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

Thomas B

Active Member
while the risk may be very remote, the potential damage would be very high and, on other hand, the benefit to releasing those files would be very low.
I'm not sure about this. The risk is indeed remote and the benefit seems obvious: the information could be used to design (and teach the design of) structures that are much less vulnerable to total progressive collapse under accidental loads (like fire and earthquake). Making data available to the whole community of scientists is generally good for science. And what seems to be needed here is more and better science.

I tend to agree with @Henkka that the reticence of DOT to release the data is a red flag about their own confidence in the quality of the data.

(But I think this will need to go in another thread if we want to pursue it.)
 

benthamitemetric

Senior Member
I'm not sure about this. The risk is indeed remote and the benefit seems obvious: the information could be used to design (and teach the design of) structures that are much less vulnerable to total progressive collapse under accidental loads (like fire and earthquake). Making data available to the whole community of scientists is generally good for science. And what seems to be needed here is more and better science.

I tend to agree with @Henkka that the reticence of DOT to release the data is a red flag about their own confidence in the quality of the data.

(But I think this will need to go in another thread if we want to pursue it.)
You are just substituting pure speculation, based on your own bias for conspiracy theory belief (and please spare us the "I'm here to learn how to better debate truthers on other forums" schtick) for evidence, and you are doing so contrary to the only record on this issue we have, which is the DoT's stated reason for the denial, which was not even disputed by the FOIA filer. I thought it worthwhile to debunk the few misstatements of fact re the FOIA denial in Henka's post, but this not an appropriate thread to engage further in baseless speculations about it.
 

Henkka

Active Member
The decision to withhold the data was not even made by NIST. It was made by the Office of the General Counsel to the Department of Transportation, which is the agency that oversees NIST.
The reasoning that the files would jeopardize public safety came from the Director of NIST, as per the FAQ. Whoever declined the FOIA based on that reasoning is irrelevant, the reasoning itself is the issue. And I would hold that the reasoning is absurd.
 

benthamitemetric

Senior Member
I'm siding with @Henkka on the question of whether NIST/DoT's reasoning is absurd. You suggested that there would great (if remote) harm and no benefit to releasing the data. I'm saying there are some obvious benefits.
How does releasing the data to the general public achieve that benefit? The general public is not designing high rise structures and has no need to know how to destroy them. If you can find even one actual structural engineer who works on real world high rise building projects who thinks they need that data in order to improve their designs (and who have directly requested it subject to confidentiality obligations and been denied), then start a new thread about this. You are straining to conjure up a motive for the denial that fits your preconceived notions when there is zero evidence for one.
 

benthamitemetric

Senior Member
The reasoning that the files would jeopardize public safety came from the Director of NIST, as per the FAQ. Whoever declined the FOIA based on that reasoning is irrelevant, the reasoning itself is the issue. And I would hold that the reasoning is absurd.
Ok, I had been relying on the denial letter itself and NIST's FAQ note on this point shows I was mistaken on two points: (i) It was not just the DoT that made the determination, though that's who had to ultimately sign and stand behind the denial, and (ii) more importantly, it appears that the denial was actually appealed and NIST won the appeal on a motion for summary judgement, which is a standard under the FOIA filer's argument was viewed in the most favorable possible light. This means a federal court actually considered whether there was a basis for NIST's determination and we don't have to take the DoT's word for it.

And we actually even have a final decision by that court on this matter that is public record. You can find it here. Relevant excerpt:

Second, NIST has provided ample support for its contention that its decision to withhold 68,500 data files involved a straightforward application of FOIA Exemption 3, which permits an agency to withhold information "specifically exempted from disclosure by statute . . . if that statute . . . refers to particular types of matters to be withheld." 5 U.S.C. § 552(b)(3)(A)(ii). Of particular relevance here, the NCSTA expressly precludes NIST from "publicly releas[ing] any information it receives in the course of an investigation . . . if the Director finds that the disclosure of that information might jeopardize public safety." 15 U.S.C. § 7306(d). In conformity with this provision, the Director of NIST made an express finding that the public disclosure of certain types of information pertaining to the architectural and engineering modeling of the collapse of the WTC 7 building might jeopardize public safety — generally speaking, detailed connection models, connection material properties, and break element strips that had been validated against actual events. Fletcher Decl. ¶¶ 17-18, 22 Ex. 4. Reduced to layman's terms, the difference between the information that was released and the information that was withheld is that the released data files contain structural models based on information generally available to building designers and engineers, whereas the withheld data files contain information that could be used to predict the collapse of a building and, if made available to a person with the appropriate level of expertise, would provide instruction to individuals wanting to learn how to simulate building collapses and how to most effectively destroy large buildings. Id. ¶ 22. As contemplated by the statutory scheme created by Congress, the Director of NIST brought his expertise to bear on the subject and determined that the public disclosure of such information "might jeopardize public safety," 15 U.S.C. § 7306(d), and should be withheld. This explanation for non-disclosure is sufficiently "logical" or "plausible" to satisfy NIST's burden of justifying its withholdings, Larson v. Dep't of State, 565 F.3d 857, 862 (D.C. Cir. 2009), and

NIST has, moreover, explained in a "relatively detailed" manner why the exemption is relevant in this context and has appropriately correlated the exemption with the pertinent records, Judicial Watch, Inc. v. Food Drug Admin., 449 F.3d 141, 145 (D.C. Cir. 2006). In short, NIST has provided an adequate explanation of, and justification for, its withholding decisions.

So a federal court, looking closely at the denial in the manner most favorable to the FOIA filer, found that the basis provided by NIST for the denial held up. But that won't stop you from baselessly speculating otherwise.
 
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Thomas B

Active Member
How does releasing the data to the general public achieve that benefit?
Making it available to scientists either in a publicly available repository (as is done in other "open science" projects) [edit: or to anyone who asked] would by default also make it available to the public.
If you can find even one actual structural engineer who works on real world high rise building projects who thinks they need that data in order to improve their designs (and who have directly requested it subject to confidentiality obligations and been denied)...
If this is the current practice, i.e., if data is released only to people who can explain what they need it for and sign some sort of NDA related to it, then it is obvioulsy impededing science with bureauracy. Also, it's unclear how any research using this data might be published if it is released with such restrictions.

I'm not aware of any research that has been done using NIST's data and Hulsey was, as far as I know, denied it, though his interest was ostensibly scientific.

You are straining to conjure up a motive for the denial that fits your preconceived notions when there is zero evidence for one.
There are quite a few cases of researchers providing a variety of implausible reasons for not releasing their data when the real reason (as is eventually discovered) is that they made serious errors in their analysis or even outright fabricated the data. I didn't say I know that's what happened here. I said not releasing data (especially when the arguments don't really make sense) is a "red flag".
 
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benthamitemetric

Senior Member
Making it available to scientists either in a publicly available repository (as is done in other "open science" projects) would by default also make it available to the public.

If this is the current practice, i.e., if data is released only to people who can explain what they need it for and sign some sort of NDA related to it, then it is obvioulsy impededing science with bureauracy. Also, it's unclear how any research using this data might be published if it is released with such restrictions.

I'm not aware of any research that has been done using NIST's data and Hulsey was, as far as I know, denied it, though his interest was ostensibly scientific.


There are quite a few cases of researchers providing a variety of implausible reasons for not releasing their data when the real reason (as is eventually discovered) is that they made serious errors in their analysis or even outright fabricated the data. I didn't say I know that's what happened here. I said not releasing data (especially when the arguments don't really make sense) is a "red flag".
This was not an open science project. This was a governmental investigation. In the US, citizens have a right to the public release of data from federal agencies subject to statutory FOIA requirements. One of the statutory exceptions to that right is if the release of that data would threaten public safety. Here, a federal court agreed with NIST's assessment that the release would threaten public safety. This does not mean that others could not access the data outside of the FOIA framework; this decision was based solely within the context of a FOIA request. You cannot even acknowledge that risk and instead handwave it away to focus only on bland platitudes re potential benefits that are not supported by any public statement from any actual structural engineer who designs high rise buildings and to whom, if anyone, such benefits of this data would accrue (i.e., there is no known outstanding need for the data from experts with good intentions but, in any case, you imagine you know better than them what they need). I've also never seen any evidence that Hulsey ever requested the data or communicated with the NIST authors and his report does not say that he did, but maybe you know otherwise.
Maybe we can get @Landru to move this discussion about FOIA to another thread? It started with @Henkka 's comment #223.
There is nothing more to post about as your argument is "nuh-uh, I just don't believe NIST."
 
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Mendel

Senior Member.
Terrorists are generally content to blow stuff up, shoot people, drive cars into crowds etc. They're not doing advanced engineering analysis to cause the total collapse of buildings.
Ziad Jarrah studied aerospace engineering in college. Marwan al-Shehhi studied shipbuilding in college. It wouldn't surprise me if they had access to finite elements analysis software. The 9/11 terrorists spent many months and many thousands of dollars preparing for this attack.
It seems to me that your assertions are wishful thinking ("argument from incredulity"), and that some terrorists would totally do advanced engineering analysis if it helped the jihad.

I would definitely like to see a simulation that "looked like" the real event. I don't think that's too much to ask.
Civil engineering software that is useful and validated is typically used to analyse stresses in (mostly) intact structures. Once a structure is starting to fail, the question that caused the simulation to be run is typically answered. Therefore, commercial civil engineering analysis packages are not designed to simulate realistic collapse events beyond the "it's broken" point.

To ask someone to do something for which no software exists to it with, that is indeed too much to ask. (Ask Kai Kostack how easy it is to make one—he has been trying for years and not succeeded yet.)

Note that a visualization (looks like the real thing) and a simulation (works like the real thing) are different!
 

Henkka

Active Member
There is nothing more to post about as your argument is "nuh-uh, I just don't believe NIST."
Well, isn't your argument "The Director of NIST said so, and a court agreed"?

I've no clue what arguments, if any, were presented at this court hearing. It seems we should just take it on authority that a lack of transparency is for our own good. I don't think that's very "skeptical". We shouldn't just take things on authority, and I haven't really heard a convincing argument for this "public safety" thing. I don't think there is even a chance of one in a million of some terrorist using these simulation files to develop plans to destroy some other building.

Especially when you consider the cause of the WTC 7 collapse... It was a fire. So terrorists are going to learn how to collapse skyscrapers through arson, provided they first disable the sprinklers and somehow ensure there's no firefighting response for at least 7 hours? It is absurd.
 

benthamitemetric

Senior Member
Well, isn't your argument "The Director of NIST said so, and a court agreed"?

I've no clue what arguments, if any, were presented at this court hearing. It seems we should just take it on authority that a lack of transparency is for our own good. I don't think that's very "skeptical". We shouldn't just take things on authority, and I haven't really heard a convincing argument for this "public safety" thing. I don't think there is even a chance of one in a million of some terrorist using these simulation files to develop plans to destroy some other building.

Especially when you consider the cause of the WTC 7 collapse... It was a fire. So terrorists are going to learn how to collapse skyscrapers through arson, provided they first disable the sprinklers and somehow ensure there's no firefighting response for at least 7 hours? It is absurd.

On one side of the scales we have:
  • The Director of NIST made the statutory determination of a threat to public safety.
  • The DoT's Office of General Counsel signed off on the determination.
  • NIST submitted multiple sworn declarations by NIST employees under penalty of perjury (as referenced in the court's opinion) supporting the determination to federal court.
  • A federal court reviewed the determination in the light most favorable to the FOIA filer and agreed with NIST.
  • The determination on its face does actually make logical sense (hence I reached the same conclusion as the court without even knowing of the court decision).
  • The Journal of Structural Engineering peer reviewed NIST's chief findings for over a year before publishing them, showing that actual professionals could get from NIST the data they need to evaluate NIST's work.
  • None of the data was necessary for any of the many professionals who completed subsequent investigations in the Aegis Insurance litigations to draw their own conclusions.
  • The data was not necessary for Hulsey to draw his (farcical) conclusion.
  • There is no known public statement by any high rise building experts saying that there is a need for this data to be made available to the public.
  • No evidence that there was an ulterior motive for the denial.
On the other side of the scales we have:
  • The general presumption in favor of the freedom of information.
I actually give a lot of weight to the presumption in favor of the freedom of information, but I think NIST's reasoning remains plausible and, balancing the scales above, is likely right, if risk averse. And while arguments from authority are flawed, I'm not making one, and, in any case, they are far better than arguments from pure imagination and bias-motivated incredulity.

Especially when you consider the cause of the WTC 7 collapse... It was a fire. So terrorists are going to learn how to collapse skyscrapers through arson, provided they first disable the sprinklers and somehow ensure there's no firefighting response for at least 7 hours? It is absurd.

This is highly disingenuous as NIST's concern was with design vulnerabilities that could be exploited by any destructive means.
 
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Henkka

Active Member
And while arguments from authority are flawed, I'm not making one, and, in any case, they are far better than arguments from pure imagination and bias-motivated incredulity.
Well, would you agree it is still largely an argument from authority, considering the authorities in question have not explicitly explained their reasoning for how the files could be used to develop plans to destroy other buildings? Maybe there is a really good argument for it, but I just haven't heard one. Like we're not talking about research that could be used as instructions to building a dirty bomb in your garage. It's simulation files of how fires destroyed one particular building.
This is highly disingenuous as NIST's concern was with a design vulnerabilities that could be exploited by any destructive means.
So do you think the files could be used to reveal a kind of "Achilles' heel" in another building that could be taken out with a bomb or such?
 

Thomas B

Active Member
So do you think the files could be used to reveal a kind of "Achilles' heel" in another building that could be taken out with a bomb or such?
The disturbing possibility is that NIST has in fact discovered a design flaw (and one they think may have been reproduced in many other buildings) that makes skyscrapers vulnerable to total collapse from damage far less than what demolition crews intentionally (and with great difficulty) bring about.

Of course, this isn't really news because NIST has been quite open that a single bomb placed on column 79 (and powerful enough only to cause that one column to fail) would have had the same result as what happened on 9/11.

It's strange to think that NIST is concealling a way to do this from potential terrorists that would be easier than planting one bomb. In fact, I agree with Henkka that this sounds absurd.

I think it is much more likely that NIST fudged the data to come up with a model that generated a result that was more or less in line with the outcome. Without such fudging they would have had to admit that they couldn't explain what happened to WTC7 and that would leave the door open to conspiracy theories. I think part of their implicit remit was to put those theories to bed.

They did a pretty good job. The theories have been put more or less to bed, at least in the public sphere.

"The reason for the collapse of World Trade Center 7 is no longer a mystery," said Dr. Shyam Sunder when the report was published. So it at least had been a mystery. Maybe it was decided somewhere in the system that leaving this mystery publicly unsolved was intolerable. People have to trust that the buidlings they work in every day will remain standing.

It would not be the first time that an official report has offered public assurances about things that could not be scientifically demonstrated, right? We don't believe that such things never happen, right? And, surely, given the need to both assure the public of the safefy of skyscrapers and the need to dismiss conspiracy theories (which were quite popular in 2008, you'll recall) this was certainly a situation that could have gotten a whitewash.

I personally think that's more plausible than NIST's explanation. But I want to emphasize that to say that I suspect NIST doesn't quite know why WTC7 collapsed (and doesn't want to admit it) is not to say that I think it was demolished by the US gov't. That's absurd too.
 

Henkka

Active Member
Of course, this isn't really news because NIST has been quite open that a single bomb placed on column 79 (and powerful enough only to cause that one column to fail) would have had the same result as what happened on 9/11.

It's strange to think that NIST is concealling a way to do this from potential terrorists that would be easier than planting one bomb. In fact, I agree with Henkka that this sounds absurd.
Yeah, this is already public information in the report put out by NIST. If an aspiring terrorist wants to understand the collapse of WTC 7 so he can replicate it on another building, he can already read all about it in exhaustive detail in the NIST report. NIST's position seems to be that reading the report would not provide enough information to develop plans to destroy another building, but those simulation files would do the trick. But what could possibly be in those files to make the difference? We're talking about extremely minute details of a collapse that NIST purports to have already explained in their report. Whether through arson or by placing a bomb on a key column, a terrorist already has plenty of information to attempt replicating the collapse if they wanted to do so.
 

benthamitemetric

Senior Member
Well, would you agree it is still largely an argument from authority, considering the authorities in question have not explicitly explained their reasoning for how the files could be used to develop plans to destroy other buildings?

No, I don't think they left much to the imagination at all. And, if you couldn't figure it out from what was said in the denial letter, the court opinion I linked above makes it about as clear as possible:

"[T]he difference between the information that was released and the information that was withheld is that the released data files contain structural models based on information generally available to building designers and engineers, whereas the withheld data files contain information that could be used to predict the collapse of a building and, if made available to a person with the appropriate level of expertise, would provide instruction to individuals wanting to learn how to simulate building collapses and how to most effectively destroy large building."

In other words, they didn't want to give potential terrorists a set of ready-made analytic tools into which they could import other building designs and probe for weaknesses. This strikes me as entirely reasonable and people who are already expert in these fields don't need NIST's tools to evaluate their claims or to conduct similar analyses because they already have the expertise and tools to do it themselves. And, as Hulsey showed us, it's not easy for nonexperts to do it correctly, even with a substantial budget and tangential experience.

So do you think the files could be used to reveal a kind of "Achilles' heel" in another building that could be taken out with a bomb or such?
Yes, obviously; that's the whole point.
 
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Abdullah

Active Member
The argument about withheld data will probably just bloat this thread. Do let's move forward. How did column buckling lead to freefall?

1. They buckled across multiple storeys(NIST)

2. They didn't buckle(FEMA)
 

econ41

Senior Member
The argument about withheld data will probably just bloat this thread. Do let's move forward. How did column buckling lead to freefall?

1. They buckled across multiple storeys(NIST)

2. They didn't buckle(FEMA)
I agree "let's move forward". So why not stop going round in circles and pursuing irrelevant discussion.

More specifically STOP "RE-conflating" or "RE-generalising" those matters where I or other members have alrew3ady made the actual issue more specific and removed ambiguity.

So the starting premises are:
1) The TOPIC is labelled: "How Buckling Led to "Free Fall" acceleration for part of WTC7's Collapse;
2) It refers to the observed fall of one face of WTC7;
3) ... through a height of approximately 8 storeys
4) ...and with near Free Fall Acceleration;

ALL four of those are the starting premises for this discussion. Anyone who wants to deny them or discuss some other topic is Off Topic. They should stop derailing this thread. Either start their own thread, restart an old thread or show how the new topic is legitimately related to arguing the topic of this thread.

The so-called "argument" about withheld data is offtopic. So I won't waste time rebutting the nonsense that has been posted.

The fact that the perimeter shell for WTC7 fell at near Free Fall ACCELERATION is trivially answered by the assertion: "Something must have removed its support." (and what should be equally obvious NEITHER "NIST withheld data" NOR "Some of the core was still attached" NOR - even sillier - "There was no perimeter shell" have any relevance to explaining how the support was removed.

SO the question for discussion or debate becomes "What removed the support from under the bits of WTC7 that fell ~8 storeys at near free-fall"? (And a possible secondary question for those who are not so accomplished at physics: ""Why did removal of support cause 99% (or 85%) (or "nearly:") "G").

The OP presumes "buckling". Some members (@Jeffrey Orling and @econ41 -- possibly more.) have identified that transfer truss failure ["TTF"] may be a factor. I have asserted that TTF has not been eliminated and therefore must still be considered.

So there are three plausible methods of removing support from under the subject perimeter facades of WTC7:
(a) Buckling alone;
(b) Some mix of contributions from Buckling of columns and Transfer Truss failure; OR
(c) CD.

So that is the topic. Does anyone disagree? If so provide both the alternate definition for on-topic discussion and reasons for disagreement.
 

econ41

Senior Member
I am creating a new thread for TTF
Why. It is proposed as one of the causes of: "[What] Led to "Free Fall" acceleration for part of WTC7's Collapse." If there are two contributions to causing the free fall how can they be sensibly discussed in separate threads?
 

econ41

Senior Member
@econ41 did you just disagree with yourself lol
No. Please read what I said. I'm suggesting we move the discussion forward. I thought you agreed.

There can be no valid reasoned discussion of the part that buckling played in causing the observed FFA collapse if the discussion only considers that single factor. OR "begs the question" by presuming it is the only factor in play.
 

Mendel

Senior Member.
I don't think there is even a chance of one in a million of some terrorist using these simulation files to develop plans to destroy some other building.
"Argument by incredulity", see my previous post. At least 2 actual 9/11 hijackers probably had enough technical knowledge to do this.

The actual issue is that the choices NIST made in "programming" the model align with reality, so if you model a similar building the same way, you know your model is probably going to predict the collapse correctly if you identify a vulnerability.

In other words, if you are a terrorist aiming to bring down a steel frame building, model it like NIST modeled WTC7 and then play around with the model to find the easiest way to destroy it.

However, if you don't have access to the NIST model, you need to guess at some of the settings they made, and guess at some of the decisions made on how to model certain properties of the building, and then you can no longer be sure that your model reflects reality: something that collapses the model in the simulation might not work in reality, and your terror attack could fail.

This uncertainty is preserved by not publishing the NIST model in full.
Especially when you consider the cause of the WTC 7 collapse... It was a fire. So terrorists are going to learn how to collapse skyscrapers through arson, provided they first disable the sprinklers and somehow ensure there's no firefighting response for at least 7 hours? It is absurd.
It's absurd to suggest that terrorists would start multiple big fires in a building (and disable the sprinkler system and water mains in the ares to thwart fire fighting efforts) to exploit a structural vulnerability, rather than to attack that vulnerability directly.

I am creating a new thread for TTF
This is like discussing "there was a UFO sighted over London" and then suggesting to create a separate thread for "sighting was possibly a balloon" because it's not about aliens.
 

Mendel

Senior Member.
It would not be the first time that an official report has offered public assurances about things that could not be scientifically demonstrated, right?
Could you please cite that precedent?

To apply here, that "public assurance" would need to include the statement that a "scientific"/engineering investigation did take place, and was documented similarly to how NIST documented theirs.

The NTSB regularly conducts engineering investigations into accidents and sometimes bridge collapses; they typically document them with less detail than NIST documented theirs; and as far as I'm aware, they've not been proven wrong or misleading.
It's simulation files of how fires destroyed one particular building.
The fires were simulated separately (i.e. using different software) from the structural analysis of the stability of the building, i.e. one simulation was about the fire, and the results were fed into another simulation that was about the destruction.
 

Abdullah

Active Member
This is like discussing "there was a UFO sighted over London" and then suggesting to create a separate thread for "sighting was possibly a balloon"
This thread is more limited in scope. The thread title is

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

 

Henkka

Active Member
In other words, if you are a terrorist aiming to bring down a steel frame building, model it like NIST modeled WTC7 and then play around with the model to find the easiest way to destroy it.
Should we be concerned with terrorists going to engineering school to learn how to make such simulations on their own, without NIST's input? If you want to learn how to bring down buildings, you don't have to wait around for NIST to release some ancient files... Get an engineering degree, and then maybe a job at CDI.

Besides, I think it's accepted that you generally can't bring down a steel skyscraper by blowing up one column, and what happened with WTC 7 was an extreme anomaly. So if you were to construct a similar model of the Empire State Building, I find it implausible that you could fiddle around with it until you found some "Achilles' heel" type vulnerability.

You could call it an argument from incredulity, but that is kind of all I'm saying, I am incredulous of the reasoning given by NIST. I find it so farfetched that I'm more inclined to believe they don't feel very confident in their results. I also think that if someone were to render more frames of this simulation:

Jun-07-2022 09-17-36.gif

It would probably not show the simulated building going smoothly straight down at 99% of g as observed. That would be why they cut it there. If they were able to produce a simulation that replicated the collapse, they would be proudly showing it off, rather than cutting it like that.
 

Thomas B

Active Member
Could you please cite that precedent?
Off the top of my head, the best example is probably the Rogers Commission, which looked into the Challenger disaster. Without Feynman's dissent, it would have been essentially a whitewash. (In fact, if he hadn't been on the commission, it's likely the report would have been even less truthful.)
Feynman felt that the Commission's conclusions misrepresented its findings, and he could not in good conscience recommend that such a deeply flawed organization as NASA should continue without a suspension of operations and a major overhaul.
Content from External Source
https://en.wikipedia.org/wiki/Rogers_Commission_Report

But I don't quite understand your pushback on this. You don't think the government ever uses official investigations to sweep problems under the rug and gloss over controversies that might cause public anxiety or civil strife?
 
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Mendel

Senior Member.
Should we be concerned with terrorists going to engineering school to learn how to make such simulations on their own, without NIST's input?
If you don't have access to the NIST model, you need to guess at some of the settings they made, and guess at some of the decisions made on how to model certain properties of the building, and then you can no longer be sure that your model reflects reality: something that collapses the model in the simulation might not work in reality, and your terror attack could fail.

Typically, this kind of software is designed to answer the question "is this building safe" correctly in the sense that no false positives occur (no unsafe building deemed safe), which typically means false negatives are more common (building deemed unsafe that would be safe). So if you are running the model with the question, "is this unsafe", you can't use a textbook approach and have confidence in the result.

If you want to learn how to bring down buildings, you don't have to wait around for NIST to release some ancient files... Get an engineering degree, and then maybe a job at CDI.
Or you could park a truck with a fertilizer bomb in front of the building... though that kind of approach failed to bring the WTC down in 1993. Now if they'd had a working model in 1993, maybe they could've placed the bomb differently and succeeded? or predicted the building wouldn't come down and made the attack bigger?

Besides, I think it's accepted that you generally can't bring down a steel skyscraper by blowing up one column, and what happened with WTC 7 was an extreme anomaly. So if you were to construct a similar model of the Empire State Building, I find it implausible that you could fiddle around with it until you found some "Achilles' heel" type vulnerability.
So what would you pay to find out exactly what it taked to bring the Empire State Building down, if you were a terrorist? If you can coordinate 4 airliner hijackings on the same morning, maybe you don't need an Achilles heel, just something that works.

I also think that if someone were to render more frames of this simulation:
Jun-07-2022 09-17-36.gif
It would probably not show the simulated building going smoothly straight down at 99% of g as observed. That would be why they cut it there. If they were able to produce a simulation that replicated the collapse, they would be proudly showing it off, rather than cutting it like that.
yes, because the software is not designed to simulate a collapse realistically. The makers spent effort on ensuring that the answer to "does it break" errs on the side of caution if at all; the question of "what happens after it breaks" is not part of the objective, and would also require different algorithms to track the rubble and what it impacts. These loads are abstracted in a "spherical cow" fashion for the analysis of working buildings, and they wouldn't be simulated correctly in a failing building.
Article:
Milk production at a dairy farm was low, so the farmer wrote to the local university, asking for help from academia. A multidisciplinary team of professors was assembled, headed by a theoretical physicist, and two weeks of intensive on-site investigation took place. The scholars then returned to the university, notebooks crammed with data, where the task of writing the report was left to the team leader. Shortly thereafter the physicist returned to the farm, saying to the farmer, "I have the solution, but it works only in the case of spherical cows in a vacuum."
 

Mendel

Senior Member.
Off the top of my head, the best example is probably the Rogers Commission, which looked into the Challenger disaster. Without Feynman's dissent, it would have been essentially a whitewash. (In fact, if he hadn't been on the commission, it's likely the report would have been even less truthful.)
But Feynman was the scientist on this commission, and he talked to the engineers at NASA, and thus the report was not a whitewash, and not the precedent that I asked for.

Also, the Rogers Commission was a political commission (Presidential, even, so you had the "supreme boss" of NASA order an investigation about NASA); in 9/11 terms, the closest comparable body might be the 9/11 commission (and I'd look very carefully for bias in its findings about the federal response to the attack), but NIST is an engineering body and not a political committee.

But I don't quite understand your pushback on this. You don't think the government ever uses official investigations to sweep problems under the rug and gloss over controversies that might cause public anxiety or civil strife?
You're overgeneralizing. (And off the top of my head, I can't think of an example.)

What we have here is not a political investigation, and not even a legal investigation, it's an engineering investigation that was sufficiently detailed to allow for meaningful peer review.

If argument by incredulity is acceptable to you, let me be incredulous that such an investigation has ever been subverted. It's your claim anyway, so it's your onus to support it.

Or bring a single shred of evidence that shows NIST acted in bad faith in their 9/11 analyses.
 
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econ41

Senior Member
You're overgeneralizing. (And off the top of my head, I can't think of an example.)
There is probably a fancy Latin name for the trick he is attempting but I don't know it.

What he is attempting to fool us with is that he makes a specific complaint about a specific action or event"A". Generalises it to a complaint about the set "alphabet". Finds that there are other cases (or is another case) in the set for which the complaint is valid. Say "Q". And concludes "Because true case "Q" exists, case "A" must also be true.

Utter nonsense whether or not there is a Latin name for the logical nonsense trickery. ;)
 

Henkka

Active Member
Or you could park a truck with a fertilizer bomb in front of the building... though that kind of approach failed to bring the WTC down in 1993. Now if they'd had a working model in 1993, maybe they could've placed the bomb differently and succeeded? or predicted the building wouldn't come down and made the attack bigger?
Everyone including terrorists already knows what would be the most sure way of bringing down the Empire State Building... Charges detonated simultaneously on most or all of the main columns, ie a controlled demolition. But terrorists don't have the capability to do something like that, at most they can place one or two crude bombs in the vicinity of those columns. But it's hard to actually destroy a column with a simple bomb, since the energy from a bomb blast goes in all directions, rather than being focused on the column. You would need an extremely powerful bomb, which conversely becomes much harder to somehow sneak into the building.

So the idea is that with information from the NIST files, terrorists could somehow figure out which column in the Empire State Building they need to place a huge bomb next to, and then that might bring down the entire building. And they specifically need the NIST WTC 7 simulation files to accomplish this, simply studying structural engineering or reading the report won't be enough. As I've been saying, I think this is absurd, and there is not even one in a million chance of this sequence of events taking place if they released those files.
If you don't have access to the NIST model, you need to guess at some of the settings they made, and guess at some of the decisions made on how to model certain properties of the building, and then you can no longer be sure that your model reflects reality: something that collapses the model in the simulation might not work in reality, and your terror attack could fail.
yes, because the software is not designed to simulate a collapse realistically.
This seems contradictory?

If the simulation does not match the real collapse, how can you be sure the simulation explains why the collapse occurred? Just because you can get a virtual replica of WTC 7 to collapse one way inside a computer, that doesn't mean that's what actually happened on September 11th around 5:20PM.
 

econ41

Senior Member
I'm siding with @Henkka on the question of whether NIST/DoT's reasoning is absurd. You suggested that there would great (if remote) harm and no benefit to releasing the data. I'm saying there are some obvious benefits.
So why are the two of you determined to push the discussion off-topic? And @Abdullah is even creating a separate thread to fragment and prevent reasoned discussion?.

The OP theme is simple: "How Buckling Led to "Free Fall" acceleration for part of WTC7's Collapse."

Which is a simple technical issue provided we dispose of the unjustified implications that buckling did in fact lead to the observed free-fall and that buckling was the only cause.

The answer should actually be quite trivial. "If you remove the support from under something it will fall down" THEN the challenge is to explain how the support was removed. And "buckling" is a likely contender but is it the only causal process? << And THAT is the debate - not the derail into conspiracy theorists trying to justify their distrust of NIST.
 

Jeffrey Orling

Senior Member
The proximate cause was the failure of the MG27 girders which were cantilevers supporting the north side of the moment frame and curtain wall on the cantilevered ends. The MG27s lost support at the core side and likely with the collapse of transfer truss 1SanderO's_WTC 7 TTF_Cartoon_213.png
 

Henkka

Active Member
I agree this is somewhat veering off-topic, but I don't want to not reply to something I find interesting to talk about just because it's technically off-topic. And it is still related... The thread is about NIST claiming that buckling explains why the roofline of the building appeared to be in free fall acceleration for about 2.25 seconds. They base this on their simulations, stating:
This is consistent with the structural analysis model, which showed the exterior columns buckling and losing their capacity to support the loads from the structure above.
My question was, how do we know the simulations to be accurate? As with anything, trust should be proportional to transparency. And my trust that NIST got it right would be greatly increased if all their simulation files were publicly released. Because they're not, we depend on their say-so.
 
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