OOS Collapse Propagation Model

[Myriad]

This depends perhaps a bit on how you picture a "block" - as "rigid" perhaps, or, as you do, as "mutually unconnected". This may be false in the WTC case IF both "blocks" pierce through the rubble layer between them and thus mingle.
The BV-model, it seems to me (but remember: I haven't read it ), pictured a top block "surfing" on the rubble layer; the rubble is what crushed the "lower block" in Bazant's model, and the "upper block" rides on it safely. But what if columns don't cooperate and refuse to be crushed by the rubble layer, and the blocks poke into each other?

There's also some confusion about the import of the descriptor "rigid." There's "Superman could pick it up by one corner and fly away with it" rigid (which real buildings or large portions thereof never are), and there's "able to redirect loads to the remaining available load paths without major deformation" rigid (which the upper blocks were, until they weren't).

Once collapse began, the import of the "rigidity" of the remaining "upper block" was that all of the momentum of the upper block was potentially available to bear (even if only momentarily) upon whatever obstacles below offered resistance.

 

[ozeco41]

The JREF/ISF debunking crowd certainly doesn't help with its tough-on-truthers style,...

Well said - and you are putting it mildly. This thread possibly the worst example.

but that cannot be the reason you insist your mission is that of the anthropologist, recording "debunking subculture memes" and insisting you are merely documenting things that to any casual observer are so forlorn, the real motives emerge between the lines despite the pretense.

Frankly I find that to be the real puzzle - why your motivation is given such a pass. The bottom line is that a few folks hurt your feelings, didn't they? Someone owes you an apology, don't they? Probably Ryan Mackey does, doesn't he? It seems the list of folks that ought to address your grievances is the same you constantly cite under the guise of some "meme" they allegedly got wrong, "memes" so trivial they cannot possibly warrant the deep anthropological mission of debunking-subculture-meme-documenter you pretend to be on.

I'm unsure how serious you are Bravin. I suggest that the issue is more basic than - deeper than - personal "hurt". Best seen IMO as one of a group of genuinely concerned people who wanted to understand 9/11 matters and started from what would now be called "truther" positions. (It was before the word was in use and before the current simple two way polarisation.) Some of those people did a lot of research and as a consequence some moved away from their "truther" starting points.

I propose an M_T apology thread. I think it will help everyone.

It would need to be two way - mutual.

Check the thread history - I've persisted with a 4+ year losing battle to get the three groups of issues separated:
1) Technical - where the fact that M_T is right on some key issues is culturally unacceptable on the forum. And the need to insist M_T is wrong but we are right causes obvious conflicts when both are saying the same thing - and dare not admit it. Hence the animosity and game playing directed at me because I put the issues a lot more explicitly than M_T;
2) The behavioural aspects which are loosely labelled "memes" - which reveal M_T's confusion of objectives - he leads with technical issues but asserts that his aim is "anthropological". My assessments "Wrong topic for this forum" and "Probably not suitable for forum discussion on 9/11 or CT forums" (It puts the foxes in charge of the chicken coop - there is a better metaphor which I cannot remember - refereeing your own fight or similar )

THEN

3) Issues of M_T's "style" which can be seen as "giving as good as he gets" if you read the first page or two of the thread and ask "who started the insulting conduct"

 

[ozeco41]

I don't see why it's such a thoughtcrime to refer to the 'upper block'.

It is probably not an issue of current concern. It was at the time of Heiwa et al. I used to avoid it but it is convenient and for the last couple of years I've stopped avoiding it.

After collapse initiation it's more or less axiomatic that there were two, mutually unconnected, sections of the original structure, one above the other, and the word "block" to refer to them is as good as any other.

Except that the "After collapse initiation..." period that the "block" existed as an integral bit of structure was very brief-

- by the time it started falling bodily the destruction by crush down AND concurrent crush up was under way.

The "Top Block" did not ride the collapse dowm to ground level THEN crush up - even tho' the energetics maths fro a 1D homogeneous model says it would for such an abstracted model.

 

[Bravin Neff]

Actually, the history behind all this is rather amusing. It's all rooted in, believe it or not, the Truth Movement's reaction to NIST NCSTAR...

Great history, Myriad. Thank you.

 

[ozeco41]

Well, while we're waiting, we could discuss your reasoning for wanting a column-spacing factor in the model. Shouldn't the total floor shear capacity be the total floor load plus a factor of safety, regardless of column spacing? Or, we could discuss whether or not the perimeter wall would have more of a "funnel" effect with wider column spacing. Or, whether any such "funnel" would make much difference in a 200-foot-wide building.

OK let's take the first step - remember that I said:

It forces me to think seriously.

....And I think it will be exploratory thinking

.... it is an issue I've been taking for granted .

My starting premises are the two extremes of a vector range of possibilities:
1) At one extreme progression collapses can be legitimately explained by buckling or column crushing energetics as per the Bazant "Limit Case" and the valid extension of those into the generic Model that Bazant was pursuing in BV. Plus any other real event collapse where column buckling/"crushing" is the primary factor. (And this bit of disclaimer to show I'm not overlooking it - and other factors are a lower order of magnitude).

2) At the other extreme the WTC Twin Towers collapses progression stages were dominated by floor joist shear failure energetics. NOT column buckling/crushing. The same would apply to any other similar collapse - excuse the circularity i.e. any collapse which like WTC did not crush/buckle columns. (and other factors are a lower order of magnitude).

I think we are agreed those two as premises. If not please ask for more clarification/justification.

Now from here my reasoning goes in two stages. In Stage #1 I'm seeking to establish agreed premises for debate/explanation of your topic "we could discuss your reasoning for wanting a column-spacing factor in the model."


Here goes - Stage #1: The two scenarios in those two premises set the extremes of what I will regard for discussion purposes as a single vector. (Yes real life will be more complicated...save for later) And I'll restate it complete with the two almost circular arguments.

A) At the extreme where column crushing/buckling dominates THEN column crushing energetics are appropriate. << That also should be agreed - say if not so. And it is the premise under much of Bazant's work.

B) At the other extreme - where WTC Twins are two real event examples - floor joist shearing dominates (should be agreed) THEN joist shearing energetics are appropriate. << Not sure we are agreed on that aspect yet.

AND -in my earlier posts I suggested that the equations from Bazant's series of papers could be prima facie valid for application to WTC real event IF joist shearing energetics factors were substituted in the maths replacing column crush energetics. That is the point I first made either 2010 or 2008 and have never followed up myself and I'm not aware of anyone other than you go close to suggesting it or similar. Are you comfortable with that first step of pushing forward with the logic?

At this stage I am bypassing the issue down the other track - whether of not column crush energetics are a close enough approximation for a Twin Towers scenario. And I suggest the joist shear energetics would naturally be a better approximation.

Those are the two extremes. If we can agree those basics of the range of options - or we discuss them further to reach agreement - modifying if necessary - in a subsequent post I can then address the topic that you raised:

That topic being: "we could discuss your reasoning for wanting a column-spacing factor in the model. Because my reasoning is intended to bridge the gap between the two extremes.

 

[Major_Tom]

There's also some confusion about the import of the descriptor "rigid." There's "Superman could pick it up by one corner and fly away with it" rigid (which real buildings or large portions thereof never are), and there's "able to redirect loads to the remaining available load paths without major deformation" rigid (which the upper blocks were, until they weren't).

Once collapse began, the import of the "rigidity" of the remaining "upper block" was that all of the momentum of the upper block was potentially available to bear (even if only momentarily) upon whatever obstacles below offered resistance.

All you would have to do is refer to the papers you have been defending to read, or even quote, what Bazant writes on this subject to find out what he meant.

Have you read BV and BL? Judging by your posting history, it seems like you haven't. Is it true that you haven't read those papers?

 

[beachnut]

All you would have to do is refer to the papers you have been defending to read, or even quote, what Bazant writes on this subject to find out what he meant.

Have you read BV and BL? Judging by your posting history, it seems like you haven't. Is it true that you haven't read those papers?

More questions; where are the "book" answers? What do you think you are, a professor like paper chase? Your posts are evidence of a lack of understanding engineering models.
Is it true you still believe in CD? Or did you drop the fantasy of CD, and the nonsense the gravity collapse is an illusion? If you did drop the CD fantasy; why, when and what made you wake up to reality?


Did you comment on this yet?

This failure mode has been discussed for a very large period of time and it just a rehash of what everyone who wasn't delusional already knew. Bazant and Zhou talk about the column failure mode as the limit state as, "nlikely though such a distribution may be, it is nevertheless the most optimistic hypothesis to make because the resistance of the building to the impact is, for such a distribution, the highest."

Bazant and Verdue states that, "The kinetic energy of the top part of the tower impacting the floor below was found to be about 8.4 larger than the elastic energy absorption capability of the underlying story," and the the purpose of the Bazant and Verdue paper is not to describe the WTC collapse, but rather to create "a theory describing the progressive collapse dynamics" as this would be "very useful for other purposes, especially for
learning from demolitions".

Why come up with this new term "open office space flooring"? It's not real. You're literally the only person to use that particular phrase. You're not going to win any bonus points by coming up with new jargon. It's just going to make you look like you don't know what you're talking about. Which leads us back to the purpose of this post: you don't know what you're talking about. You're not even capable of reading for understanding what you're supposedly debunking.

Let me spell it out for you one more time. When a column develops plastic hinges and buckles it absorbs a very large amount of energy. It absorbs orders of magnitudes more than a simple shear connection failing, or a truss web, or a connection from the perimeter column to the diaphragm. If there is not enough available energy absorption in the columns then there is no possible way that the building could resist the collapse. Bazant and Zhou shows this very clearly. If you want to argue otherwise, fine. But first you must show which elements have the necessary capacity to resist the collapse.

Why can't 911 truth understand engineering models?

 

[Major_Tom]

AND -in my earlier posts I suggested that the equations from Bazant's series of papers could be prima facie valid for application to WTC real event IF joist shearing energetics factors were substituted in the maths replacing column crush energetics.

The only way you can verify this is to understand the step by step derivation of BV equation 12 (the crush down differential equation). You then look at each step to see if joist shearing is consistent with each step.

Don't use a differential equation in specific situations that you do not know how to derive, or you will have no idea whether it can be applied in that specific case. Otherwise you are just guessing or believing the claim of another person which you cannot verify.

 

[Major_Tom]

That's where Bazant and Zhou's original progressive collapse paper, "BZ," came in. As a limiting case ("best case for collapse arresting") model, it shows that the structure cannot absorb the energy necessary to arrest collapse, and so the progressive collapse proceeds to the ground. All the details of that analysis, such upper and lower "blocks" and "crush-down" and "crush-up," are artifacts of the particular limiting case model.

There is no such thing as 'crush up' or crush down' in BZ. That was introduced in an entirely different paper written 5 years later, called BV and the closure to BV, which is BL

There is no evidence in any of your posts you have ever read it. That is the paper you have supposedly been defending for the last 5 years.

So, if ROOSD is "a better model" than BZ's (which it is in some ways as a math-free casual explanation, and isn't in others) then that means BZ is "wrong," which means that progressive collapse is suspicious, which means that NCSTAR is incomplete, which means... I forget, something about 9/11 and indoor employment that no one even admits to believing any more.

There is no relation whatsoever between ROOSD and BZ. Wrong paper, wrong argument.

There is no way you have read the paper being discussed since the first page of the thread.

 

[Major_Tom]

Great history, Myriad. Thank you.

Fascinating as a study of group cognition and perception.

 

[Bravin Neff]

I'm unsure how serious you are Bravin. I suggest that the issue is more basic than - deeper than - personal "hurt".

I am serious. And few things psychologically are more basic - or deeper - than hurt, along with a subsequent desire to settle scores. Certainly taking polls to see who confused B&V with B&Z is less deep (indeed it is trivial). Certainly trolling for those who took Bazantian blocks too literally is less deep (indeed it is trivial).

The logic isn't hard to understand: if you can't beat them, join them. If you can't join them because they hurt you (or you are too proud), then pretend you are a detached observer studying them like an anthropologist. Hence M_T pretends he is an anthropologist.

"Meanwhile in the Western Hemisphere the Yanamami people emerged with a credit system that served the role of money based on patriarchal honor memes. And during the late anthropocene era, a small tribe known as 'debunkers' emerged, with memes based on a deity known as Bazant and NIST, full of 13 errors related to WTC 1 upper block tilt. Note 'block' is metaphorical."

Except the anthropology is just a charade, and obviously so, although M_T might actually believe in his anthropology mission at this point. Whatever he pretends, it is just score settling.

The behavioural aspects which are loosely labelled "memes" - which reveal M_T's confusion of objectives - he leads with technical issues but asserts that his aim is "anthropological".

My theory explains both: he seeks (or sought) respect and acknowledgement with technical material presented to a technical audience. He didn't get the respect, so he insists he is just being an anthropologist - an anthropologist studying the most boring tribe ever, that of 9/11 debunkers (sorry folks, no offense) who purely coincidentally just happen to be interested in the same general topic he is. Its terrible anthropology work, but then score settling isn't exactly anthropology.

Issues of M_T's "style" which can be seen as "giving as good as he gets" if you read the first page or two of the thread and ask "who started the insulting conduct"

I have read the thread. It is why I suggested an M_T apology thread - I actually meant a thread where folks apologize to M_T.

 

[beachnut]

This paper presents a simplified approximate analysis of the overall collapse of the towers of World Trade Center in New York on September 11, 2001. The analysis shows that if prolonged heating caused the majority of columns of a single floor to lose their load carrying capacity, the whole tower was doomed. Zdeneˇk P. Bazˇant, F.ASCE, and Yong Zhou

..., these guys skipped the BS of the "gravity collapse is and illusion and use a reality based approach... A short cut to the truth...

the floor supporting trusses are sheared off at the connections to the framed tube --- Zdeneˇk P. Bazˇant, F.ASCE, and Yong Zhou

OOS, in 2001... oops

Guess OOS concept was in place with Robertson design in the 70s - don't worry MT, you were only 40 plus years too late to explain a floor fails at 29,000,000 pounds...

OOS???
https://www.google.com/search?rlz=2...&ved=0CCUQ1QJqFQoTCNKwhomlpcgCFVIyiAodz-YFGg#

OOS, Kind of misleading. wide-open, uninterrupted floors, better WOUF, or WUF; much better. GDWUFD - engineer approved, lol

 

[Bravin Neff]

Fascinating as a study of group cognition and perception.

Indeed. The herd behavior is rather pronounced in the elder members, whilst those who joined later can be seen to exhibit similar-albeit-attenuated behavior advancing in what appears to be a step-wise fashion, presumably following a hierarchical system whereby the elders signal their tentative approval, the newer members advance trepidly, and the cycle repeats, eventually culminating into full acceptance by the tribe through several iterations of reciprocating flattery. The newer members that fail to repeat the requisite memes appear marginalized for reasons yet unexplained. A tentative hypothesis revolves around Bazantian blocks whose import the newer members do not appear to fully account for in their appeals.

Or something.

 

[ozeco41]

I am serious.

I thought so but I was not certain. Thanks for clarifying and expanding your explanation.

And few things psychologically are more basic - or deeper - than hurt, along with a subsequent desire to settle scores. Certainly taking polls to see who confused B&V with B&Z is less deep (indeed it is trivial). Certainly trolling for those who took Bazantian blocks too literally is less deep (indeed it is trivial).

Understood and could be. My own career experience - whilst I am a civil engineer - most of my career experience was in managing engineering and related applied science functions and with a large component of conflict resolution/conciliation. Throughout this four- five year saga across several threads and a couple of forums I have tried to take the pragmatic and easy way out by separating the core technical claims from the behavioural considerations. In my opinion the actual technical issues are quite simple and clear cut. Hence my repeated suggestion that we take them from the first foundations - rather than argue later consequences without having a secure foundation for the discussions.

Whilst - as I have said several times - I doubt the behavioural ones are capable of useful discussion in any forum setting with persons interested in 9/11 affairs let alone resolution on this forum. I've several times attracted hostility merely be trying to address the technical issues. Through the 2014 episode through even daring to suggest that the technical issues could be separated from the behavioural. Attack Major_Tom took clear priority over any wish to address the technical matters.

The logic isn't hard to understand: if you can't beat them, join them. If you can't join them because they hurt you (or you are too proud), then pretend you are a detached observer studying them like an anthropologist. Hence M_T pretends he is an anthropologist.

I comprehend that aspect without any difficulty. My choice has consistently been to not try to go there. Other than I think two recent occasions where I acknowledged a core of truth in the "meme" comments and then commended M_T on dropping the global claims and hyperbole whilst I still disagreed with raising the topic on this forum against the background of two way animosity. There are other aspects which contribute to the aggression as well as the hurt which I suggest is not the sole factor. Have you detected the background history of a number of persons who may have seen themselves as valiant explorers rejected by the then JREF?

"Meanwhile in the Western Hemisphere the Yanamami people emerged with a credit system that served the role of money based on patriarchal honor memes. And during the late anthropocene era, a small tribe known as 'debunkers' emerged, with memes based on a deity known as Bazant and NIST, full of 13 errors related to WTC 1 upper block tilt. Note 'block' is metaphorical."

Except the anthropology is just a charade, and obviously so, although M_T might actually believe in his anthropology mission at this point. Whatever he pretends, it is just score settling.

Understood - mostly agreed - except I'm not persuaded of that "just" but that could be my own bias having lived through the history. And my own coping strategy of trying to focus on the technical issues. If you extract M_T from the scene there remains the strong resistance to any review of the underlying technical material. And the not too subtle situations where few members are prepared to explicitly agree to the technical issues when someone like me collates them into a reasoned taxonomic order/hierarchy WHILST asserting most of them are true in separate posts. I haven't done the collation but if I did the table of issues of relevant technical facts versus who has agreed those facts I don't think there would be many blank squares. Set aside all the objections to the name "ROOSD" which are the linguistic equivalent of saying we don't need names for apples and bananas because we have the word "fruit".

My theory explains both: he seeks (or sought) respect and acknowledgement with technical material presented to a technical audience. He didn't get the respect, so he insists he is just being an anthropologist - an anthropologist studying the most boring tribe ever, that of 9/11 debunkers (sorry folks, no offense) who purely coincidentally just happen to be interested in the same general topic he is. Its terrible anthropology work, but then score settling isn't exactly anthropology.

Very much my thinking also. EXCEPT I prefer to throw out the bathwater of "anthropology" WHILST retaining the baby of valid technical claims. And that is the pedantic engineer manager in me. I'm highly resistant to losing the plot AKA "alligators v swamps" problems. And then the whole discussion is overlaid with multiple layers of partial understandings coming from different perspectives plus some outright game playing.

Sorry again about that "not serious" but in the highly charged situation with insults, ridicule and untruth all over the thread I didn't want to take the risk.

I have read the thread. It is why I suggested an M_T apology thread - I actually meant a thread where folks apologize to M_T.

That is the way I understood it. There is also a fair bit of aggressive baggage in Major_Tom's posting on other threads in the years since his polite request which OPed this thread.

I agree your suggestion as a conciliatory move. Ideally it would be two ways but I doubt its practical possibility.

Thanks again Bravin.

 

[ozeco41]

Indeed. The herd behavior is rather pronounced in the elder members, whilst those who joined later can be seen to exhibit similar-albeit-attenuated behavior advancing in what appears to be a step-wise fashion, presumably following a hierarchical system whereby the elders signal their tentative approval, the newer members advance trepidly, and the cycle repeats, eventually culminating into full acceptance by the tribe through several iterations of reciprocating flattery. The newer members that fail to repeat the requisite memes appear marginalized for reasons yet unexplained. A tentative hypothesis revolves around Bazantian blocks whose import the newer members do not appear to fully account for in their appeals.

Or something.

Well said Sir!

As a newbie to this forum - so probably 2009 - I was confronted by a clear hierarchal arrangement with Ryan Mackey as king. (He seemed to have ascended to the throne as heir apparent to Gravy). There were several Princes.

Ryan had done a lot of great work - probably at the leading edge of "debunker" thinking at the time.. An admirable expenditure of effort.

I - the newcomer - dared to risk lèse majesté and politely corrected him on an error of engineering physics. And got slapped down for impertinence. I was right but let it pass not wanting to take on alpha dog at that time - if ever. Then as now my interest is in the technical facts - not "winning or losing" OR ranking of competitors. Ryan totally ignored the advice on physics.

 

[ozeco41]

The only way you can verify this is to understand the step by step derivation of BV equation 12 (the crush down differential equation). You then look at each step to see if joist shearing is consistent with each step.

If you need to verify it. Remember my encompassing claim is specific:
"The later papers by Bazant et al are wrong where they apply 1D simplification models to the WTC real event". I should point out that "where" subsumes "if" - I'll state it even more pedantically if anyone is genuinely confused.

And don't lose track of the overriding burden of proof issue:

IF anyone wants to claim that BV validly applies to WTC real event OR calls up BV in support of an argument that uses that factor either way - it is their burden to prove their assumptions. Not my burden to disprove the assumptions in advance of their claim. That said I stand by my opinion:
"The later papers by Bazant et al are wrong if and whenever they apply 1D simplification models to the WTC real event".

OR even simpler and taking Bazant out of it:

" The 1D simplification models do not apply to the WTC real event." And I've covered my arse on that one several times "unless those claiming they do prove their assumption".

Don't use a differential equation in specific situations that you do not know how to derive, or you will have no idea whether it can be applied in that specific case. Otherwise you are just guessing or believing the claim of another person which you cannot verify.

Sure. Remember that I am questioning validity of the application of the equation so the validity of the equation itself is moot at this stage of my comments.

 

[JSanderO]

If you need to verify it. Remember my encompassing claim is specific:
"The later papers by Bazant et al are wrong where they apply 1D simplification models to the WTC real event". I should point out that "where" subsumes "if" - I'll state it even more pedantically if anyone is genuinely confused.

And don't lose track of the overriding burden of proof issue:

IF anyone wants to claim that BV validly applies to WTC real event OR calls up BV in support of an argument that uses that factor either way - it is their burden to prove their assumptions. Not my burden to disprove the assumptions in advance of their claim. That said I stand by my opinion:
"The later papers by Bazant et al are wrong if and whenever they apply 1D simplification models to the WTC real event".

OR even simpler and taking Bazant out of it:

" The 1D simplification models do not apply to the WTC real event." And I've covered my arse on that one several times "unless those claiming they do prove their assumption".

Sure. Remember that I am questioning validity of the application of the equation so the validity of the equation itself is moot at this stage of my comments.

What's the point of "equations" when there are no real world reliable values to input? These discussions are a strange combination of idealized materials performance and assumed values... mass, temp, and so on... but never applied on the level of detail which shows what is happening. NIST's attempt with sagging trusses and girder walk of was a feeble attempt at this and easily shown (maybe) to be flawed. The take away though not explicitly stated seems to be that twins failed because of trusses and 7 failed because of a single beam expansion leading to a single column failure.

Round and round we go and 14 yrs on and we are getting no where.

 

[Oystein]

...That said I stand by my opinion:
"The later papers by Bazant et al are wrong if and whenever they apply 1D simplification models to the WTC real event".
...

For the record:
I am of this opinion too - and arrived at it because long ago you, ozeco, and not M_T, provided me with convincing arguments to override the tentative authority of Bazant.

M_T quoted (incompletely) and misrepresented a post I made 4.5 years ago in which I questioned his methodoology. By way of example, I picked one question he posed about BL, criticized a methodological flaw in the question (he asked for belief, not claims or arguments), and advised him on how to convince fence-sitters like I was at the time (fully admitting to my lack of competence and information). I don't think M_T heeded that advice back then (but I can't be bothered to check). I guess it must have hurt his butt that I, the incompetent newbee, advised him on methodology, so much that even today, 4.5 years later, he keeps riding that dead horse.


Now I jumped into this thread with both feet in response to a reply you made to Myriad, showing you how you badly misrepresented what he wrote by pretending Myriads scope was wider than it actually was. You have made, and repeated, claims about Myriads past posting (insinuating that he "rested" stuff on BV), but failed to support these claims with evidence, as Myriad asked you to do several times.
I think you and M_T are totally misreading Myriad because you both fail to read him with your meme-blinders off.


Oh, and yes, this all about settling scores

 

[Crazy Chainsaw]

What's the point of "equations" when there are no real world reliable values to input? These discussions are a strange combination of idealized materials performance and assumed values... mass, temp, and so on... but never applied on the level of detail which shows what is happening. NIST's attempt with sagging trusses and girder walk of was a feeble attempt at this and easily shown (maybe) to be flawed. The take away though not explicitly stated seems to be that twins failed because of trusses and 7 failed because of a single beam expansion leading to a single column failure.

Round and round we go and 14 yrs on and we are getting no where.

Exactly why the energetics matter, the few certainties are which ever, mechanism, it has to match the energetics, and collapse times.

 

[BasqueArch]

What's the point of "equations" when there are no real world reliable values to input? These discussions are a strange combination of idealized materials performance and assumed values... mass, temp, and so on... but never applied on the level of detail which shows what is happening. NIST's attempt with sagging trusses and girder walk of was a feeble attempt at this and easily shown (maybe) to be flawed. The take away though not explicitly stated seems to be that twins failed because of trusses and 7 failed because of a single beam expansion leading to a single column failure.

Round and round we go and 14 yrs on and we are getting no where.

Would you kindly refrain from unsubstantiated structural opinions. You are an embarrassment to competent architects.