How Buckling Led to "Free Fall" acceleration for part of WTC7's Collapse.

And that's what happened with WTC7 during those 2.25 seconds of "free fall". The columns below had buckled, and offered negligible resistance. Still tons of resistance, but compared to the mass they previously supported, it was practically nothing. Hence 99% freefall.

I'm curious what evidence is there of the columns buckling? In every video I've seen of WTC7 the buckling is hidden behind other buildings, the video that Cube Radio posted isn't entirely clear (within the same standard of evidence that applies to no jolt claims). Is your position that buckling as described by NIST is possible, or it is that it actually happen?
 
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I'm curious what evidence is there of the columns buckling?
This may sound like a quip, but I think it is the best there is: The fact that the top of the building came pretty straight down is very convincing that the columns buckled. Seeing that the building had burned for hours, had been observed to be unstable and deforming, and the sequence of collapse events (there was early movement; then east penthouse, then west penthouse, immeditaly followed by north facade; all the rest, too) are best explained by columns buckling in sequence: 79-81 quickly; short pause; then remaining core columns quickly from east to west; then perimeter from the inside out in rapid succession -> loads are distributed at the sound of speed in the medium, i.e. steel. This scenario requires no assumption that isn't already known to have been true: We know, from several engineering studies, that floors around columns 79 or 80 could possibly have failed on several floors from several failure modes, given the fires that were actually observed. All studies agree that such failers could possibly trigger a collapse progression that leds to the buckling of column 79 or 80; and that this could then progress to total collapse.

The only alternative is rapid - this means: explosive - demolition by deliberately planted devices. This would require several assumptions that are not in evidence, and where there actually exists evidence against. Most notably the absence of audible explosions loud enough to be able to sever those columns. The existence of uncontrolled fires on many floors is also a strong indication that controlled demolition would have been exceedingly improbable: Heat easily destroys explosive charges, detonators and the cables or RC equipment needed to trigger them.

In every video I've seen of WTC7 the buckling is hidden behind other buildings, the video that Cube Radio posted isn't entirely clear (within the same standard of evidence that applies to no jolt claims). Is your position that buckling as described by NIST is possible, or it is that it actually happen?
If you weigh the alternatives (I see two; do you see any third?), assign probabilities to things not known to have existed, and apply Occam's razor prudently, you will agree that the "buckled in the course of progressive collapse" scenriao is vastly more probable than "controlled demolition", given the confluence of ALL evidence.
 
... columns around the whole perimeter losing lateral bracing for 8 stories to facilitate free fall for 2.25 seconds is a fairly unlikely event, that requires at least 8 lateral braces per column for however many columns there were to fail within a fraction of time to correspond to the observed motion. ...
I don't think any of that is true.
The north perimeter columns needed to buckle and be severed only once, 8 floors above ground. Once the upper part falls past the lower part (8 storeys of still standing wall), the upper part meets no, or negligible, resistance until it hits the ground.

Edited to add: Are you aware of the transfer trusses on the north side? Many of the north perimeter columns didn't go all the way to the ground - they rested on cantilevers - strong, horizontal beams - that transfered the load above the 8th floor to columns that were offset a bit to the inside. Once those lower columns buckle anywhere below the 8th floor, the wall above 8th floor comes down without resistance for 8 storeys.
 
I'm curious what evidence is there of the columns buckling? In every video I've seen of WTC7 the buckling is hidden behind other buildings, the video that Cube Radio posted isn't entirely clear (within the same standard of evidence that applies to no jolt claims). Is your position that buckling as described by NIST is possible, or it is that it actually happen?

Certainly possible, and quite probable. After-the-fact evidence would be in the form of bent columns - however they would only bend so far before they came apart at the joins. Of course most of the lower columns would be buried under the upper level debris.
 
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Certainly possible, and quite probable. After-the-fact evidence would be in the form of bent columns - however they would only bend so far before they came apart at the joins. Of course most of the lower columns would be buried under the upper level debris.
Thank you for the reply, this however doesn't exactly answer my question. As far as I understand NIST actually did not have access to the structural steel since their research into WTC7 was not conducted until years later. The reason I'm curious if there is actual evidence pointing to that fact is that columns around the whole perimeter losing lateral bracing for 8 stories to facilitate free fall for 2.25 seconds is a fairly unlikely event, that requires at least 8 lateral braces per column for however many columns there were to fail within a fraction of time to correspond to the observed motion. What indicators do you think we're there for NIST to make that claim?
 
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Thank you for reply, respectfully, allow me to disagree with a number of your points:
This may sound like a quip, but I think it is the best there is: The fact that the top of the building came pretty straight down is very convincing that the columns buckled.
This cannot be used as evidence to support the fact that columns buckled, at best that is a conclusion one can reach after the process of elimination, leaving columns buckling in the realm of possibility, not in the realm of facts. While I agree with the argument that roof falling straight down is indicative of columns failing, it could mean CD as well as a significant failure of the foundation, leaving at least 3 different scenarios that can explain the motion of the roof.

This scenario requires no assumption that isn't already known to have been true: We know, from several engineering studies, that floors around columns 79 or 80 could possibly have failed on several floors from several failure modes, given the fires that were actually observed. All studies agree that such failers could possibly trigger a collapse progression that leds to the buckling of column 79 or 80; and that this could then progress to total collapse.
This scenario requires a leap of logic since there is no casual connection between one column buckling and a complete symmetrical collapse for the following reasons:
1. A column in the east side of the building carries only the weight of the building immediately above itself according to its tributary area; that is to say that the western columns do not share the weight with the eastern side - those are two separate masses connected by horizontal members.
2. The column to beam connections are explicitly designed to fail such that the column is unaffected: if the beam experiences the overload, the connections are designed to fail in such a manner than would not allow the lateral propagation of the collapse.
3. The western penthouse drops just a moment before the whole building while the eastern penthouse drops a few seconds prior. This indicates that should the lateral failure propagation happen we would expect to see the eastern side dropping few seconds before the western side, not simultaneously, since the failure propagation is expected to travel at the same speed in both directions.

The only alternative is rapid - this means: explosive - demolition by deliberately planted devices. This would require several assumptions that are not in evidence, and where there actually exists evidence against. Most notably the absence of audible explosions loud enough to be able to sever those columns. The existence of uncontrolled fires on many floors is also a strong indication that controlled demolition would have been exceedingly improbable: Heat easily destroys explosive charges, detonators and the cables or RC equipment needed to trigger them.
Absence of evidence is not an evidence of absence. That would not stand to any reasonable scrutiny, furthermore it would work against your argument as well: if absence of audible explosions is evidence of those explosions not being there at all, then lack of visible evidence of columns buckling would also serve as an argument against the columns buckling. As far as fires goes one can easily envision fireproofed containers or placing the devices within the fireproofed internals of the building. Neither can be used to state with any degree of certainty that there were no explosives, at best it's a circumstantial evidence to make CD hypothesis less likely; such notion is easily countered by the eyewitnesses' reports of explosions - it would also count as only a circumstantial evidence, not enough to prove the explosions did occur, but enough to state that they might have occurred.


I don't think any of that is true.
The north perimeter columns needed to buckle and be severed only once, 8 floors above ground. Once the upper part falls past the lower part (8 storeys of still standing wall), the upper part meets no, or negligible, resistance until it hits the ground.
The columns would only buckle along their unbraced height, otherwise they would provide a significant resistance, therefore making it necessary for the columns to be unbraced for the height of 8 stories to facilitate that period of free fall acceleration due to buckling. Otherwise the building would've been in free fall for a much shorter period of time - only as much as the height of the unbraced buckled column would allow. It is also necessary for the columns to fail within a fraction of the second of each other to explain the motion of the roof that is observed.

Edited to add: Are you aware of the transfer trusses on the north side? Many of the north perimeter columns didn't go all the way to the ground - they rested on cantilevers - strong, horizontal beams - that transfered the load above the 8th floor to columns that were offset a bit to the inside. Once those lower columns buckle anywhere below the 8th floor, the wall above 8th floor comes down without resistance for 8 storeys.
I am, but would you not agree that a failure of the northern side of the building would drop that side first?

If you weigh the alternatives (I see two; do you see any third?), assign probabilities to things not known to have existed, and apply Occam's razor prudently, you will agree that the "buckled in the course of progressive collapse" scenriao is vastly more probable than "controlled demolition", given the confluence of ALL evidence.
Occam's Razor is not an arbiter of truth, it's tendency of simpler explanations being the correct one. In either case, according to Dr. Sunder of NIST, WTC7 failure was a unique event, first of it's kind; furthermore it is still true that historically no steel frame building experienced a complete collapse due to fires. Those considerations would point Occam's Razor towards the CD hypothesis almost automatically, if we look solely at the WTC7 without going through the whole 9/11. [off topic gish gallop removed by Deirdre]

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1. A column in the east side of the building carries only the weight of the building immediately above itself according to its tributary area; that is to say that the western columns do not share the weight with the eastern side - those are two separate masses connected by horizontal members.
2. The column to beam connections are explicitly designed to fail such that the column is unaffected: if the beam experiences the overload, the connections are designed to fail in such a manner than would not allow the lateral propagation of the collapse.
This doesn't sound right at all. you make it sound like I can remove the entire east side and the building will remain standing. and that the columns wont be affected at all by an overloaded beam.

Do you have construction documentation to back this up?
 
While I agree with the argument that roof falling straight down is indicative of columns failing, it could mean CD as well as a significant failure of the foundation, leaving at least 3 different scenarios that can explain the motion of the roof.
which is what Oystein already said.
 
Absence of evidence is not an evidence of absence. That would not stand to any reasonable scrutiny, furthermore it would work against your argument as well: if absence of audible explosions is evidence of those explosions not being there at all, then lack of visible evidence of columns buckling would also serve as an argument against the columns buckling.
no. because columns are hidden behind buildings and walls. Audio isn't hidden.
 
which is what Oystein already said.
To be entirely precise he said 2, but I see your point completely.

This doesn't sound right at all. you make it sound like I can remove the entire east side and the building will remain standing. and that the columns wont be affected at all by an overloaded beam.

Do you have construction documentation to back this up?

How technical would you want it to be? I was taught that in the first year of engineering and it was used afterwards in all the design classes. I am not sure if any of the Engineering Handbooks would have that basic of information, my book is all the way in a different city, so I can't really check.

I can provide a concordia university lecture pdf here: http://users.encs.concordia.ca/home/x/xiaom_h/Study/Load Path and Tributary Areas.pdf

and

Texas A&M University, faculty of architecture pdf: http://faculty.arch.tamu.edu/media/cms_page_media/4559/NS12-1loadsEx.pdf

Honestly, this question puts me in a peculiar position: it's almost equivalent to asking me to find documentation to air being transparent.

no. because columns are hidden behind buildings and walls. Audio isn't hidden.

Audio can be easily retarded by the same walls that are hiding the columns, as well as the outer wall of the building. Sound can be more or less intense depending on the type of the demolition device, it's energy yield, and the number of charges used (as you don't need one loud blast, you could use a number of smaller ones).
 
hmm looked at this slideshow and I'm not seeing how that supports your statement. it seems to support mine. :)
which statement did you have that the pdf supports? the column, as clearly explained, only carries the weight above itself, it does not carry the weight beyond its tributary area, hence that weight is not affecting that column. it could be said that given solid moment connections the lack of one column would develop a moment in the adjacent column, but those connections are explicitly designed to prevent significant damage to the adjacent column, therefore making any following column completely unaffected, preventing lateral propagation.

This video shows a typical behaviour one expects in the beam-to-column connection under overload. Notice the way the connection fails - it absolutely is designed to prevent lateral failure propagation*.

Source: https://www.youtube.com/watch?v=6RQXTuGPk00

*Edited for clarity

Edit: LOL, I just noticed that it's a NIST video I linked.
 
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This video shows a typical behaviour one expects in the beam-to-column connection under overload. Notice the way the connection fails - it absolutely is designed to prevent lateral failure propagation*.
You can download the pdf from this page https://www.nist.gov/publications/e...onnections-under-column-removal?pub_id=906046
From page 37
3.4 LOADING APARATUS AND TEST SEQUENCE
A hydraulic ram with a capacity of 600 kip (2669 kN) and a 20 in (508 mm) stroke was used to apply a vertical downward load to the center column of the test specimens. The load was applied under displacement control at a rate of 1 in/min (25 mm/min).

Pre-test predictions of both the WUF-B and RBS specimens indicated that the stroke capacity of the hydraulic ram was not adequate to accommodate the maximum expected vertical displacement of the center column at failure. To adjust the stroke of the hydraulic ram, the specimen was unloaded when the ram had extended about 18 in (457 mm). Steel blocks were inserted between the hydraulic ram and the top of the center column, and the specimen was reloaded.
It could only propagate 25 mm/min in that YT-video.
 
but those connections are explicitly designed to prevent significant damage to the adjacent column, therefore making any following column completely unaffected, preventing lateral propagation.
then why is NIST testing, in 2011, designs to improve standards to prevent widespread collapse, if buildings built when the WTC7 was built already don't experience widespread collapse? seems like a silly waste of time.
upload_2017-6-17_3-54-11.png
 
The descent of the facade as seen is explained by the fact that there was a marked change in the structure at the facade all around the building at floor 8...top of floor 7. Just look at the number of columns above this and below in the facade. Above there were 57 columns... below there were 36. floors 5-7 were trusses and the vertical forces were resolved into slanted columns.

The upper 40 floors of the facade translated and rotated ... and there were no longer columns below it to resist the descent,

@madcanada.. you need to know what the structure was... and you clearly don't.
 

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Thank you for reply, respectfully, allow me to disagree with a number of your points:

This cannot be used as evidence to support the fact that columns buckled, at best that is a conclusion one can reach after the process of elimination, leaving columns buckling in the realm of possibility, not in the realm of facts. While I agree with the argument that roof falling straight down is indicative of columns failing, it could mean CD as well
You are so far not disagreeing with me, but agreeing completely.

[as well] as a significant failure of the foundation, leaving at least 3 different scenarios that can explain the motion of the roof.
Can you get a bit of detail in here and describe the process you envision? I fail to see how a failure of the foundation would lead to column failure 8 floors above ground, or how such foundation failure would be triggered by the ciscumstances and events that are in evidence.

This scenario requires a leap of logic since there is no casual connection between one column buckling and a complete symmetrical collapse ...
The phrase "complete symmetrical collapse" is bullshit technobabble. There is no documented, objective meaning to the term "symmetrical" as applied to building collapses. If you want to maintain the implied claim that "symmetrical collapse" is actually a thing, please do one of the following:
  1. Reference a text book or a scientific journal article that defines or discusses the "symmetry" of building collapses
  2. Describe to me a scientific method to measure objectively the "symmetry" of building collapses - what physical units is "symmetry" expressed in? What threshold values apply to differentiate "asymmetrical", "partially symmetrical" and "completely symmetrical" collapses?
Please think about this earnestly for a few minutes, give it an honest try. I think this excercise has the potential of showing you that "symmetrical collapse" is, indeed, only made-up bullshit technobabble.

Nothing about the WTC7 collapse was, in fact, "symmetrical" in any scientifically meaningful way. The following claims are thus rejected out of hand, for their premise is invalid. I'll address them individually anyway, for they contain more errors of judgement:

... for the following reasons:
1. A column in the east side of the building carries only the weight of the building immediately above itself according to its tributary area; that is to say that the western columns do not share the weight with the eastern side - those are two separate masses connected by horizontal members.
This, if true, is true only for the undamaged, as-designed building. Loads get distributed horizontally once columns start changing capacity and geometry. The part of the collapse sequence that you wish to focus on - the brief moment, a bit over 2 seconds, during which the north face drops a few feet at an average equivalent to free-fall acceleration - comes very late into the collapse sequence, when the core has already completely failed and much of the remaining load already gotten redistributed to the perimeter.

2. The column to beam connections are explicitly designed to fail such that the column is unaffected: if the beam experiences the overload, the connections are designed to fail in such a manner than would not allow the lateral propagation of the collapse.
This is nonsense. First, I do not believe that the beam connections were "designed" in any way, shape or form to manipulate their behaviour in case of a partial collapse - ALL of the building is designed to not collapse in the first place. More importantly, the floor beams (and girders) ALL play a role bracing the columns laterally. You fail a beam, and lateral bracing is effected, thus column capacity diminished.

3. The western penthouse drops just a moment before the whole building while the eastern penthouse drops a few seconds prior. This indicates that should the lateral failure propagation happen we would expect to see the eastern side dropping few seconds before the western side, not simultaneously, since the failure propagation is expected to travel at the same speed in both directions.
You make this up without taking the actual geometry and design of the structure into account. The perimeter columns are heavily bracing each other by means of moment frames. Whether you attribute the fall of the east penthouse to fire or t explosives doesn't change what happened to the eastern part of the north face: It evidently withstood the collapse of the eastern core. Your made-up fantasy cannot change that observed reality. Evidently, lateral bracing to the west core was sufficient for the north face to remain standing for a few seconds. Only when that bracing fell, too, did the north face experience capacity reduction below remaining load.

Absence of evidence is not an evidence of absence. That would not stand to any reasonable scrutiny, furthermore it would work against your argument as well: if absence of audible explosions is evidence of those explosions not being there at all, then lack of visible evidence of columns buckling would also serve as an argument against the columns buckling.
These two are not equivalent throughout.
We do have observations of the sound levels in evidence: All known videos of the WTC7 collapse had sound recording on, specifically those shot from the ground, with hand-held devices, from half a mile away or so. These sound level measurements are not evidence that are absent - this evidence is present! Somethin is absent within that evidence however: Explosion sounds.
In the case of the physical evidence on the ground: You probably cannot point me to any evidence showing the north face perimeter columns, and show me that nowhere along their length, or around the8th floor, there was no sign of buckling. THAT evidence IS indeed absent!

As for what to expect when explosive charges go off, take the Landmark Tower in Ft. Worth as an example. I have two videos here, one from quite near, one from almost half a mile away:

Source: https://www.youtube.com/watch?v=vzZBXuyIE28


Source: https://www.youtube.com/watch?v=JhaTHN3McXY&t=69

In the second video, the nearby helicopter noise makes the sound recording level go very low, and yet the explosions are clearly heard.

Another reference: Here is a firework that I filmed yesterday. I was probably 400 to 500 feet away:
https://www.youtube.com/edit?video_id=4P6J59_J7sc
Each explosive charge you hear weighs mere ounces, some perhaps less than an ounce - low explosives, not high explosives. They were MUCH louder in reality than what this recording shows: When the firework started, I was about 300 feet farther away and inside a house with no window towards the fireworks scene, and yet I heard the first "bang"s clearly.
Explosive charges - high explosives! - capable of cutting the WTC7 steel columns would have needed to be several pounds apiece - extremely much louder than fireworks!
And yet, no sound recorder captured them clearly, no witnesses described them fittingly. There were rescue workers nearby - I read one testimony of a first responder who said that they were astonished to see the tower go down in such relative silence!

So we KNOW what the sounds were near WTC7 when it collapsed - we KNOW there were no explosions consistent in timing, loudness, number and brisance with explosive demolition. It's what the evidence shows that we do have - not absent evidence.

As far as fires goes one can easily envision fireproofed containers or placing the devices within the fireproofed internals of the building.
Please do the envisioning for me!
You are aware that explosives, in order to be effective at cutting steel, must be placed directly onto the steel? If you put any insulation between the explosive and the steel, you decrease effectiveness vastly, which in turn requires that you increase charge size by an enormous factor. Not 5 pounds, say, but 50 or 100 pounds.
Please envision for me how you would go about accesing the perimeter columns ahead of time to place such bulky, insulated devices directly on them?

Yes, you "envision". I call it "fantasize".

Of course you do not have the tiniest bit of evidence for such devices nor their insulation nor the logistics of placing them. Lots of unknowns you introduce with absolutely no evidence whatsoever.

Neither can be used to state with any degree of certainty that there were no explosives, at best it's a circumstantial evidence to make CD hypothesis less likely;
This is FALSE, and the opposite is true: Yes, we can in fact state with some degree of certainty that there were no explosives. We have positive evidence of there not being the sounds of explosions at the required time with the required loudness. This greatly diminishes the probability of there having been explosive devices that actually exploded and cut columns; a probability that was low to begin with, given the fact that there exists no other evidence for explosives. So it is with the certainty of overwhelming probability that fires, not explosives, caused the collapse.

such notion is easily countered by the eyewitnesses' reports of explosions
Please cite one (1) eyewitness report of explosions consistent in timing (immediately BEFORE the collapse began), loudness (freaking awesomely LOUD!!!), number (count the columns that are cut in your fantasy) and brisance (high exposives don't rumble - they are very sharp sounds) with explosive demolition of WTC7!

Please just one. Search carefully, please! Present us with the single best, the clearest eyewitness testimony that would support explosive devices at the start of the north face collapse.

I think you may learn from this excercise that NO eyewitness testimony, consistent with explosive CD at the WTC7, actually exists.

- it would also count as only a circumstantial evidence, not enough to prove the explosions did occur, but enough to state that they might have occurred.
Again, if you search for the best such "circumstantial" bit of such evidence, you will come up empty. It doesn't exist.

The columns would only buckle along their unbraced height, otherwise they would provide a significant resistance, therefore making it necessary for the columns to be unbraced for the height of 8 stories to facilitate that period of free fall acceleration due to buckling. Otherwise the building would've been in free fall for a much shorter period of time - only as much as the height of the unbraced buckled column would allow. It is also necessary for the columns to fail within a fraction of the second of each other to explain the motion of the roof that is observed.
You seem to have forgotten already that the entire core was already collapsing BEFORE there was any "free fall" (in scare quotes, because that motion was never ever really "free" fall - more forces than just gravity acted on every part of the wall throughout the collapse). Since the perimeter bracing consisted of floor girders connected to the core, and the core was already dropping, ALL of the bracing had ALREADY been removed. The girders were now a liability - a problem causing the buckling rather than a measure preventing it.

I am, but would you not agree that a failure of the northern side of the building would drop that side first?
No, I most certainly disagree: Since the northern side failed last, I clearly would expect to drop last. I am at a complete loss what train of thought led you to this strange idea.

Occam's Razor is not an arbiter of truth, it's tendency of simpler explanations being the correct one.
I agree, but it is a good heuristic guidance to establish a null-hypothesis. The null hypothesis is the one that explains most of the observed data with known facts.

In either case, according to Dr. Sunder of NIST, WTC7 failure was a unique event, first of it's kind; furthermore it is still true that historically no steel frame building experienced a complete collapse due to fires. Those considerations would point Occam's Razor towards the CD hypothesis almost automatically, if we look solely at the WTC7 without going through the whole 9/11. [off topic gish gallop removed by Deirdre]

*Edited for clarity
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I am glad Deirdre removed the off topic gish gallop. Just one remark on the bit left standing:
You are - again - wrong, plain and simple. It is NOT true any longer that that historically no steel frame building experienced a complete collapse due to fires. First, many many many steel frame buildings collapse due to fire all the time. Perhaps you meant to include the qualifier "high-rise"? Then this is no longer true, as the collapse of the 15-story Plasco building in Teheran this January has been determined as the result of fires.
 
User @Tony Szamboti, an engineer associated with AE911Truth, made the following post on reddit:


Standando, given the eight story free fall, the explosives/incendiaries in WTC 7 were most likely placed on eight stories of the core columns and detonated in three zones. The zones would be the center and two ends of the core. The center would have been detonated a fraction of a second before the ends to set up the inward pull to keep the falling mass in the building's footprint.

The thermal centroid, that Dr. Hulsey was talking about in his presentation, would not be germane as to which columns would need to be removed. That had to do with horizontal stiffness and thermal movement.

There would be no need for cutting the exterior columns, as taking out eight stories of the core would eliminate lateral support for about 117 feet of the exterior columns and also be pulling them inward. In that situation the exterior columns would exhibit little to no resistance. At 3:10 into his interview here https://www.youtube.com/watch?v=0f4w8iJmn08 (YT: Danny Jowenko - Demolition Expert on WTC7), Danny Jowenko says there would be no need for cutting the exterior columns. When the reporter shows him a plan view he points to the core columns and says these are all that need to be removed. He reiterates this later when he says that he had already explained there was no need to cut the exterior columns.
Content from External Source
(Archived.)

As far as I know, this is the first time someone closely associated with AE911Truth has admitted that the free fall period could happen as the exterior columns lost lateral support and buckled. Of course, Tony believes that happened as a result of a series of (silent and fire proof) high explosives across 8 stories of the core of the building, several of which were subjected to large, travelling fires, while NIST believes, consistent with the visual and audio record, that such column buckling happened as a result of the core failing east to west first in a fire-induced progressive collapse. In any case, perhaps seeing a prominent truther explain how column buckling is consistent with the free fall period for the portion of the northern wall will help other truthers see as bunk the claim that only a controlled demolition could allow for a period of free fall acceleration for that portion of the building. The next question for those truthers to ask themselves is whether it is more likely that there were silent explosives that survived on several consecutive fire-filled floors, or whether, consistent with the audio and visual record, the core collapsed progressively east to west without the aid of any such silent and fire-proof explosives, which then allowed the exterior columns to buckle.
 
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As far as I know, this is the first time someone closely associated with AE911Truth has admitted that the free fall period could happen as the exterior columns lost lateral support and buckled.

I'll let Tony answer that, but I suspect he's admitted it before. It's a shame though that AE911 continues to insist that the exterior could not have fallen without the columns being cut. They make much of "free fall", but as Tony points out all that means is that interior has to collapse before the exterior, which is exactly what we see.

The root problem here is that 9/11 Truthers say the collapse AFTER the first downwards roofline movement looks like a controlled demolition, and they use that as their primary argument. But really they have to show that the collapse BEFORE the first roofline movement is only consistent with a controlled demolition. That is much harder to do, as it's largely unseen, and hence AE911 has for years ignored this portion.
 
I'll let Tony answer that, but I suspect he's admitted it before. ...
Yes, he has. two, three years ago at least, perhaps he's always held that opinion. Need I find a reference? I'd have to search across three forums and inside badly cluttered threads...

ETA: Ok, that was easy after all - I remembered my old habit of occasionally tagging a post with the word "oystein bookmark" (without the blank :D) if I think I need it for future reference. Here it is:
http://www.internationalskeptics.co...ghlight=oysteinbookmark+szamboti#post10980222
Quote Tony Szamboti 2015/11/15:
8 stories of free fall acceleration, that NIST never explained, can certainly be explained by taking out 8 stories of core columns. There is no need to put charges on the exterior columns. They will be pulled inward by the core and buckle with little resistance due to the loss of lateral support for 8 stories and the eccentricity caused by the inward pull. I have done the calculations for this and it would also replicate the observations where there is no deformation of the exterior up high like the NIST model shows.
Content from External Source
 
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I'll let Tony answer that, but I suspect he's admitted it before. It's a shame though that AE911 continues to insist that the exterior could not have fallen without the columns being cut. They make much of "free fall", but as Tony points out all that means is that interior has to collapse before the exterior, which is exactly what we see.

The root problem here is that 9/11 Truthers say the collapse AFTER the first downwards roofline movement looks like a controlled demolition, and they use that as their primary argument. But really they have to show that the collapse BEFORE the first roofline movement is only consistent with a controlled demolition. That is much harder to do, as it's largely unseen, and hence AE911 has for years ignored this portion.

As shown here, I have explained several times that there was no need to set charges on the exterior columns to produce the observed collapse of WTC 7.

However, the NIST WTC 7 report's progressive collapse of the interior from east to west cannot explain the observed simultaneous fall of all four corners of the exterior roofline.

If the east side interior went down first and the interior then collapsed east to west progressively, as NIST claims, there would have been dramatic deformation of the exterior at the top of the building on the east side first, due to the columns buckling under their own weight when lateral support is lost there for about 15 to 20 stories. While this is observed in the NIST model, it is not in reality.

There is a good deal of evidence that the east penthouse only went down into the top stories of the main building.

1. Daylight is only observed at the top story windows.
2. The shock wave goes top to bottom.
3. Windows are only broken from the roof down about 15 stories.
4. There is no exterior deformation of the exterior columns on the east side.
5. Dust is not seen emanating from the east side until the entire exterior is falling.

The only explanation which would produce the observed behavior of the exterior is that the full core was still there for most of the height of the building after the east penthouse fell and the core then went down nearly simultaneously pulling the entire exterior inward low in the building for about 8 stories. Most probably on floors 14 through 21 which had no fires, except on floor 19.
 
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If the east side interior went down first and the interior then collapsed east to west progressively, as NIST claims, there would have been dramatic deformation of the exterior at the top of the building on the east side first, due to the columns buckling under their own weight when lateral support is lost there for about 15 to 20 stories. While this is observed in the NIST model, it is not in reality.

Define "dramatic" here? What's the range of possible outcomes, and how did you determine them?
 
I am not aware of evidence that all four corners of the roof started to descend at the same time (which, in the days of 30 fps video, I'd expect to see defined as "within less than 1/30 of a second"). Tony?

Also, it seems strange to consider the EPH collapse as wholly unrelated to the main collapse. I remember Tony speculating years ago that this was done to prevent the collapse from damaging surrounding property, but neither was a mechanism proposed why that should have worked, nor did it work, as WTC7, far from collapsing "into its footprint", crossed streets on at least two sides and incurred major damage to at least 3 buildings, one of which was a total loss.
 
Define "dramatic" here? What's the range of possible outcomes, and how did you determine them?
I did a finite element analysis of the east wall without lateral support. The columns have their flanges normal to the exterior girders and the weak axis is in the east to west direction and the buckling goes that way once about 15 stories are without lateral support. The movement I got was similar to what is seen in the NIST 47 story model. However, this is not what is observed.
 
If the east side interior went down first and the interior then collapsed east to west progressively, as NIST claims, there would have been dramatic deformation of the exterior at the top of the building on the east side first, due to the columns buckling under their own weight when lateral support is lost there for about 15 to 20 stories.

The East side of WTC7 does distort more than the west side. But the major bucking happens on lower floors that are far out of sight.
WTC-7-sagging-loop.gif
(East is on the left here)


And it seems a bit much to be dismissing the NIST simulations and also suggesting that they are perfectly accurate. As you know the models were to investigate collapse initiation, not a visually accurate progression. They had several limitations, which NIST addressed:

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

29. The simulation of the collapse modeling of WTC 7 does not match the video footage of the collapse. In particular, the large inward deformations of the upper exterior walls after the beginning of global collapse are not visible in the video footage. Can NIST explain the difference between the results of its computer model of the collapse and the available video evidence?

NIST conducted two global collapse analyses, one that included damage due to debris-impact from the collapse of WTC 1, and one that did not include any debris-impact damage. These two analyses were conducted to determine the influence of the debris-impact damage on the response of WTC 7 when subjected to the effects of the fires that burned on floors 7 to 9 and 11 to 13. In its comparison of the two analyses (see NIST NCSTAR 1A Section 3.5), NIST showed that the analysis with the debris-impact damage better simulated the sequence of observed events, and it is this simulation that is considered here.

NIST believes that the simulation of the collapse, based on the analysis with debris-impact damage, does capture the critical observations derived from the digital video recording. The critical observations and corresponding failures identified in the structural analysis include: 1) east-west motion of the building beginning at approximately the same time as failure of floors 6 through 14 around Column 79, 2) the formation of the "kink" in the roofline of the east penthouse approximately one second after Column 79 was found to buckle, 3) window breakage on the east side of the north face as the buckling of Column 79 precipitated the failure of upper floors, and 4) the beginning of global collapse (vertical drop of the building exterior) within approximately one-half second of the time predicted by analysis. Both measured time and analytically predicted time, from the start of failures of floors surrounding Column 79 to the initial downward motion of the north face roofline, was 12.9 seconds (see NIST NCSTAR Report 1A, Table 3-1). The collapse observations, from video analysis of the CBS News Archive video, are covered in detail in NIST NCSTAR Report 1A Section 3.5 and NIST NCSTAR Report 1-9, Section 8.3. Only in the later stages of the animation, after the initiation of global collapse, do the upper exterior wall deformations from the NIST analysis differ from the video images.

Uncertainties associated with the approach taken by NIST are addressed in NIST NCSTAR Report 1A, Section 3.5, where it is noted, "Once simulation of the global collapse of WTC 7 was underway, there was a great increase in the uncertainty in the progression of the collapse sequence, due to the random nature of the interaction, break up, disintegration, and falling debris." The contribution to stiffness and strength of nonstructural materials and components, such as exterior cladding, interior walls and partitions, was not considered in the analyses conducted by NIST. It is well known that such non-structural components can increase the stiffness and strength of a structural system, but their contribution is difficult to quantify. Given these factors, disparities between the video and the animation in the later stages of collapse would be expected.
Content from External Source
 
I did a finite element analysis of the east wall without lateral support. The columns have their flanges normal to the exterior girders and the weak axis is in the east to west direction and the buckling goes that way once about 15 stories are without lateral support. The movement I got was similar to what is seen in the NIST 47 story model. However, this is not what is observed.

Where is this? And how can you model the wall in isolation? The exterior forms a tube.
 
I am not aware of evidence that all four corners of the roof started to descend at the same time (which, in the days of 30 fps video, I'd expect to see defined as "within less than 1/30 of a second"). Tony?

Also, it seems strange to consider the EPH collapse as wholly unrelated to the main collapse. I remember Tony speculating years ago that this was done to prevent the collapse from damaging surrounding property, but neither was a mechanism proposed why that should have worked, nor did it work, as WTC7, far from collapsing "into its footprint", crossed streets on at least two sides and incurred major damage to at least 3 buildings, one of which was a total loss.
Where is this? And how can you model the wall in isolation? The exterior forms a tube.
You can certainly model the wall in isolation to see when buckling under the column's own weight would occur, which is what happens if there is no lateral support. The north and south walls will not provide enough support to help the columns in the middle of the east wall. There is a real problem with the explanation you and others want to support here with the east side interior allegedly coming down first but no deformation of the east exterior first.
 
The East side of WTC7 does distort more than the west side. But the major bucking happens on lower floors that are far out of sight.
WTC-7-sagging-loop.gif
(East is on the left here)


And it seems a bit much to be dismissing the NIST simulations and also suggesting that they are perfectly accurate. As you know the models were to investigate collapse initiation, not a visually accurate progression. They had several limitations, which NIST addressed:

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

29. The simulation of the collapse modeling of WTC 7 does not match the video footage of the collapse. In particular, the large inward deformations of the upper exterior walls after the beginning of global collapse are not visible in the video footage. Can NIST explain the difference between the results of its computer model of the collapse and the available video evidence?

NIST conducted two global collapse analyses, one that included damage due to debris-impact from the collapse of WTC 1, and one that did not include any debris-impact damage. These two analyses were conducted to determine the influence of the debris-impact damage on the response of WTC 7 when subjected to the effects of the fires that burned on floors 7 to 9 and 11 to 13. In its comparison of the two analyses (see NIST NCSTAR 1A Section 3.5), NIST showed that the analysis with the debris-impact damage better simulated the sequence of observed events, and it is this simulation that is considered here.

NIST believes that the simulation of the collapse, based on the analysis with debris-impact damage, does capture the critical observations derived from the digital video recording. The critical observations and corresponding failures identified in the structural analysis include: 1) east-west motion of the building beginning at approximately the same time as failure of floors 6 through 14 around Column 79, 2) the formation of the "kink" in the roofline of the east penthouse approximately one second after Column 79 was found to buckle, 3) window breakage on the east side of the north face as the buckling of Column 79 precipitated the failure of upper floors, and 4) the beginning of global collapse (vertical drop of the building exterior) within approximately one-half second of the time predicted by analysis. Both measured time and analytically predicted time, from the start of failures of floors surrounding Column 79 to the initial downward motion of the north face roofline, was 12.9 seconds (see NIST NCSTAR Report 1A, Table 3-1). The collapse observations, from video analysis of the CBS News Archive video, are covered in detail in NIST NCSTAR Report 1A Section 3.5 and NIST NCSTAR Report 1-9, Section 8.3. Only in the later stages of the animation, after the initiation of global collapse, do the upper exterior wall deformations from the NIST analysis differ from the video images.

Uncertainties associated with the approach taken by NIST are addressed in NIST NCSTAR Report 1A, Section 3.5, where it is noted, "Once simulation of the global collapse of WTC 7 was underway, there was a great increase in the uncertainty in the progression of the collapse sequence, due to the random nature of the interaction, break up, disintegration, and falling debris." The contribution to stiffness and strength of nonstructural materials and components, such as exterior cladding, interior walls and partitions, was not considered in the analyses conducted by NIST. It is well known that such non-structural components can increase the stiffness and strength of a structural system, but their contribution is difficult to quantify. Given these factors, disparities between the video and the animation in the later stages of collapse would be expected.
Content from External Source
It is only rotation you see there, not buckling of the exterior columns as you should see once lateral support is removed at the top in the NIST allegation of full east side interior collapse first. The rotation to the north was caused by the north wall being cracked about 80 to 100 feet towards the west from the northeast corner.

The NIST 47 story model shows column buckling at the top of the building due to loss of lateral support, but that is not evident in the video.
 
You can certainly model the wall in isolation to see when buckling under the column's own weight would occur, which is what happens if there is no lateral support. The north and south walls will not provide enough support to help the columns in the middle of the east wall. There is a real problem with the explanation you and others want to support here with the east side interior allegedly coming down first but no deformation of the east exterior first.
You quoted me in full, but then went on to not address a single word I said.

I had said:

I am not aware of evidence that all four corners of the roof started to descend at the same time (which, in the days of 30 fps video, I'd expect to see defined as "within less than 1/30 of a second"). Tony?

Also, it seems strange to consider the EPH collapse as wholly unrelated to the main collapse. I remember Tony speculating years ago that this was done to prevent the collapse from damaging surrounding property, but neither was a mechanism proposed why that should have worked, nor did it work, as WTC7, far from collapsing "into its footprint", crossed streets on at least two sides and incurred major damage to at least 3 buildings, one of which was a total loss.
 
You quoted me in full, but then went on to not address a single word I said.

I had said:

I am not aware of evidence that all four corners of the roof started to descend at the same time (which, in the days of 30 fps video, I'd expect to see defined as "within less than 1/30 of a second"). Tony?

Also, it seems strange to consider the EPH collapse as wholly unrelated to the main collapse. I remember Tony speculating years ago that this was done to prevent the collapse from damaging surrounding property, but neither was a mechanism proposed why that should have worked, nor did it work, as WTC7, far from collapsing "into its footprint", crossed streets on at least two sides and incurred major damage to at least 3 buildings, one of which was a total loss.
I didn't think it deserved a response as every aerial video of the collapse of WTC 7 shows all four of its roofline corners start to descend simultaneously. It is silly to deny it, but it looks like you are trying to do so.
 
Tony, there is nothing to deny. I apply Hitchen's Razor: That which is asserted without evidence can be rejected without evidence. Besides, it is silly to assert that any video even just shows all four corners.

I also made two completely distinct comments. You quoted them twice, but never addressed the bit about the EPH collapse being partial and unrelated to the main collapse.
 
Tony, forgive me for paraphrasing here, but it sounds to me like you're arguing that the observed collapse is perfectly consistent with interior column failure, BUT, because you believe that NISTs probable point of collapse initiation was not the actual point of initiation, that only CD could have brought the building down in the observed manner.

Surely you see this is a non sequitor? Have you ruled out all other potential failure modes? Have you provided any evidence of explosives or explosions? (I recognize there is anecdotal evidence of explosion-like sounds, but big bangs can have other causes, too)
 
Tony, forgive me for paraphrasing here, but it sounds to me like you're arguing that the observed collapse is perfectly consistent with interior column failure, BUT, because you believe that NISTs probable point of collapse initiation was not the actual point of initiation, that only CD could have brought the building down in the observed manner.

Surely you see this is a non sequitor? Have you ruled out all other potential failure modes? Have you provided any evidence of explosives or explosions? (I recognize there is anecdotal evidence of explosion-like sounds, but big bangs can have other causes, too)
A progressive collapse starting on the east side would have generated east side exterior column deformation as one does see in the NIST model. However, that is not what is seen in the actual collapse, because it did not happen the way NIST wants to claim. This 51 second clip will show you the NIST model vs. the actual collapse.


Source: https://www.youtube.com/watch?v=LMeXKNWcbew


The behavior of the building actually shows it was internal column failure that initiated the collapse, but it had to be the entire central core that failed simultaneously (not east to west progressively) to bring all four corners of the building down simultaneously.

There is no non sequitur in this argument. It was the internal columns, but it wasn't a single column and an east side, then east to west, progressive collapse that caused it. The lack of east side exterior column deformation first, in conjunction with an alleged east side interior collapse, in the real collapse, is proof of that.
 
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The behavior of the building actually shows it was internal column failure that initiated the collapse, but it had to be the entire central core that failed simultaneously (not east to west progressively) to bring all four corners of the building down simultaneously.

You are not really providing any numerical evidence of this. NIST explained why their simulation differed.
 
The next question for those truthers to ask themselves is whether it is more likely that there were silent explosives that survived on several consecutive fire-filled floors, or whether, consistent with the audio and visual record, the core collapsed progressively east to west without the aid of any such silent and fire-proof explosives, which then allowed the exterior columns to buckle.

Not only would the silent explosives themselves have to be fireproof; so would the electrical connections (wired or wireless) that initiate each charge's explosion, in proper sequence. Otherwise there would have been a strong possibility of a failed demolition.

I have witnessed such a failure myself, in the demolition of a tower block in Hackney, London. The lower part of the block disintegrated, but the upper half he'd together and ended up resting on top of the conical mound of debris. This left the difficult and dangerous task of rigging a second demolition (edit: by ball and chain, not explosives, in the case) within a highly damaged structure, as well as much embarrassment for the demo contractors.

Of course, in the WTC 7 case, there would have been a considerable risk to the supposed conspirators that their CD preparations would be found in the event of a failed demolition.

And in that context I don't think it is too off topic to remind the CD advocates that such a failure would only exacerbate the existing risk that the rigging for control demolition might be discovered before the initiation of the whole attack.

And for what benefit to the alleged conspirators? Demolition WTC 7 (in a way that CD conspiracy advocates claim themselves was a highly suspicious manner) would add nothing to the pretext for war already provided by the destruction of the Towers, but would have greatly increased the danger of exposure for the conspirators.

It just makes no sense.
 
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A progressive collapse starting on the east side would have generated east side exterior column deformation as one does see in the NIST model. However, that is not what is seen in the actual collapse, because it did not happen the way NIST wants to claim. This 51 second clip will show you the NIST model vs. the actual collapse.


Source: https://www.youtube.com/watch?v=LMeXKNWcbew


The behavior of the building actually shows it was internal column failure that initiated the collapse, but it had to be the entire central core that failed simultaneously (not east to west progressively) to bring all four corners of the building down simultaneously.

There is no non sequitur in this argument. It was the internal columns, but it wasn't a single column and an east side, then east to west, progressive collapse that caused it. The lack of east side exterior column deformation first, in conjunction with an alleged east side interior collapse, in the real collapse, is proof of that.


This argument now boils down to because NIST's high level collapse simulation (based on a whole series of clearly stated assumptions and simplifications and path dependent calculations based on the same) showed a few differences compared to the actual collapse event in how the relatively small visible area of the northern face distorted during such simulation, we must conclude explosives must have been necessary to cause the actual collapse event.

Tony--you surely can see how your conclusion does not follow from your premise, and none of the work you claim to have done (but haven't shared) re modeling a wall would fill the logical gap between your conclusion and premise. You are ignoring NIST's explanation (and the clear visual evidence for the east-to-west progressive collapse) and merely asserting what is actually a very complex technical argument as if it were established fact. But you never established any of the claims you are making re how the building would have to behave in any given progressive collapse scenario. In fact, it's clear that you haven't even really taken the first step in analyzing the problem as you have failed to respond to Mick above as to how you would even define the distortion condition that could only be caused by controlled demolition.
 
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NIST showed two different LS-DYNA runs: One without, and one with North Tower impact damage.
The one without impact damage contorted a lot more than the one with.

Which shows that whether, and how much, the structure bends, twists and contorts is sensitive to input conditions such as the extent and nature of impact damage.

Of course, with limited photo and video documentation of all sides of the building, the damage pattern is only imprecisely known, and we can be quite certain that NIST's best assumptions do not fit reality prefectly.

Hence, given the demonstrated sensitivity of the output relative to the input, it cannot surprise in the least that output deviates noticably from reality.


Now mark this: When model output conflicts with reality, do not throw reality out the window!

At the end of the day there is no evidence of CD and no need for CD.
If Tony wants to convince us that all 24 core columns were cut simultaneously - and absent any qualification we must assume: at literally the exact same moment, down to better than a millisecond accuracy - he is telling us that "nano-thermite" or any other "incendiaries" are out of the question - it must have been high explosives.
We know, because NIST computed it, that column 79 alone would have required 9 pounds of high explosives. Let's say all columns averaged 5 pounds. But wait: Aren't we told that columns were destroyed over a length of 8 floors? Does that mean 9 charges per column? Or perhaps 5? We are talking about 120 or 240 cherges of 5 pounds each - 600 to 1200 pounds total - all exploding at once.

Silently.

Ponder that.
 
This argument now boils down to because NIST's high level collapse simulation (based on a whole series of clearly stated assumptions and simplifications and path dependent calculations based on the same) showed a few differences compared to the actual collapse event in how the relatively small visible area of the northern face distorted during such simulation, we must conclude explosives must have been necessary to cause the actual collapse event.

Tony--you surely can see how your conclusion does not follow from your premise, and none of the work you claim to have done (but haven't shared) re modeling a wall would fill the logical gap between your conclusion and premise. You are ignoring NIST's explanation (and the clear visual evidence for the east-to-west progressive collapse) and merely asserting what is actually a very complex technical argument as if it were established fact. But you never established any of the claims you are making re how the building would have to behave in any given progressive collapse scenario. In fact, it's clear that you haven't even really taken the first step in analyzing the problem as you have failed to respond to Mick above as to how you would even define the distortion condition that could only be caused by controlled demolition.
Bentham, you seem to be so pre-occupied with saying everything is too complex to figure out, that you failed to realize that I said the severe deformation of the east wall exterior columns would have to occur in a natural scenario when the east interior comes down.

The NIST model shows this deformation because they are pretending it is natural and removing the east interior. In reality, the east interior is not gone and that is why we don't see the exterior deformation as shown in the NIST model. I am speaking of the buckling of the columns at the top in their model, which Mick didn't seem to think could happen as he thought the fact that it was a tube would make a difference. I explained to him that the tube was quite wide and the north and south walls would not have much of an effect on most of the columns of the east wall.

The lack of east exterior wall deformation high in the building in the real collapse is because the east side interior did not collapse the way NIST claims. That is a fairy tale and the structural behavior proves it. I haven't seen anyone who supports the NIST WTC 7 report conclusions have an answer for it.

I also want to complain about how long it takes for my posts to appear. The last one took about 12 hours. I can't deal with that and then respond quickly. This site was not like that before and this large wait time is a real drag on the discussion.
 
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