Debunked: NIST computer simulation of Building 7 collapse is inaccurate

... Has all the input data files released so universities and other knowledgeable people can run the simulation themselves and see how it was built. I don't buy the argument that this would jeopardize public safety at all.
(Apologies to the group for the sidebar) Are you aware that sufficient information exists about the construction of WTC 7 to create one's own FEA model (if one has the time and software to do so) and that this has been done by others?

I personally also scratch my head at the public safety argument, but it doesn't change the fact that people with appropriate engineering knowledge can make an FEA of WTC 7 even without NIST's input data. I would in fact expect a competent forensic SE to be able to do exactly this with all of the published information available.
 
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Oystein

Senior Member
I didn't bring up Hulsey, and almost never do, since that report has very little bearing on me believing what I do. So I don't really know why you keep bringing it up.

You're implying I want the simulation to be an absolutely perfect match, and nothing less will do. That's not what I think, so let me clarify what I would want. I'd like to see a simulation that:

1) Runs from the start of the collapse to the end, not cutting in the middle. The fall should be relatively smooth, like it was in real life.

2) Can be shown to achieve some amount of g acceleration of the roofline. It doesn't have to be the exact 2.25 seconds NIST identified as their "Stage 2", I'm fine with less than that.

3) Has all the input data files released so universities and other knowledgeable people can run the simulation themselves and see how it was built. I don't buy the argument that this would jeopardize public safety at all.

I don't think these are too unreasonable.
Please present engineering reasons to support the insinuation that each point 1) through 3) (point 1 is actually two points) is required to fullfill NIST's objectives and help us understand why WTC7 collapsed, and how to prevent such occurrences in the future!
 

Mendel

Senior Member.
Please present engineering reasons to support the insinuation that each point 1) through 3) (point 1 is actually two points) is required to fullfill NIST's objectives and help us understand why WTC7 collapsed, and how to prevent such occurrences in the future!
these 3 points don't have anything to do with NIST's objectives, they're simply @Henkka's personal "I'd like to see". Which is why I've called his post a derail of the topic (in #40).
 

Henkka

Banned
Banned
Please present engineering reasons to support the insinuation that each point 1) through 3) (point 1 is actually two points) is required to fullfill NIST's objectives and help us understand why WTC7 collapsed, and how to prevent such occurrences in the future!
I'm not an engineer though, just a random member of the public who doesn't find NIST's explanation of the collapse convincing. Points 1) and 2) are about showing that their explanation could plausibly happen in reality, and point 3) is to make sure they're not fudging the simulation to come out the way they want.
these 3 points don't have anything to do with NIST's objectives, they're simply @Henkka's personal "I'd like to see". Which is why I've called his post a derail of the topic (in #40).
Oystein seemed to be saying I'm demanding the simulation to be an exact 1:1 match, so yeah, I clarified what I'd like to see.
 

LilWabbit

Senior Member
Oystein seemed to be saying I'm demanding the simulation to be an exact 1:1 match, so yeah, I clarified what I'd like to see.

The validity of a model or a piece of evidence from an engineering perspective is independent of what a (self-acknowledged) non-engineer would "like" to see as a model or as evidence. Or what an engineer committed to a truther theory would "like" to see.

For your counter-arguments to carry weight @Henkka, the onus is on you to demonstrate how the NIST simulations were either motivated or not fit for the specific purposes they were designed. Reiterating they didn't match the exact progression of the actual collapse fails to do that no matter how well you, or truther engineers, analyze and describe that mismatch.
 

Mendel

Senior Member.
I'm not an engineer though, just a random member of the public who doesn't find NIST's explanation of the collapse convincing.
The thing that astounds me is that you find the CD idea more convincing despite a complete lack of evidence.
 

Landru

Moderator
Staff member
The thing that astounds me is that you find the CD idea more convincing despite a complete lack of evidence.
This is not an invitation to discuss evidence of controlled demolition in this thread. Posts discussing CD will be suspended from this thread.
 

Oystein

Senior Member
I'm not an engineer though, just a random member of the public
Yes.
who doesn't find NIST's explanation of the collapse convincing.
It suffices when, oh, 98% of the engineers that matter are persuaded. Like all the engineeres uprading codes, the engineers writing textbooks, the engineering professors teaching the current paradigms of structural engineering, etc etc etc

Points 1) and 2) are about showing that their explanation could plausibly happen in reality,
Or so you, a non-engineer random member of the public IMAGINE.
But why do you think this is so?

and point 3) is to make sure they're not fudging the simulation to come out the way they want.
Do you believe (find it more plausible or likely than not) that the NIST simulations are "fudged"?
If so: In what way? What specific evidence informs your belief?

Oystein seemed to be saying I'm demanding the simulation to be an exact 1:1 match, so yeah, I clarified what I'd like to see.
You picked out some random detail features that you believe to be relevant.
Or, well, no, that is not quite true: You BELIEVED 9/11 Truthers who picked out some random detail features for you and made you BELIEVE to be relevant.
You need to explain why you think they are relevant. You might as well have picked any out of a million other details (and likely they would not show up in NIST's animation, for it is expected, unavoidable that the simulation will differ in many many many details from reality, because such is the nature of complex simulations).
 

Mendel

Senior Member.
Let's consider a metaphor that applies to this topic (accuracy of the simulation)

I am baking a muffin.
You taste this muffin, and say "Grandma's muffin tasted different in some ways".
You conclude that I did not, in fact, bake a muffin.

Does this seem reasonable to you?
If not, why not?


You demand that I bake a muffin that has the exact same crumbliness and sweetness as your grandma's muffin, and expect me to publish my recipe (for you to check).

How am I going to react?

Some bakers taste my muffins and seem satisfied with them.

Does that mean anything?
 
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Henkka

Banned
Banned
Do you believe (find it more plausible or likely than not) that the NIST simulations are "fudged"?
If so: In what way? What specific evidence informs your belief?
I think these questions are going off-topic... The topic is about whether or not the NIST simulation visually resembles the real collapse. And as far as I can tell, the two camps are:

"No, and that's a reason to distrust the simulation" (This would be me), and

"No, but it doesn't matter" (Everyone else here)

I don't really see anyone besides the OP, who doesn't seem to be active here anymore, claiming the NIST simulation "closely resembles" the real collapse. So I don't really agree the claim in the thread title is "debunked", but I do agree the documentary presented the wrong simulation.
 

Henkka

Banned
Banned
By the way, here's a question relating to the simulation cutting abruptly... Can you predict what happened next to this building from this gif?



Some here probably know this building, it's the failed demolition of the Zip Feed mill in South Dakota. Immediately after I cut the gif, the collapse arrested and the building stayed there as a leaning tower. This hopefully demonstrates my problem with cutting the simulation... You can't just show the very beginning of a collapse and them imply it would continue smoothly all the way to the ground. You can't possibly know that it would.
 

econ41

Senior Member
I think these questions are going off-topic... The topic is about whether or not the NIST simulation visually resembles the real collapse. And as far as I can tell, the two camps are:

"No, and that's a reason to distrust the simulation" (This would be me), and
Yes - the topic has been forgotten. And I fully understand the concerns that you have. The NIST simulation does NOT "look like" the real event. And, from my perspective, truthers who have genuine concerns warrant a reasoned explanation. The gross motions as shown by the NIST sims "seem" to be orders of magnitude beyond the ductility limits of a steel frame. I may be wrong because I cannot be bothered to spend the energy to read the whole background. So be it.

I've outlined my reasons and they have been generally ignored or disagreed with. I think we have an "Elephant In The Room".
"No, but it doesn't matter" (Everyone else here)
Please don't take my lack of comments as disinterest and don't include me in "Everyone else". I haven't pushed the issue because I see the whole topic as irrelevant. So not worth the effort to argue it >> and pushing the debate into what most would see as "Off Topic". I actually think the distinction between "engineering quantified modelling" and "look-alike explanatory models" (Or simulations) is fundamental. Other members don't. Whether it is "inaccurate" or not the NIST simulation is certainly misleading to laypersons who have limited knowledge of modelling or simulation techniques.
I don't really see anyone besides the OP, who doesn't seem to be active here anymore,
He isn't
claiming the NIST simulation "closely resembles" the real collapse.
It doesn't
So I don't really agree the claim in the thread title is "debunked",
It isn't.

but I do agree the documentary presented the wrong simulation.
Yes. but that is a separate issue.
 
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econ41

Senior Member
By the way, here's a question relating to the simulation cutting abruptly... Can you predict what happened next to this building from this gif?


This hopefully demonstrates my problem with cutting the simulation...
I understand your problem.
You can't just show the very beginning of a collapse and them imply it would continue smoothly all the way to the ground.
Almost certainly true because.....
You can't possibly know that it would.
Unless you are a competent person - probably an engineer - and have sufficient coverage of the facts to support a valid prediction. I could not guasrantee a prediction either way on the basis of the clipped video - even if I had the full set of structural drawings.
 

Mendel

Senior Member.
This hopefully demonstrates my problem with cutting the simulation... You can't just show the very beginning of a collapse and them imply it would continue smoothly all the way to the ground. You can't possibly know that it would.
But we know that it did.

What nobody knew before 9/11 was how it was possible for a steel-frame skyscraper to totally collapse from fire. The simulation showed that "settled science" in the form of established software packages for fire modeling and structural analysis predicted a collapse from fire in this scenario—as have other independent analyses.

It is obvious from the 9/11 observations that, once gross collapse had initiated, it became total.
It was not obvious how that initiation happened because the important stuff happened inside a burning building where nobody could monitor it—hence the need for a simulation.

The purpose of the simulation is not to convince anyone that something for which there is no evidence did not happen. NIST explains what the evidence that exists means, and the simulation is part of that.
 
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LilWabbit

Senior Member
I think these questions are going off-topic... The topic is about whether or not the NIST simulation visually resembles the real collapse. And as far as I can tell, the two camps are:

"No, and that's a reason to distrust the simulation" (This would be me)

But your distrust still assumes the purpose of the simulation is visual resemblance. As has been pointed out to you on this thread a few times, it wasn't. So why do you continue basing your distrust on misinformation?

The real question is: Do you have a valid reason to distrust the simulation after you have acquainted yourself properly with what it was actually designed to demonstrate and how? I suggest the answer is 'no'.

Let me kindly remind you that we're stuck in an impasse because you refuse to do the said 'acquainting'. You continue to assume something that's simply not true (i.e. 'the purpose of the NIST simulation is visual resemblance' and 'the only valid kind of simulation is one that bears visual resemblance'), and refuse to budge even after correction. Only to fall back to repeating your initial criticism with different wording.
 

Henkka

Banned
Banned
But your distrust still assumes the purpose of the simulation is visual resemblance. As has been pointed out to you on this thread a few times, it wasn't. So why do you continue basing your distrust on misinformation?
Shyam Sunder:
Here's our structural model showing the building collapsing, which matches quite well... with the video of the event.
16:40 https://www.c-span.org/video/?280569-1/investigation-world-trade-center-building-7

Why's he talking about how well it matches, if that wasn't their intention?
 

LilWabbit

Senior Member
Shyam Sunder:

16:40 https://www.c-span.org/video/?280569-1/investigation-world-trade-center-building-7

Why's he talking about how well it matches, if that wasn't their intention?

"Quite well" is a very apt choice of words. There were two simulations, remember (OP)? The one in your linked video is the one which bore closer resemblance to the actual collapse and which David Hooper chose not to feature in his truther video. Why isn't such a seemingly calculated omission more suspect?

The intention (the resident MB engineers correct me if I'm missing something out) of one of the NIST simulations was to see if a fire could initiate a total collapse of the WTC 7. The intention of the other (featured in your video) was to see how the collapse looked if debris impact damage is included in the simulation. The one including the debris impact resembled the actual collapse "quite well" as compared to the other one which excluded the impact. This fact, by extension, added credence to the hypothesis of a fire-initiated collapse the progression of which was affected by debris impact.

So to recap: The intention of the second simulation including the debris impact was never to achieve a perfectly accurate resemblance, but rather to see if the simulation tends to resemble the real event better when debris impact is added. It did. The simulation served its specific purpose.

Choosing not to trust the simulation because it doesn't resemble the collapse even more accurately is entirely missing the point, and a false assumption for its validity or lack thereof. Especially when a level of mismatch between the simulation and the observed events was anticipated and expected by the NIST owing to the uncertainties cited in @Oystein's earlier post.
 
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Oystein

Senior Member
...
I don't really see anyone besides the OP, who doesn't seem to be active here anymore, claiming the NIST simulation "closely resembles" the real collapse. So I don't really agree the claim in the thread title is "debunked", but I do agree the documentary presented the wrong simulation.
You see me:

I already explained to you in detail why I think that the NIST simulation "closely resembles" the real collapse in all properties and details that matter. But of course you ignored that.
It does not resemble arbitrarily "closely" the collapse in a million details that do not matter.
 

Henkka

Banned
Banned
You see me:

I already explained to you in detail why I think that the NIST simulation "closely resembles" the real collapse in all properties and details that matter. But of course you ignored that.
It does not resemble arbitrarily "closely" the collapse in a million details that do not matter.

So in your mind, it doesn't matter at all whether or not their simulation was able to replicate this motion, which is not shown?

Source: https://imgur.com/a/t10dFrr


Would it change your mind at all if it turned out that they did try to simulate this part as well, but could not get it to match?
 

LilWabbit

Senior Member
Would it change your mind at all if it turned out that they did try to simulate this part as well, but could not get it to match?

This above response shows you're still ignoring the following point reiterated by @Oystein:

"I already explained to you in detail why I think that the NIST simulation "closely resembles" the real collapse in all properties and details that matter."

NIST:

Article:
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.


In other words, whether or not NIST tried to simulate an even more accurate match, failure to do so would not invalidate the key conclusions of the simulation which were based on these four (4) critical observations:

Article:
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.


You're still subscribing to the misinformation that an exact match is necessary for the simulation to validly yield the conclusion of a fire-induced initiation of the WTC 7 collapse the progression of which was affected be debris impact.
 

Mendel

Senior Member.
I think one of things that get overlooked here is that the accuracy of the simulation compared to the actual events doesn't validate our idea of the 9/11 events, it validates the simulation.

With any computer model, especially when modelling a big, complex system, it must be assumed that the model must be flawed, because it never matches reality exactly. (Does your credit score actually reflect your credit risk accurately?) The fact that the simulation comes pretty close means that the simulation is pretty good.

If the match had been worse, it wouldn't have been a problem with reality, it would've been a flaw of the simulation.

Any perceived mismatch or lack of accuracy won't prove anything about 9/11, it would just show a problem "with the computer".
 

Abdullah

Active Member
Guys, chill. There is no doubt that the NIST simulation shows striking differences with reality. The inward bowing of the northeast and southwest corners is inaccurate. Nor is the westward tilt of the West penthouse.

But is that really important? That's the question we should be asking. Or can we overlook these errors?

I still advocate for renaming the thread btw.
 

econ41

Senior Member
Guys, chill. There is no doubt that the NIST simulation shows striking differences with reality. The inward bowing of the northeast and southwest corners is inaccurate. Nor is the westward tilt of the West penthouse.

But is that really important? That's the question we should be asking. Or can we overlook these errors?

I still advocate for renaming the thread btw.
At last.
Well said @Abdullah. That is the real issue - the "elephant in the room". Whichever of the NIST simulations they bear little visual resemblance to the real event. The two separate issues identified by the opening sentences of the OP - viz, though the NIST sim(s) are reasonable alternate attempts and are probably as close to reality as NIST needed. So they were (1) "fit for purpose" without any need to argue about the level of accuracy as visual representations. Whilst (2) they bore little visual resemblance to the actual collapse. And we should all be aware of that second reality - it was the basis of the fraudulent simulation produced by Hulsey. With the clear aim of supporting the false belief held by many truthers that a sim MUST "look like the real thing".

The extreme distortions shown by both NIST sims still look to me to be well outside the limits of material ductility. I could be wrong. I guessed, wrongly it seems, back in the first few posts that the reasons were a feature of engineering deliberate choice. That much seems to be true - one sim subject to gross simplification looks less like the real event than the other sim which is more realistic. I just identified the wrong aspect of engineering choice in my first guess. And I've never attempted to fully understand the NIST choices because in most discussions the real contention is over the false truther belief that a valid sim MUST "look like" the real event.

BUT whether the thread is clearly titled or not the underlying issue is that the NIST sims do not look much like the real event. That is the concern that truthers express and was identified in the OP. The NIST sims do not show the neat straight-down dropping of the essentially undamaged perimeter shell which shows little distortion.
 
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