Analysis of WTC collapses by Nemec and Suranova

[pgimeno]

Great writeup you've provided here Ozeco, but I have a question for the sake of clarity.

Would you apply the same reasoning to Bazant's limiting case?

I must say I hadn't read the paper of Nemec, Juranova et al. Now that I have, I would say that without evaluating its correctness, the only problem I have with it is this bit from the abstract (the highlighted bit):

Abstract: The differential equation of collapse of a high building is derived taking into account many influences. Computer simulation of the collapse of the WTC building is presented using two independent programs for some variations of parameters. The results of both, differential equation and computer simulation, are compared.
​

It is not presented as a limiting case, as one possible model of that collapse, or as a generic collapse. Instead, it is presented as the collapse that actually happened.

Leaving that bit apart, the paper is a theoretical exercise whose correctness or incorrectness is irrelevant in this forum, except maybe to the extent where it can conflict with Bazant and his limiting case, if at all. (I'm surprised to not have seen Bazant's Basher in this thread yet, by the way.)

But outside of the paper, one of the authors said in this very thread:

To: Captain Swoop

We have only shown, that the cause of the collapse of the Twin towers must be different, than the impact of the planes and fire only. [...]

To which I replied that that conclusion doesn't follow from the paper, because it models a very different collapse to the observed one. But you see, it's being pushed as the actual collapse and used to claim there was something else than the planes and the fires. And that's what I have trouble with.

 

[Oystein]

booNyzarC,

thanks for the clarification - but it was unnecessary: I fully agree.
I didn't say the limiting case - looking if collapse could be arrested in the most survival-friendly case - failed. It was fine. That case is:

• All dynamic loads go into columns, the strongest part of the assembly
• The momentum of the top block goes into all columns across the floor area simultaneously and evenly distributed
• Initial velocity of top is equivalent to that reached after a fall through the height of 1 floor

The "fail" arises in later papers, when he tries to refine that model and extrapolate further properties, such as the "crush-down before crush-up" prediction. This does not apply to the real WTC, as the assumptions of the model do not model reality. The top block comes apart at the truss connections as does the bottom part, and columns never again impact columns.

 

[ozeco41]

Ozeco will surely respond to this,...

Mind reader....

I see that there are several questions I need to address. Let's see if I can tackle them in some logical order. Starting with this:

Great writeup you've provided here Ozeco,...

Thank you!

but I have a question for the sake of clarity.

Would you apply the same reasoning to Bazant's limiting case?

Yes - but I would make explicit some things I left unsaid. Those being:
1) "Are the assumptions valid for the purpose?" and
2) "Are the claims made legitimate within the assumptions?"

The answers to those are "Yes" and "Yes" for Bazant.**
They are undefined for Nemec et al....

Let's see why. This is Bazant and Zhou's abstract:

Abstract: 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.

So we have a "simplified approximate analysis" which shows that the tower was doomed if something allowed the top portion of tower to start falling.

I state it that way because that is exactly the starting point assumed by Nemec et al. i.e. the top part of the tower had started falling. So we have like starting points for comparison. Apples with apples if you prefer the colloquialism.

From there Bazant assumed all columns in place - the safest for survival assumption - and showed that there was more than enough energy to cause collapse. Since the actual situation was some columns not carrying load the actual collapse occurred validly within the scope of Bazant's assumptions. So, as I said, "Yes" and "Yes" for Bazant. Bazant was correct.**

Now Nemec et al's abstract says:

Abstract: The differential equation of collapse of a high building is derived taking into account many influences. Computer simulation of the collapse of the WTC building is presented using two independent programs for some variations of parameters. The results of both, differential equation and computer simulation, are compared.

Note it claims "simulation of the collapse of the WTC building" and has an aim of comparing "The results of both, differential equation and computer simulation..." So the only reference to WTC is that it is to be a simulation and that simulation used to compare two methods - this latter not tied to the real collapse.

So:

For me, Bazant's limiting case suffers from the same criticism you apply,...

Whilst the two are superficially similar Bazant uses the "all columns in play" to perform a "simplified approximate analysis" through which he forms valid conclusions about the real behaviour of WTC Twin Towers. Contrast with Nemec et al's use which only sets out to compare methods - not form conclusions about the real event. the aim of comparing two methods probably achieved. But that does not interest me because it is not validly related to the real WTC 9/11 events. Specifically their intended method was to "simulate" and you cannot simulate by using a wrong mechanism. You can put a limit case around a real event and Bazant did so.

So the core of Nemec's claims was "simulation" which he didn't achieve whilst the core of Bazant's claim was "a valid approximation" which he did achieve.

Bazant deliberately used a wrong mechanism but properly allowed for the effects of the simplifying assumption. Nemec et al's assumption could not support a claim of "simulation". And, unlike Bazant, they made no allowance for the scope of the assumption.

however I find it of value and completely relevant. If Bazant's inputs and calculations are accurate (which I believe they are) his case proves global collapse under the best case scenario. Should we not apply the same uniformity of logic to this paper?

Sure - I just spent a couple of hours trying to - there's nothing in the Nemec paper which could be the basis of applying "the same uniformity of logic".

The "uniformity" you should be seeking is not the uniformity of assuming all columns in place. It is how that bit of assumption fits into the argument being made. Bazant's arguments were directed to a valid real world claim about WTC Twin towers. He achieved that aim.

What is Nemec trying to achieve? Does he achieve it? Validly?

I suggest he hasn't even clearly stated an objective.

Which is why, at this stage, I'm not answering a number of questions members have posed. We ain't sure what we are discussing.

We need to get clear what it is we want to discuss before we can progress this mini-discussion.

In my opinion this paper fails because the inputs and calculations are inadequate, not because it fails to mimic the nature of the actual collapse events.

I suggest that neither of those is the reason it fails - see the above material.



** I am specifically and deliberately referring to Bazant and Zhou. The rest of Bazant's work raises a can of worms set of issues. Set them aside till we get this easy one under control.

 

[ozeco41]

...The only point of contention which could be considered legitimate regarding his limiting case is whether or not it truly represents a best case scenario in favor of building survival. If anyone can establish that it does not, they would essentially render his conclusions about the inevitability of global collapse invalid. Nobody has accomplished this to my knowledge, though many have tried and failed.

And even if one were to determine that his case was not in fact a limiting case (i.e. best case scenario in favor of building survival), it still would not support the impossibility of global collapse; that would require much much more.

My emphasis.
A lot of truth in those paragraphs booNyzarC.

The membership of this forum has some strong feelings - two polarised camps plus some in "middle ground".

There are a lot of "NISTophiles" and "Bazantophiles" and, in that context, raising even slight criticism of the two Gods - NIST or Bazant - is lèse majesté which is a capital offence. I've been labelled "truther" on a few occasions for having the gall to criticise the Gods.

With that preamble as arse protection:
a) I have long held concerns that one of Bazant and Zhou's "play it safe" assumptions is of the wrong polarity;
b) BUT I never raise it because there are other factors which over-ride it so it has no effect.
c) ...therefore the heated debate would go nowhere. Other than raise purity of argument considerations.

and on some things I'm a pragmatist.

And I think I've just invented a new oxymoron "Pedantic pragmatist"

 

[Oystein]

...
And I think I've just invented a new oxymoron "Pedantic pragmatist"

If that isn't adopted as the name of a super cool jazz band ("The Pedantic Pragmatists"), it should at least become your member title

 

[ozeco41]

If that isn't adopted as the name of a super cool jazz band ("The Pedantic Pragmatists"), it should at least become your member title

 

[ozeco41]

Here are some brief answers to the questions directed at me:

...So ozeco41, how did the columns fail...

The columns within the scope of this topic are those which failed in the "Global collapse" or "Collapse Progression" stage. Outer perimeter columns nearly all failed by falling away from the tower in various sized sheets and breaking off at the bolted field joints. Core columns cannot say in detail except that failure due to buckling resulting from excessive axial load would/must have been the rare exception if in fact there were any examples.

Sorry, your nice post was close to some short review. But my point was basically: could we formulate some "joint critic" of the paper, in which all agree?

It is possible to formulate a multiple author critique. I don't understand - rather I question the practicality of "...all agree" and you wouldn't get it IMO.

... Never mind, it's not important anyway

Your choice.

...Btw, Czech truthers argue again in sense: why we should read/take seriously any objections of some anonymous "debunkers" on JREF, with avatars like "Maya the Bee"()?

That is a "wrong goalpost" heresy which, sadly, many debunkers support. The issue is "Are the claims true?" NOT "What are the qualifications of the claimant?" A correct claim by a non engineer outranks a wrong claim by an engineer in my opinion.

...In this regard, who has a qualification in structural engineering or similar (just for the case that I. Nemec would like to discuss his stuff here, which is not probable)?

Quite a few including me. Plus some engineers from other branches who are well up to the structural arguments involved.

...Ozeco: thanks again I understand, but is this overall "picture" of collapses you presented something, which is generally accepted by "normal" engineering community? I mean: could it be used in the review?

In reverse order - Yes it could be used in a review as part of an explanation of the actual mechanism of collapse. "generally accepted" is a problem because most of the engineering profession falls into three main camps viz:
A) Not interested in 9/11, don't follow the detailed discussions. Perfectly content to know that the profession at large understands WTC 9/11 collapses AND that there is zero credibility in CD and other CT nonsense;
B) Practising professionals and academics who have been and still are satisfied with abstract models to explain the inevitability of collapses. Generally speaking this group have not tried to align the abstractions with the observed realities of the actual mechanism of collapse; AND
C) Those (Apparently a very small group - including me)...who regard the actual mechanism of collapse as occurred on 9/11 as the foundation for understanding the actual mechanism of collapse as occurred on 9/11. (That re-entrant definition used deliberately. If you want to describe an apple why not use an apple.)

The explanations I have given are based on "actual mechanism" - there will be contention about who does and who does not subscribe to the "actual mechanism" as the foundation of understanding.

All that said it would be practical to build a multi author response - and I doubt that the other 'camps" would seek to disagree.

...Would you apply the same reasoning to Bazant's limiting case?...

See separate and more detailed responses. Yes we should apply the same or analogous reasoning. BUT it is important to address the real argument which is being put by the two competing parties. They both use what seems to be the same assumption of "all columns involved" BUT they use that info in very different ways.

...Should we not apply the same uniformity of logic to this paper?

Already answered - in brief "yes" but it must be truly uniform and truly logical - not simply falling for a shallow appearance of similarity. And both using "all columns fully engaged" is too shallow to be a legit "same argument".

Ozeco will surely respond to this,...

I have. Whilst it is easy to see that Bazant was right and Nemec wrong putting it into a defensible logical argument was a lot harder than I anticipated. I discarded several lengthy attempts - must be getting old or sumptin....

This one by GlennB beat me to answer the legitimate core question raised by MileHighMadness:

By stripping away the lateral support, the columns became effectively weaker than in their original condition. Then there were lateral forces being applied by falling debris to these now 'more slender than they used to be' columns.

 

[Ivan Kminek]

Ozeco: thanks for your answers.

...Meanwhile in Journal of Mechanics Engineering and Automation: the article is now available here.

The abstract is quite different from the version linked at the beginning of this thread:

"This paper is a contribution to the discussion about the fall of the New York World Trade Center (WTC) towers in 2001. The differential equation of the collapse of a high building is derived by taking into account many influences. A computer simulation of the collapse of the WTC building is presented using two independent programs with parameter variations. The results of both, differential equation and computer simulation, are compared resulting correspondences. The authors consider certain probable parameters which would have lessened both the observable speed of the collapse and its extent, however uncertainty regarding the magnitudes of the parameters remains."

 

[ozeco41]

Ozeco: thanks for your answers.

...Meanwhile in Journal of Mechanics Engineering and Automation: the article is now available here.

The abstract is quite different from the version linked at the beginning of this thread:

"This paper is a contribution to the discussion about the fall of the New York World Trade Center (WTC) towers in 2001. The differential equation of the collapse of a high building is derived by taking into account many influences. A computer simulation of the collapse of the WTC building is presented using two independent programs with parameter variations. The results of both, differential equation and computer simulation, are compared resulting correspondences. The authors consider certain probable parameters which would have lessened both the observable speed of the collapse and its extent, however uncertainty regarding the magnitudes of the parameters remains."

It is still one very confused paper. I doubt that there is much point commenting further. My suggestion is wait and see if it attracts any attention. If it does and truthers pick it up and use it we can show that we identified the problems here on JREF. That may happen - it is so vague and woolly that truthers should love it. They can twist it anyway they like.

I won't resist the temptation to make one comment.
Note the ambiguity of focus - Are they analysing what actually happened - forensic analysis of 9/11 events OR are they trying to build a generic model for future towers?
So this "A computer simulation of the collapse of the WTC building is presented..." says "forensic of actual WTC9/11" - except it wasn't a "simulation" as explained previously so they fail on that part whatever purpose they try to use it for.
WHILST "...consider certain probable parameters which would have lessened..." says "we are not talking about WTC actual collapse - we are exploring other variables". That cannot be for WTC 9/11 - they cannot re-write history AFAIK - so must be a generic model. For what buildings? Is anyone going to build "tube-in-tube"???

 

[booNyzarC]

Thank you pgimeno, Oystein, and ozeco.

It has been a long week capped with a long Friday, and without going into too much detail, I've been through some severe familial health issues which hopefully are settled for now.

You are each deserving of a more substantial response than this, but frankly I'm far too tired at the moment to provide you with what you have earned. Suffice it to say that I don't disagree with anything you've said in response to me and I appreciate the depth of your posts very much.

Cheers.

 

[ozeco41]

Thank you pgimeno, Oystein, and ozeco.

It has been a long week capped with a long Friday, and without going into too much detail, I've been through some severe familial health issues which hopefully are settled for now.

You are each deserving of a more substantial response than this, but frankly I'm far too tired at the moment to provide you with what you have earned. Suffice it to say that I don't disagree with anything you've said in response to me and I appreciate the depth of your posts very much.

Cheers.

No problem to provide explanations. If you need more come back when you are not so loaded with other concerns.

Best wishes with the health stuff. I have also had a moderately busy week in that line. Wife had cataract operation Thursday AU time - highly successful.

 

[ergo]

So we have a "simplified approximate analysis" which shows that the tower was doomed if something allowed the top portion of tower to start falling.

No, it doesn't. For the reasons shown by the authors in question, as well as at least a dozen others. There is nothing correct or remotely useful about Bazant's model vis a vis the actual destruction of the towers. Zero.

I'm really fascinated by how often the 9/11 beliebers feel compelled to assure themselves of this silly fallacy. It's like stealth marketing: you're pretending to have real conversations but in actuality are simply pushing a product. A bad product. Why? Why are you pushing this nonsense? Do you really have nothing better to do?

 

[dafydd]

Do you really have nothing better to do?

Yes, but if truthers stopped promoting their delusions then they could do something else.

 

[Newtons Bit]

Sorry, your nice post was close to some short review. But my point was basically: could we formulate some "joint critic" of the paper, in which all agree? Never mind, it's not important anyway
Btw, Czech truthers argue again in sense: why we should read/take seriously any objections of some anonymous "debunkers" on JREF, with avatars like "Maya the Bee"()? In this regard, who has a qualification in structural engineering or similar (just for the case that I. Nemec would like to discuss his stuff here, which is not probable)?

I practice structural engineering to make a living. What now?

 

[Redwood]

Do you really have nothing better to do?

I'm retired from a career in industrial chemistry. Debunking foolish notions is a source of amusement, and a way of keeping the mind sharp.

 

[beachnut]

... Btw, Czech truthers argue again in sense: why we should read/take seriously any objections of some anonymous "debunkers" on JREF, with avatars like "Maya the Bee"()?...?

Are those Czech truthers engineers? Can someone summarize their paper? I have read it, and the conclusion does not seem to be a conclusion, and the narrative seems to have the real conclusions hiding in the text. What are the main points, and implied conclusion?

With truthers like Balsamo saving bullets or a rope for those who call his claims nonsense.

If 911 truth had valid claims, they would be able to team with a news paper and earn a Pulitzer for breaking the big inside job. Where is there evidence. The paper can't give a valid time or analysis of the real collapse, how could they model it?

 

[beachnut]

... Btw, Czech truthers argue again in sense: why we should read/take seriously any objections of some anonymous "debunkers" on JREF, with avatars like "Maya the Bee"()?...?

Are those Czech truthers engineers? Can someone summarize their paper? I have read it, and the conclusion does not seem to be a conclusion, and the narrative seems to have the real conclusions hiding in the text. What are the main points, and implied conclusion?

With truthers like Balsamo saving bullets or a rope for those who call his claims nonsense.

If 911 truth had valid claims, they would be able to team with a news paper and earn a Pulitzer for breaking the big inside job. Where is there evidence. The paper can't give a valid time or analysis of the real collapse time, how could they model it?

 

[ozeco41]

Are those Czech truthers engineers?...

It sure looks like it. A sad reflection.

...Can someone summarize their paper?

Overall the paper is very confusing and mixes up two poorly defined objectives. However the content of the paper can be summarised by two points:
1) The closest thing to a clear objective is that they wanted to compare two methods of analysing collapse of towers such as WTC. They did that comparison and found that the two methods gave similar results. The maths analysis may be wrong - I haven't bothered digging into that aspect - but it is meaningless anyway BECAUSE
2) They claim to have simulated WTC Twin tower collapse and that claim is false. They assumed that the columns were in place for the "Global collapse" which most members here would understand is false. My previous posts tried to explain that aspect.

I have read it, and the conclusion does not seem to be a conclusion,...

Its not a good conclusion but there are two bits of conclusion:
(i) "...both computer programs gave comparatively similar results." AND
(ii) "...the approximation to the reality is better."
Which are "So what?" and "Misleading crap" respectively.

...and the narrative seems to have the real conclusions hiding in the text.

this one is lost in the body:
"...the fall of the building would stop after falling cca 80 m."
Whether that claim is true or not it only applies to the faked up building they analysed - it is not valid for the real WTC which collapsed on 9/11.

They also talk about using different parameters so they cannot be dealing with the real WTC Towers.

The paper can't give a valid time or analysis of the real collapse time, how could they model it?

Correct. It doesn't relate to the real WTC collapse and they did not simulate the real collapse.

My opinion, E&OE, is that this is another of those papers which may fool the gullible but won't stand up to scrutiny. And it is a pity it comes from academia.

 

[beachnut]

It sure looks like it. A sad reflection.
Overall the paper is very confusing and mixes up two poorly defined objectives. ... it is a pity it comes from academia.

Good summary. Thank you. Wanted to see if I read the same paper - your summary confirms what I read.

 

[ozeco41]

Good summary. Thank you. Wanted to see if I read the same paper - your summary confirms what I read.

Thanks.

It was PITA to read.