuff outwards. So the absence of windows breaking and furniture flying out of the building would be rather evidence against controlled demolition rather than for it.
 
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MikeG

Senior Member.
I see how you've misinterpreted my post. I'm talking about the lack of damage to the exterior caused by the supposedly-falling interior, not damage that happened 7 hours before collapse. The idea that free fall buckling is possible, the claim of this thread, depends on the exterior being like the wall of a soda can. That means that it has to be a thin tube, the only structure remaining after the building gets hollowed out. We can see that this view is false, because it is not possible for the middle of the building to hollow itself out, leaving just a few broken windows on the exterior. The NIST account wants us to believe that after column 79 failed, a sequence of floor failures traveled right to the top of the building, and then column failures propagated west, as falling girders took out beams and girders next to them on the way down, causing neighboring columns to become unsupported, then buckle. If falling floors are capable of propagating damage west, they would also take out bits and pieces of the external frame to the north, east and south. Even the broken windows that we can see do not have falling concrete, beams, furniture or the like flying out of them. That shows that buckling of the exterior moment frame only is not what we saw in that 2 seconds of free fall.
I see your point.

I still think that a good deal of the ongoing debate about internal damage does not pay enough attention to external impacts on WTC 7 that resulted from the collapse of WTC 1 and WTC 2.

gal-wtc-nypd-12-jpg.jpg

And what it did to WTC 7

WTC7Corner.jpg

My two cents.
 

Jedo

Member
I see your point.

I still think that a good deal of the ongoing debate about internal damage does not pay enough attention to external impacts on WTC 7 that resulted from the collapse of WTC 1 and WTC 2.

View attachment 31789

And what it did to WTC 7

View attachment 31790

My two cents.
Also here: what has this to do with the question in the OP (buckling -> free fall)? The external damage did play a role where the buckling occurred, however, there was also buckling in the NIST simulation without damage from debris impact. While the damage from debris impact did play a role as to where the buckling occurs, it is not a necessary condition for buckling to happen.
 

John85

Member
Well I guess @Mick West just wanted to demonstrate the effect how much weight a soda can support before buckling. Btw the ratio of the walls of a soda can to its diameter is approximately 50 times smaller than the ratio of largest transversal dimension of the outer columns compared to the width of WTC7. The phenomena of buckling still applies, though. Actually it is a major concern in structural engineering of high-rise buildings, see any textbook on that topic.

No, the maximum load a column can bear before buckling goes with the inverse square of its length. Even if the engineers constructed the columns with a safety factor of 50 for buckling, a loss of lateral support for 8 stories gives the column only 1/64 of its resistance to buckling.

How then do you explain the collapse of the East Penthouse which wasn't accompanied by any window breaking but by a travelling pressure wave?

NIST did also a study where they took out column 79 for two stories only, and also got a complete collapse of the building. So they looked at the controlled demolition theory, and showed that it is feasible to destroy the building with only having charges at a single column. However, they studied also the effects what this minimal setup for controlled demolition, like 1kg of high explosives, would be in terms of the shockwave this explosion would produce. They found that windows would certainly break due to the shockwave, and that the blast sound would be approx. 130-140dB in something like half a mile distance. Neither evidence of the impact of glass shrapnel on neighbouring buildings nor that of explosion sounds that loud have been reported.

Well, that depends on the actual stress in each element of the construction, and on the actual strength of the connections. As far as I know the connections between elements of the outer frame are made to withstand large stress in the plane of the frame, while the connections from the frame to the floor where constructed mainly for vertical load. So it is quite likely that the connections perpendicular break due to higher horizontal loads than they where constructed to bear, while the frame holds together as one piece.

Why should furniture fly out when the interior collapses? View attachment 31785
As you can see on the second image, in an internal collapse any furniture would rather tend to move inwards. Contrast this with the case of an explosion, where the shockwave would move stuff outwards. So the absence of windows breaking and furniture flying out of the building would be rather evidence against controlled demolition rather than for it.
My point is not whether the exterior frame bears the exact proportions relative to the interior as the walls of a soda can to its diameter. My point is also not whether the exterior frame was slender enough to buckle at 99% of free fall if unsupported. My point is that it is not possible for the exterior frame only to be left intact with barely a handful of broken windows while the interior collapses and detaches itself from the frame.

Conversely, if we believe that the majority of the interior had not fallen away from the exterior frame at the initiation of the 2s of free fall, we do not resolve the essential question which this thread attempts to sidestep: how did multiple core columns and supporting girders collapse in unison as if there was nothing beneath them without some kind of simultaneous explosive or incendiary charges?
 

Jeffrey Orling

Senior Member
I do not quite understand what the part below the +++ has to do with the buckling / free fall question mentioned in the OP?
A columns's strength is determined by several factors... its cross sectional area, one of the being its slenderness ratio in the shorted plan axis.... another being how the column is fixed at each end and so on. All the columns above the foundation has end to end splices which offered little lateral resistance and so could be classified as free, not pinned or fixed.

If you were to remove the bracing from a multi-part column, the location where it would "buckle" or fail would be the column to column connections... essentially the failure would look like collapsing jenga blocks. You don't doubt this do you? And there is plenty of evidence of this type of failures of these columns... look in the debris pile. Barely a crippled web or flange... but many almost intact 3 story tall columns perfectly straight.
 

benthamitemetric

Senior Member
My point is that it is not possible for the exterior frame only to be left intact with barely a handful of broken windows while the interior collapses and detaches itself from the frame.
Can you make this into a more specific hypothesis and show your reasoning? How many windows on the north face would necessarily break in natural progressive collapse scenario and how did you arrive at that number? I note that the only full global failure simulation output of the progressive failure mode we do have, NIST's, seems to show relatively few major distortions on the North face of the building during the initial stages of the collapse event.
 

John85

Member
Can you make this into a more specific hypothesis and show your reasoning? How many windows on the north face would necessarily break in natural progressive collapse scenario and how did you arrive at that number? I note that the only full global failure simulation output of the progressive failure mode we do have, NIST's, seems to show relatively few major distortions on the North face of the building during the initial stages of the collapse event.
Do you ask because you believe that the majority of the interior did collapse while the exterior frame remained standing?
 

Jedo

Member
My point is that it is not possible for the exterior frame only to be left intact with barely a handful of broken windows while the interior collapses and detaches itself from the frame.
How can you claim this is impossible without looking at the exact model? Shouldn't the possibility of this depend on the stress in each of the elements of the building, particularly so in the connection elements? Wouldn't you agree that, after looking at the various connections, that the column-column splices and the column-spandrel moment connections probably can take much higher stress and shear loads before failure than the column-girder connections, which were just seated connections? And wouldn't you agree that is then plausible that all girder-column connections fail before the moment frame of the facade?

Conversely, if we believe that the majority of the interior had not fallen away from the exterior frame at the initiation of the 2s of free fall, we do not resolve the essential question which this thread attempts to sidestep: how did multiple core columns and supporting girders collapse in unison as if there was nothing beneath them without some kind of simultaneous explosive or incendiary charges?
Sorry, but I can't follow you here. What has your assertion to do with the last sentence? I tried to believe your assertion for the sake of the argument for a second, but I can't see how it plays into your question.

Please note that the question of internal collapse prior to external collapse has nothing to do with the question of controlled demolition vs fire. The celebrated Danny Jowenko, "top European demolition expert" (according to AE911), just said in that famous video that a controlled demolition would also only take out the core columns, since the exterior would collapse then automatically.
 

benthamitemetric

Senior Member
Do you ask because you believe that the majority of the interior did collapse while the exterior frame remained standing?
I ask because you made a rather unclear claim without providing the bases from which it followed. I do think it is plausible that the exterior frame would remain standing while the interior collapsed, however. As I said, the NIST progressive collapse model shows that to be a reasonable possibility.

So can you please be a bit more specific as to what you are claiming and why?
 

John85

Member
I ask because you made a rather unclear claim without providing the bases from which it followed. I do think it is plausible that the exterior frame would remain standing while the interior collapsed, however. As I said, the NIST progressive collapse model shows that to be a reasonable possibility.

So can you please be a bit more specific as to what you are claiming and why?
Either you believe that the majority of the interior detached itself from the exterior frame, or you don't. I don't mind if you keep that private to yourself. NIST did not believe that building 7 hollowed itself out like a soda can. You can see in the OP that once about a third or 40% of the eastern interior has fallen, the entire rest of the building begins to descend as one. How many core columns is that that fail in the same instant? Looks like 18 to me:

WTC_7_Plan.jpg


Look at the NIST simulation again if you don't believe me. Now how do you suppose those columns in blue failed at the same moment?
 

John85

Member
How can you claim this is impossible without looking at the exact model? Shouldn't the possibility of this depend on the stress in each of the elements of the building, particularly so in the connection elements? Wouldn't you agree that, after looking at the various connections, that the column-column splices and the column-spandrel moment connections probably can take much higher stress and shear loads before failure than the column-girder connections, which were just seated connections? And wouldn't you agree that is then plausible that all girder-column connections fail before the moment frame of the facade?


Sorry, but I can't follow you here. What has your assertion to do with the last sentence? I tried to believe your assertion for the sake of the argument for a second, but I can't see how it plays into your question.

Please note that the question of internal collapse prior to external collapse has nothing to do with the question of controlled demolition vs fire. The celebrated Danny Jowenko, "top European demolition expert" (according to AE911), just said in that famous video that a controlled demolition would also only take out the core columns, since the exterior would collapse then automatically.
Look at the NIST model and it predicts bits flying out the windows. Look at the left-hand side as the collapse progresses.

As to the second point, it appears to me that this thread seeks to explain free fall descent by saying that what we saw dropping at free fall acceleration for over 2s was only the unsupported exterior moment frame, which buckled like the walls of a soda can, and not the whole building all together. Looking at the NIST model, however, shows that only around 40% or so of the interior is claimed to have fallen before the onset of global collapse. As such, 60% or so of what collapses at free fall is not claimed to be unsupported external facade but actually includes as many as 18 core columns and their supporting girders, all dropping together.
 

benthamitemetric

Senior Member
Either you believe that the majority of the interior detached itself from the exterior frame, or you don't. I don't mind if you keep that private to yourself. NIST did not believe that building 7 hollowed itself out like a soda can. You can see in the OP that once about a third or 40% of the eastern interior has fallen, the entire rest of the building begins to descend as one. How many core columns is that that fail in the same instant? Looks like 18 to me:

View attachment 31791


Look at the NIST simulation again if you don't believe me. Now how do you suppose those columns in blue failed at the same moment?
I think a substantial portion of the interior collapsed in the initial phase, as shown in NIST's model and as inferred from the collapses of the penthouses. I've never tried to look at the NIST output frame by frame to quantify exactly how many columns had failed therein prior to the so called free fall period. Have you? How many remaining interior columns would be too many for the observed movement of the north face to have taken place as a result of buckling and how did you reach that conclusion?
 

John85

Member
I think a substantial portion of the interior collapsed in the initial phase, as shown in NIST's model and as inferred from the collapses of the penthouses. I've never tried to look at the output frame by frame of the NIST output to quantify exactly how many columns had failed therein prior to the so called free fall period. Have you? How many remaining interior columns would be too many for the observed movement of the north face to have taken place as a result of buckling and how did you reach that conclusion?
The NIST video is in the OP, take a look. Is it 18 core columns that fail together, or only 15? Maybe 12? This is a big problem for natural collapse, and it will be exposed in the UAF study.
 

benthamitemetric

Senior Member
The NIST video is in the OP, take a look. Is it 18 core columns that fail together, or only 15? Maybe 12? This is a big problem for natural collapse, and it will be exposed in the UAF study.
Instead of waving your hands, throwing out guesses of the figures upon which your own argument relies, and then deferring to a study that (i) might never be published and (ii) we know nothing about at present, in any event, why don't you start by actually figuring out how many internal columns remained intact immediately prior to the so called free fall period in NIST's animation? Once you have done that, you can tell us exactly why you believe that number exceeded some heretofore undefined threshold (which threshold I assume you will actually define).
 

John85

Member
Instead of waving your hands, throwing out guesses of the figures upon which your own argument relies, and then deferring to a study that (i) might never be published and (ii) we know nothing about at present, in any event, why don't you start by actually figuring out how many internal columns remained intact immediately prior to the so called free fall period in NIST's animation? Once you have done that, you can tell us exactly why you believe that number exceeded some heretofore undefined threshold (which threshold I assume you will actually define).
How many of the building's columns must be taken away to permit the remainder to collapse at a rate indistinguishable from free fall is a calculation you need to do, given that you believe the 2 seconds of free fall was natural. Have you done any such calculation? All I need to do is show that a material amount of building was standing at the onset of global collapse that would have shown up as a descent distinguishable from free fall. NIST's own model does that for me.
 

benthamitemetric

Senior Member
How many of the building's columns must be taken away to permit the remainder to collapse at a rate indistinguishable from free fall is a calculation you need to do, given that you believe the 2 seconds of free fall was natural. Have you done any such calculation? All I need to do is show that a material amount of building was standing at the onset of global collapse that would have shown up as a descent distinguishable from free fall. NIST's own model does that for me.
What is a "material amount of building" in the context of this collapse event and how did you determine that?

We can play this game forever but it's not likely to be productive unless you put some work into your argument. You obviously reached your conclusion without having completely thought through the problem and now you are just pulling a Szamboti by substituting bare assertions and amorphous, undefined metrics for actual analysis.
 
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Jeffrey Orling

Senior Member
the FF collapse was apparently because of lateral displacement. But it appears to be the facade moment frame not the entire building. There is evidence that the interior collapse in advance of the exterior facade moment frame...


The best fit hypothesis explain what you saw was that the interior collapsed and in so doing led to the axial support of the 26 perimeter columns for the first 7 or so floors... up to the belt trusses to be pulled or pushed by the collapsing debris... out of alignment with the 57 columns above. The facade had tts support kicked out from under it and so dropped at essentially FF acceleration,
 

Jedo

Member
You can see in the OP that once about a third or 40% of the eastern interior has fallen, the entire rest of the building begins to descend as one.
How can you infer something about motion from one video frame? It is better to look at the full video, which is available at the NIST site.

I'd prefer the video from the south side, as the view to the interior is more clear. I've made a gif with one frame every two seconds, from 19.7s on one frame per second, played at double speed.

collapse_southview.gif
You can clearly see that the interior collapses before the buckling in the lower south-west corner starts (last frame). I've included a still frame where you can see the onset of buckling at 23.3s.
23-3.png

You find the video attached if you want to have a look at the frames yourself.

Does that looks like what you claimed above?

As to the second point, it appears to me that this thread seeks to explain free fall descent by saying that what we saw dropping at free fall acceleration for over 2s was only the unsupported exterior moment frame, which buckled like the walls of a soda can, and not the whole building all together. Looking at the NIST model, however, shows that only around 40% or so of the interior is claimed to have fallen before the onset of global collapse. As such, 60% or so of what collapses at free fall is not claimed to be unsupported external facade but actually includes as many as 18 core columns and their supporting girders, all dropping together.

Wehre do you find that claim in the NIST report? I found a detailed study of how the collapse progressed in NCSTAR1-9, vertically and horizontally, see e.g. p.581 (p.647 pdf) [emphasis by me]:
They go on with a study of the column loads:
They go on with a study of the exterior columns:
In the last picture you have #3 which corroborates the assertion that the exterior and interior move separatley:
So your claim that NIST's results show that about 60% of the interior core is intact before the exterior frame collapses seems unsubstantiated.


Look at the NIST model and it predicts bits flying out the windows. Look at the left-hand side as the collapse progresses.
Can you please show me where you believe to see windows flying out? As far as I am aware of it, NIST didn't specify the modelling of windows in their global simulation. In fact, the term "window" doesn't appear in the therefore relevant Chapter 12 of NCSTAR1-9 at all, neither in the total NCSTAR 1-9A. So I assumed they didn't include windows in their global collapse model. But if maybe you can correct me by presenting evidence of the explicit modelling of windows?


Personal note for @John85 : It really would be helpful if you would substantiate your claims with evidence instead of letting the other party do the work of checking your claims. Phrases like "look at the NIST simulation again if you don't believe me" etc are not specific enough. The NIST reports regarding WTC7 together have around 1000 pages, they provided over a dozen videos, so it would be really really helpful if you include specific references in the future, including page numbers or video time stamps.

Furthermore, would you just accept, please. for the sake of argument, the premises of the thread?

Even if the columns buckled, wouldn't they still provide some resistance? Well yes, but the key question here is how much resistance.
The question here is (paraphrased) "What would happen IF the columns buckle?" So please do not start to argue in this thread if they actually do buckle. Please accept the premises and discuss the plausibility of any conclusions drawn upon them.
 

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John85

Member
What is a "material amount of building" in the context of this collapse event and how did you determine that?

We can play this game forever but it's not likely to be productive unless you put some work into your argument. You obviously reached your conclusion without having completely thought through the problem and now you are just pulling a Szamboti by substituting bare assertions and amorphous, undefined metrics for actual analysis.
It's obvious that those proposing a natural free fall collapse need to account for this acceleration in spite of the putative initial east penthouse collapse only removing a minority of columns within the building.
 

benthamitemetric

Senior Member
It's obvious that those proposing a natural free fall collapse need to account for this acceleration in spite of the putative initial east penthouse collapse only removing a minority of columns within the building.
I was trying to get you to put in the time to actually work through the NIST report at a high level of detail and therefrom actually make a detailed, fact-based argument. You instead chose to simply repeat the same thing over and over with different words. Meanwhile, Jedo did the work that you should have and, unsurprisingly, he discovered what I expected you would ultimately discover—that your initial characterization of what was happening in the NIST model, the very basis for your claim, was entirely incorrect.

Can you see the difference between how you researched and stated your claim and how Jedo researched and rebutted it? You should try to be more like Jedo, not because of what he concluded, but because of the process he went through (actually making sure he fully understood the facts) to get to that conclusion.
 

benthamitemetric

Senior Member
I see you would rather narrate my posts than respond to them. At least you have the basis of a catchy meme, 'be more like Jedo'. That said, Jedo has not rebutted my points.
You have yet to make a single, fact-based point. For example, you still have failed to identify how many interior columns remained in tact immediately prior to the beginning of the so-called free fall period per NIST's analysis. Was it 18 interior columns as you seemed to imply above? (Hint: No.) Once you've established the facts re the state of the columns in NIST's model at a given time, then you can make a fact-based argument about what could or couldn't have happened at that time given that state. As Jedo has shown, there is a high level of detail about the state of the interior columns over time that is provided to you in the NIST report. Please use it (and by that I mean please actually read the NIST report, not just Jedo's post, yourself and draw facts from it) to make an actual fact-based argument.

Since this argument is going in circles and my point has been made, please feel free to have the last word if you choose to go another time 'round the loop instead of simply making an actual argument.
 

John85

Member
How can you infer something about motion from one video frame? It is better to look at the full video, which is available at the NIST site.

I'd prefer the video from the south side, as the view to the interior is more clear. I've made a gif with one frame every two seconds, from 19.7s on one frame per second, played at double speed.

View attachment 31806
You can clearly see that the interior collapses before the buckling in the lower south-west corner starts (last frame). I've included a still frame where you can see the onset of buckling at 23.3s.
View attachment 31807

You find the video attached if you want to have a look at the frames yourself.

Does that looks like what you claimed above?




Wehre do you find that claim in the NIST report? I found a detailed study of how the collapse progressed in NCSTAR1-9, vertically and horizontally, see e.g. p.581 (p.647 pdf) [emphasis by me]:
They go on with a study of the column loads:
They go on with a study of the exterior columns:
In the last picture you have #3 which corroborates the assertion that the exterior and interior move separatley:
So your claim that NIST's results show that about 60% of the interior core is intact before the exterior frame collapses seems unsubstantiated.




Can you please show me where you believe to see windows flying out? As far as I am aware of it, NIST didn't specify the modelling of windows in their global simulation. In fact, the term "window" doesn't appear in the therefore relevant Chapter 12 of NCSTAR1-9 at all, neither in the total NCSTAR 1-9A. So I assumed they didn't include windows in their global collapse model. But if maybe you can correct me by presenting evidence of the explicit modelling of windows?


Personal note for @John85 : It really would be helpful if you would substantiate your claims with evidence instead of letting the other party do the work of checking your claims. Phrases like "look at the NIST simulation again if you don't believe me" etc are not specific enough. The NIST reports regarding WTC7 together have around 1000 pages, they provided over a dozen videos, so it would be really really helpful if you include specific references in the future, including page numbers or video time stamps.

Furthermore, would you just accept, please. for the sake of argument, the premises of the thread?



The question here is (paraphrased) "What would happen IF the columns buckle?" So please do not start to argue in this thread if they actually do buckle. Please accept the premises and discuss the plausibility of any conclusions drawn upon them.
Your own post contains within it the evidence for my point, and I have assumed common knowledge of what the NIST simulation is and where to find it. The gif and still image above show that bits and pieces were predicted to fly out the building during the initial column 79 collapse, before global collapse. In this view, those are visible on the right hand side. But where is the falling debris in real life?

Also, the freeze frame image does show that the vertical section of building that collapsed with column 79 was only about 40% of the width of the building, as I claimed above.

As such, when global collapse initiated, the remaining 60% (roughly) fell as one. You capture the moment in the freeze frame. However challenging it is to accept, 60% (roughly) of a structure will provide more than an imperceptible amount of resistance and therefore not collapse at free fall acceleration naturally. The OP seems to take the view that free fall collapse is explained by the notion that it is just the external frame which buckles at free fall speed, in isolation from the rest of the building. We can clearly see even from NIST's material that this idea is false.
 

Mick West

Administrator
Staff member
As such, when global collapse initiated, the remaining 60% (roughly) fell as one. You capture the moment in the freeze frame. However challenging it is to accept, 60% (roughly) of a structure will provide more than an imperceptible amount of resistance and therefore not collapse at free fall acceleration naturally. The OP seems to take the view that free fall collapse is explained by the notion that it is just the external frame which buckles at free fall speed, in isolation from the rest of the building. We can clearly see even from NIST's material that this idea is false.
Indeed, because the remain core columns obviously would have to also buckled.

Which they did, you just don't see them. Luckily NIST did a visualization of the core columns buckling (attached)
Source: https://www.youtube.com/watch?v=BvWbb5EBKTQ


It's not at the same angle as the other visualization, so you can't do a perfect overlay. But roughly here you can see at time 22.1 the interior columns have all buckled, hence the interior on the right hand side (West) is falling with the building.

Metabunk 2018-02-13 16-02-02.jpg


This can also be seen in the south view, where the floors on the West side (to the left here) are seen to be falling as the interior columns buckle before the exterior buckling. You can see this by the blue colored floor slabs.

Metabunk 2018-02-13 16-05-24.jpg


Perhaps I should add this to the OP, if people agree this is what the simulation is showing.

Of interest here is the somewhat isolated buckling of the far west columns, which buckle about 0.5 seconds before the more central columns. This is probably related to the impact damage and the way it changed the load redistribution.
 

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Mick West

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Also, the freeze frame image does show that the vertical section of building that collapsed with column 79 was only about 40% of the width of the building, as I claimed above.

As such, when global collapse initiated, the remaining 60% (roughly) fell as one. You capture the moment in the freeze frame. However challenging it is to accept, 60% (roughly) of a structure will provide more than an imperceptible amount of resistance and therefore not collapse at free fall acceleration naturally. The OP seems to take the view that free fall collapse is explained by the notion that it is just the external frame which buckles at free fall speed, in isolation from the rest of the building. We can clearly see even from NIST's material that this idea is false.
And to clarify my "indeed" from above, I'm agreeing it's false that "it is just the external frame which buckles at free fall speed, in isolation from the rest of the building". However as shown by the interior column visualization, and the south view full height visualization (already explained by @Jedo) the entire interior of the building had either full collapsed or was on buckled columns when the exterior buckled. Hence there was nothing (other than buckled columns) holding up the building during the famous 2.5 seconds.
 

Mick West

Administrator
Staff member
5. NIST's complete collapse simulation/animation appears strange in that many columns are shown as still connected despite bowing very far from vertical alignment - they almost look like noodles. Is this realistic? I don't think anyone has tried to replicate this by a simulation of their own, and only remember non-expert judgements on this issue, so don't believe it just because I say I think there may be a problem. Are NIST's sim-columns too ductile?
I know you asked this over a year ago, but yes, I think they are too ductile. However I doubt it's a problem except in visualization of where they end up, and how they get there. They would probably have broken into pieces sooner - but either way the resistance they offer is close to 0% of their full strength.
 

Jedo

Member
Of interest here is the somewhat isolated buckling of the far west columns, which buckle about 0.5 seconds before the more central columns. This is probably related to the impact damage and the way it changed the load redistribution.
NCSTAR1-9 p. 586 (p. 652 pdf) confirms that:
 
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Mick West

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NCSTAR1-9 p. 586 (p. 652 pdf)
Yeah, but I meant the core columns. The west core columns buckled before the center core columns, even though the east core columns (79,80,81) were the first to buckle.
 

John85

Member
Perhaps I should add this to the OP, if people agree this is what the simulation is showing.
And yet your OP does quote from NIST's WTC 7 FAQs, I wouldn't say that it was a misinterpretation of it. I've been caught out by this before - we would expect that their FAQ webpage would be an accurate distillation of the in depth findings for the public to read about, but in this case, what they say in the FAQs does not agree with the model or collapse theory.

The FAQ was this:

And I would suggest that their intention by including this FAQ is not merely to inform the public of their work; it is to give a rebuttal to a specific challenge many have been making in the truth movement. Although the FAQ is a little blunt, it is a serious question how free fall acceleration could occur in a non-demolition collapse, especially since AE911 requested a correction to NIST's original claim that there was no free fall acceleration.

The answer refers to the falling facade:

https://www.nist.gov/el/faqs-nist-wtc-7-investigation

NIST therefore explains why the exterior frame collapsed so suddenly, indeed at free fall acceleration, but does not go into detail about the internal rapid failures necessary for this. The answer to the most threatening question, on which they had already been caught out by claiming there had been no free fall, refers to the intuitive aspect of their contention (Oh it was just the facade that fell fast), while avoiding describing the internal failures which happened just as fast.

It's the rapid and total failure of the remaining core columns that I doubt. I doubt that their buckling would have progressed as quickly west as they claim, and doubt that the failures in their model would have led to a whole-building descent indistinguishable from free fall.
 

Jedo

Member
Yeah, but I meant the core columns. The west core columns buckled before the center core columns, even though the east core columns (79,80,81) were the first to buckle.
But this is also covered in the NIST report, as I cited in the second block (with Figs. 12-57 to 12-59) in the above post: Column group 7 (mid-west) is failing at 4.3s before groups 3 to 5 (middle) and 6 and 8 (north- and south-west).
 

Jeffrey Orling

Senior Member
Yeah, but I meant the core columns. The west core columns buckled before the center core columns, even though the east core columns (79,80,81) were the first to buckle.
Are you defining any column not part of the perimeter as a core column?

The core is basically an area inside the building where vertical conveyances are located, mechanical risers and often bathrooms... outside the core are the intended USE spaces... apartments or office space or storage space.

The region around columns 79-80 and 81 was not in the core.

The core does NOT mean the center... though the core often IS in the center for multiple reasons.
 

Mick West

Administrator
Staff member
NIST therefore explains why the exterior frame collapsed so suddenly, indeed at free fall acceleration, but does not go into detail about the internal rapid failures necessary for this. The answer to the most threatening question, on which they had already been caught out by claiming there had been no free fall, refers to the intuitive aspect of their contention (Oh it was just the facade that fell fast), while avoiding describing the internal failures which happened just as fast.
The facade was the last thing to buckle, so ultimately it was that buckling that caused the visible collapse. There's plenty more detail in the full report for those who seek it out.

It's the rapid and total failure of the remaining core columns that I doubt. I doubt that their buckling would have progressed as quickly west as they claim, and doubt that the failures in their model would have led to a whole-building descent indistinguishable from free fall.
Your doubt is irrelevant here. The simulation shows the remaining interior columns bucking. If you have some math that shows why this would not happen then let's see it. But "seems weird to me" is the fundamental failed argument of the 9/11 Truth movement.
 

Mick West

Administrator
Staff member
But this is also covered in the NIST report, as I cited in the second block (with Figs. 12-57 to 12-59) in the above post: Column group 7 (mid-west) is failing at 4.3s before groups 3 to 5 (middle) and 6 and 8 (north- and south-west).
Ah yes, sorry I did not read that in full.
 

John85

Member
But "seems weird to me" is the fundamental failed argument of the 9/11 Truth movement.
I didn't say weird though, did I? It is highly unlikely and anomalous that 60% of a building would collapse naturally at free fall acceleration, not weird. That recognition provokes skepticism, because great claims require great evidence, and NIST doesn't provide great evidence. Where has your skepticism gone?
 

Mick West

Administrator
Staff member
I didn't say weird though, did I? It is highly unlikely and anomalous that 60% of a building would collapse naturally at free fall acceleration, not weird. That recognition provokes skepticism, because great claims require great evidence, and NIST doesn't provide great evidence. Where has your skepticism gone?
"Weird" or "highly unlikely and anomalous" seem like similar assessments to me.

NIST gives an explanation, and it involves buckling of columns over a few seconds preceding the exterior collapse. They back it up with simulations which you reject because you can't repeat them.

I'd like to see the simulations repeated, but I find no significant reason to doubt the broad strokes of what they show. Even @Tony Szamboti goes most of the way towards agreeing with the global collapse model, differing only in how the interior columns failed.

Why don't you wait for the Hulsey study, it should be out any day now.

[Edit:] actually now the site says "May or June". But the point remains - SHOW that NIST is wrong, don't just say it seems "highly unlikely and anomalous" to you.
 
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John85

Member
I'd like to see the simulations repeated, but I find no significant reason to doubt the broad strokes of what they show
Have you considered any other evidence that casts doubt on what NIST claims? What makes you confident that they are right?
 

Mick West

Administrator
Staff member
Have you considered any other evidence that casts doubt on what NIST claims? What makes you confident that they are right?
Of course I've considered other evidence. The entire point of this site is to consider other evidence. Have you not seen me write tens of thousands of words about claimed evidence that casts doubt on NIST's claims? Have you not looked at the 283 other threads in the 9/11 forum, 67 of which were started by me?

I'm not 100% confident that NIST are 100% right, but their general explanation makes a lot of sense, and seems to fit the observed facts.

This is getting off topic though. The topic is the role of bucking in the collapse. NIST describes when this buckling might have occurred, based on the observations of the fire, the impact damage, and the actual collapse. In my OP I did some simple experiments to demonstrate how much a structure can weaken when unbraced and/or buckled. I explained where in the structure the buckling occurred.

I understand you think this is "highly unlikely and anomalous", but you've not presented any good evidence for this. So again I suggest you wait for the Hulsey study, which presumably will be attempting to make the argument you are making, but with an actual model.
 
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