Bazant in a nutshell

[DGM]

So if this isn't the original then perhaps someone should let his son know this and direct me to the original original.

I don't think I need to show his son (it's referenced but the link is no longer valid) but, I'll show you.

http://www.civil.northwestern.edu/people/bazant/PDFs/Papers/404.pdf

 

[pgimeno]

The paragraph in question came from the paper printed in..
"Journal of Engineering Mechanics ASCE, in press 9/13/01, Expanded 9/22/01, Appendices 9/28/01"
can be found here http://www-math.mit.edu/~bazant/WTC/WTC-asce.pdf

It wasn't from several months later.

"in press 9/13/01" is a reference to the SIAM News paper. Look at the list of publications here: http://www.civil.northwestern.edu/people/bazant/PDFs/publicat.pdf:

404. Bažant, Z.P. (2001). "Why did the World Trade Center collapse?" SIAM News (Society for Industrial and Applied Mathematics) Vol. 34, No. 8 (October), pp. 1 and 3.
a) Bažant, Z.P. (2001). "Anatomie zániku dvojčat" (Anatomy of ruin of twin towers), Věda a technika (Science and Technology) [publ. by Hospodářské noviny (Economic News)] No. 186, p.1 (Sept. 25, 2001), Prague (abbreviated Czech translation of item 404).
b) Bažant, Z.P., and Zhou, Y. (2001). "Proč se zřítily věže World Trade Center? (Why did the towers of World Trade Center collapse?), Stavitel (Builder) (Prague) Vol. 9, No. 10 (October), 35 (expanded Czech translation of item 404).
c) Bažant, Z.P., and Zhou, Y. (2001). "Dlaczego runȩty wieżowce World Trade Center?" (Why did the towers of World Trade Center fail?) Polski Cement (Warszaw) No. 4 (Sept.-Dec.), pp. 56-57 (expanded Polish translation of item 404).

405a. Bažant, Z.P., and Zhou, Y. (2001). "Why did the World Trade Center collapse?--Simple analysis." Building Research Journal 49 (3), 135-146 (authorized modified republication of item 405, and major expansion of item 404).
b) Bažant, Z.P., and Zhou, Y. (2001). "Why did World Trade Center collapse?--Simple analysis." Archives of Applied Mechanics (Springer, Berlin) 71, 802-806 (authorized abbreviated republication of item 405).
c) Bažant, Z.P., and Zhou, Y. (2001). "Why did World Trade Center collapse?--Simple analysis." Int. J.of Structural Stability and Dynamics 1 (4), 603-615 (authorized abbreviated republication of item 405).
d) Bažant, Z.P., and Zhou, Y. (2001). "New York e World Trade Center: Analisi del crollo." Il Giornale dell'Ingegnere No. 20/21, December 2001, pp. III-VI (authorized Italian translation of item 405).
e) Bažant, Z.P., and Zhou, Y. (2001). "Why did World Trade Center collapse?--Simple analysis." Studies and Researches (Politecnico di Milano, Italy 22, 229-242 (authorized abbreviated republication of item 405).
f) Bažant, Z.P., and Zhou, Y. (2001). "Γιατί κατέρρευσαν αι πύργοι του Παγκόσμιου Κέντρυυ Εμπορίου; -- Μια απλή ανάλυση." ΤΕΧΝΙΚΑ ΘΕΜΑΤΑ (Patras), Vol. 46, Dec., 36-44 (authorized Greek translation of item 405 by P.A. Kakavas).
g) Chinese translation of item 405 in Advances in Mechanics (Beijing) 32 (4), 613-624 (2002).

2002​

405. Bažant, Z.P., and Zhou, Y. (2002). "Why did the World Trade Center collapse?--Simple analysis." J. of Engrg. Mechanics ASCE 128 (No. 1), 2-6; with Addendum, March (No. 3), 369-370.
h) Bažant, Z.P., and Zhou, Y. (2002). "Pochemu razrushilsya Vsemirnyi Torgovyj Centr?--Uproshchenyi analyz." Budainictva (Stroitel'nost', Construction, Minsk, No. 1-2, 180-199 (authorized Russian translation of item 405 by V.M. Ovsianko).
​

 

[ozeco41]

I don't think I need to show his son (it's referenced but the link is no longer valid) but, I'll show you.

http://www.civil.northwestern.edu/people/bazant/PDFs/Papers/404.pdf

The important thing about this Bazant and Zhou paper is to remember how much of it is not relevant to the actual 9/11/2001 collapse mechanism.

The pink shaded bit says this:

The vertical impact of the upper part falling onto the lower part generates vertical loads much higher than the load capacity in the columns of the underlying floor (stage 4), even if these columns have not been heated. The columns of the lower floor thus buckle, too.
[....
....lots
....edited
....out
....]
In spite of the approximate nature of this analysis, it is obvious that the elastically calculated forces in the columns caused by the vertical impact of the upper part must have exceeded the load capacity of the lower part by at least an order of magnitude.

(My emphasis) Since the stage of collapse they are talking about did not involve the columns the way they assume all that pink shaded stuff is irrelevant.



(Please don't try to expand the graphic - I have compressed it to save bandwidth. )

 

[DGM]

The important thing about this Bazant and Zhou paper is to remember how much of it is not relevant to the actual 9/11/2001 collapse mechanism.

I agree. This is why I wonder if lexicon008 is even talking about the same paper. He (?) complains that it was written so quickly but doesn't understand the purpose of the paper.

Funny thing. An CT could easily use this paper in support of CD, instead they ignore it and claim huge amounts of explosives (or whatever) would be needed. If only they understood.

 

[lexicon008]

Thank you for directing me to the original paper..I was obviously in error (google obviously is not my friend)

 

[DGM]

Thank you for directing me to the original paper..I was obviously in error (google obviously is not my friend)

You're welcome.

Do you understand how this applies and how he was never risking his reputation?

 

[ozeco41]

I agree. This is why I wonder if lexicon008 is even talking about the same paper. He (?) complains that it was written so quickly but doesn't understand the purpose of the paper...

lexicon is working through the issues and I wish him well as he progresses.

However the speed of publishing and purpose of the paper are some of the key reasons for the widespread and ongoing confusion:
A) The Bazant & Zhou paper - whichever version - was a trivial exercise within clearly limited boundaries;
B) As such it met the criteria of "publish or perish" so critical to academics. i.e. Bazant got out there first. Everyone else was second, third,.....later;
C) If we interpret it in that context and with sound "top down" reasoning there is no problem, no confusion or at least we can work through remnant confusion.

BUT if we try 12 year hindsight from a different direction and using truther style "work up from the details" so called "reasoning".....confusion is near certain guaranteed. Working up from details is always harder even if it is possible, And there can be no "working up from details to prove CD" because there was no CD - the end point does not exist for their arguments. No wonder they are confused....there's nowhere to go down their chosen road.

Getting it in perspective and coming at the problem from the easier direction are therefore the two biggest issues.

...Funny thing. An CT could easily use this paper in support of CD, instead they ignore it and claim huge amounts of explosives (or whatever) would be needed. If only they understood.

If they could understand they wouldn't be truthers.

....And that is not IMNSHO a trivial comment.

The most evident difficulty facing many truthers is their inability to process reasoned argument which works from the safe ground of a known context and deals with such details as are necessary to progress the argument.

They are "divergent thinkers" when the need is for "convergent thinking". A lot of debunkers have the same problem but such debunkers have two big advantages viz:
1) They are ultimately on the winning side - there was no CD; AND
2) All the necessary thinking has already been done for that "winning aside". No need for most to work it out for themselves - all they need to say is "me too!"

The truthers have the two complementary problems:
- they are on the losing side - there was no CD; AND
- nobody from that side has ever put forward a persuasive argument for CD so they have no reasoned argument to parrot as "Me too!".

 

[ergo]

Some misunderstandings related to WTC collapse analysis

It should no doubt interest some in this thread that Tony has a new paper published, written with Gregory Szuladzinski and Richard Johns, in the International Journal of Protective Structures, Vol. 4, No. 2, which came out this past month.

Some misunderstandings related to WTC collapse analysis

I understand as well that the article he submitted with Richard Johns to the JEM in May 2011 continues to sit with the editors there who have told him on several occasions that they intend to publish it.

 

[ozeco41]

It should no doubt interest some in this thread that Tony has a new paper published, written with Gregory Szuladzinski and Richard Johns, in the International Journal of Protective Structures, Vol. 4, No. 2, which came out this past month.

Some misunderstandings related to WTC collapse analysis...

Interesting link there ergo - I knew the paper had been published but did not have a link that accessed the paper without a fee being charged. So I took a look to see if the paper adds anything to WTC 9/11 collapse discussion?

This is the introductory paragraph:

This presentation is not so much about how the WTC towers failed, but about how they could not fail. The objective is to eliminate erroneous concepts supported by false assumptions and by the use of incorrect values for velocity, mass, and column resistance. The only complete hypothesis of the global collapse mechanism of the Towers is a successive flattening of stories associated with compressive column failure and referred to as a Progressive Column Failure mode or PCF in brief. (In the past this mode was often referred to as pancaking, but this term is not used here to avoid ambiguities). It is explained here why PCF could not be the mode of the ultimate destruction....

OK let's take it point by point:

This presentation is not so much about how the WTC towers failed, but about how they could not fail....

Interesting goal...Why take that as the objective when explaining how they did fail would seem to be more appropriate? For example I am confident I could show that the towers did not collapse as a result of overloading by Santa's Custard accidentally dropped from the sleigh...

The objective is to eliminate erroneous concepts supported by false assumptions and by the use of incorrect values for velocity, mass, and column resistance.

Good goal but obviously a subordinate goal to explaining what are the more correct values. Still members with views ranging from mine across to Major_Tom's should support it.

The only complete hypothesis of the global collapse mechanism of the Towers is a successive flattening of stories associated with compressive column failure

FAECES OF THE MALE BOVINE That bit is totally false. Probably the dead hand of Szamboti - it is his trademark of making false assumptions to ensure that the argument leads to his predetermined false conclusion.

and referred to as a Progressive Column Failure mode or PCF in brief.

I have no problem with what they call it but many forum members are on record for ridiculing acronyms which are derived from initial letters - eg "ROOSD". Those members, if they are consistent, will need to ridicule this one.

(In the past this mode was often referred to as pancaking, but this term is not used here to avoid ambiguities).

Agreed with both.

It is explained here why PCF could not be the mode of the ultimate destruction....

They are a bit late. It wasn't the mode of failure. Why write a paper on what wasn't? It is received wisdom here on JREF that "PCF" was not the collapse mode. Some members deny it when labelled "ROOSD" or when Major_Tom says it....but the underlying concept is accepted. And "PCF" is not. Other than by some Ultra BazantoPhiles.

It should be a big yawn to the BazantoPhobes and a non-event to Bazant agnostics like me.

In brief the intro is the same style as four previous Szamboti papers I have read and critiqued. He sets a limit assumption to favour his predetermined outcome.

However if I give this a positive spin - they set out intending to show how the Twin Towers did not fail -- "but about how they could not fail" -- picked a way that we all know is not how they really did fail -- and seem to have proved their point. Viz: "The towers did not fail the way we know the towers did not fail". On that point I agree. They got that bit right. Seems a bit circular, a bit redundant and why it needs a paper I don't know but....

I may read more and make some comments.

 

[JSanderO]

This may be off topic... more or delete as necessary.

Re twin towers collapse initiation

No one can deny that the plane impacts destroyed a number of load paths. The loads above therefore had to be redistributed to those which remained. Some remaining were damaged and probably could not take the additional loads and they buckled. A guess.. we don't know.

We also observed extensive raging fire fueled by some amount of Jet A and the flammable contents of the towers. This obviously had the effect or eroding the steel'sn ability to perform... ie carry loads. Whatever the ultimate strength was stone cold and properly braced, it was dropping as the heat effects aggregated.

The aggregation of heat weakening did not abate as apparently the fires continued until the tops were released. This period likely included additional loss of bracing from warping and expansion of the steel from heat. A good assumption is that the aggregate yield strength of the load paths was being driven down and some individual members likely were driven to below their yield strength, then failed and the redistributed loads that individual member was supporting was then redistributed to the remaining load paths. This was what let to the progressive and rapidly increasing erosion of aggregate axial load path capacity. When that dropped below the actual service loads... the remain columns buckled (severely) and this caused some translation of the frame and release of the top... which then proceeded to deliver the ROOSD mass to the slabs... which then destroyed more bracing in the core below... which then led to the facade losing bracing and grew unstable as a result and toppled away... and finally the remaining core columns succumbed to Euler buckling forces and there as little left.

Or so it appears.

 

[MarkLindeman]

Two loose ends slightly bothering me:

Perhaps i'm not a fan of the papers title.
"Why Did the World Trade Center Collapse?—Simple Analysis"

the first part implies that the paper is explaining the actual collapse dynamics (maybe i'm reading too much into it)
the second implies that the collapse was a simple thing..which it wasn't..block diagrams just don't work when the blocks are made up of thousands of parts that were shredded during the collapse.

A few posters have riffed on the word "simple," but just to be clear: "simple analysis" doesn't imply that the collapse was simple. It just doesn't. It really does describe the analysis.

For instance, the greenhouse effect can be described by analyses ranging from a single equation to global models that run slowly on supercomputers. Obviously a single equation can't describe every aspect of climate change, but it may be very well suited to explore a particular aspect. Or not. Regardless of what one thinks of any particular simple analysis, the term isn't fraught with the connotations that lexicon008 seems to have read into it.

Actually it was. If you look in the references:

Jirasek, M., and Bazant, Z.P. (2002). Inelastic Analysis of Structures. J. Wiley and Sons, London and New York.

You don't normally see a reference to the future.

This is of course a side issue, but it's pretty common to see references to the future. This can happen for two reasons: sometimes copyrights are postdated (this text in fact was copyright 2002, but Amazon says it was published in November 2001), and providing a future date may seem more useful than stating the date as "forthcoming" -- especially when the text being referenced is likely to be published before the manuscript that references it!

The PDF in question apparently was created on 10/18/2001. I don't know which sentences were written by 9/13, by 9/22, or perhaps later. But I think the passage under discussion is pretty early, even though it didn't appear in SIAM News. (I don't think it really matters.)

 

[ozeco41]

Well I've read through the rest of the paper which ergo linked.

There is a lot of truth in it - lots of variants focussed on why Bazant's later papers following Bazant and Zhou 2001-2 were wrong plus some shortcomings identified in B & Z.

So nothing new - the issues identified many times here. Discussed extensively here and a big theme of Major_Tom's postings.

Near the middle of the paper we see this:

Thus, in 2008, the PCF mode was demonstrated to be an inadequate explanation of the building collapse. Yet, some insist on ignoring the numbers. A recent publication [6] implies that [2] was entirely correct and says: The collapse of the World Trade Center towers was initiated by the impact of the upper part falling onto the underlying intact story. The use of Eq.1 in [6] amounts to assuming a free drop, by one story.

Well the 'in 2008' is near enough as to time but only goes half way. Me 2007 and M_T 2009 and undoubtedly others not only discarded PCF but put forward what really happened. M_T introduced 'ROOSD' as his label and has been ridiculed for it. By people who dodge around the fact that it labels the mechanism which really happened.

And both of us have been soundly chastised many times for committing lèse majesté against Bazant (and NIST and probably a few other allegedly untouchable gods.) I plead guilty.

They correctly identify that the assumption of a one storey free drop pervades much of the published work and that it is nonsense. Interesting to see T Sz's name on a paper which does that - it changes the status of that infamous 'jolt' from 'missing' to 'never could be'. There has been little serious discussion of the actual mechanism of the cascade failure of 'initiation' and the transition to ROOSD. So I wont start to explain it here but the one storey free fall is nonsense.

The penultimate sentence of the paper reads:

The presentations in these papers are not a valid description of what happened.

Which is true enough. But the tedious mathematics way of proving it is a lot of wasted effort. What really happened is accessible to gross visual observation and a bit of thought. The pattern of using complex maths is familiar for at least one of the authors. As I said in my first post on the internet:

The paper referenced as Engineering Reality by Tony Szamboti is typical of many which look impressive in detail to the non-engineer. The complex calculations may even be correct but the base premises are faulty....

The base premises in this instance not wrong - it's just an inefficient process of proving what we here on JREF already knew. Ditto The911Forum. Maybe it is only academia which hasn't worked out what really happened.

The last sentence of the conclusion reads:

...The reasons for a smooth motion history and promptness of collapse of the North Tower remain yet to be determined...

Not true. And Tony Sz as a member of this forum and The911Forum must know that the statement is not true. Maybe anyone who explained it back then should publish?

But, please, no suggestions that M_T and I do a joint paper.

 

[ozeco41]

This may be off topic... more or delete as necessary.

Re twin towers collapse initiation

No one can deny that the plane impacts destroyed a number of load paths. The loads above therefore had to be redistributed to those which remained. Some remaining were damaged and probably could not take the additional loads and they buckled. A guess.. we don't know...

Actually we do know near enough. And it is not a "guess". We know that the top portion of the towers fell. That means that every column had failed. And we know that there was no CD. Plus buckling is the most likely mechanism in the context of the cascading failure.

...
...[middle part of post non contentious - edited]
...and finally the remaining core columns succumbed to Euler buckling forces and there as little left.

I'm not convinced of that

specifically the core collapse was almost certainly dominated by strip down /shearing off of the horizontal beams analogous to the ROOSD shearing of OOS floors. The loads imposed on the columns was almost certainly well below Euler buckling level. And the spires hardly significant other than as partial evidence supporting the "strip down" process.

 

[JSanderO]

The strip down process as you call it is what increased the slenderness ratio for the core columns from 1/12 (slightly less than) to as much as 1/200 or more. It's hard to calculate I would imagine because at some level (flr 50 or so) the column size reduces and so the short axis (governing) is less.

The unbraced columns were exceeding the slenderness ratio limit for steel columns... and as they were composite... one stacked on the next with some thin(ish) splice plates... the swaying motion from the instability (Euler forces, wind etc.) broke the (a) joint and the upper portion was precariously perched on the lower and slipped off and dropped like an icicle. Perhaps some buckled at blew apart the joints... clearly way way weaker than the column cross sections.

 

[pgimeno]

It should no doubt interest some in this thread that Tony has a new paper published, written with Gregory Szuladzinski and Richard Johns, in the International Journal of Protective Structures, Vol. 4, No. 2, which came out this past month.

It's still the wrong thread. The "Applicability..." one is much more suitable. But Ozeco did a good dissection already so I don't think it deserves any further commenting. I'll just say that "pancaking" of floors and "progressive column failure" have nothing to do with each other: floor pancaking involves no columns, and the excuse of ambiguity is disingenuous, as it hasn't ever been used on anything involving columns.

We don't want to convert this thread into another Szamboti thread, do we?

 

[ergo]

I'll just say that "pancaking" of floors and "progressive column failure" have nothing to do with each other: floor pancaking involves no columns, and the excuse of ambiguity is disingenuous, as it hasn't ever been used on anything involving columns.

Who is using an excuse of ambiguity? What published paper are you referring to that claims to explain the "pancaking" collapses of the towers?

We don't want to convert this thread into another Szamboti thread, do we?

Lol. Why do you have a thread on Bazant then? You yourself have just stated his analysis is irrelevant.

 

[Dave Rogers]

But, please, no suggestions that M_T and I do a joint paper.

How about you, M_T and Tony?

Dave

 

[ozeco41]

How about you, M_T and Tony?

Dave

Since I have posted many thousands of words to help each of them see the error of their ways I somehow doubt the viability of that process.

However I understand the common pecking order for co-authors. The first name there to attract attention - those lower down do the writing work - Guess who wrote Bazant and Zhou. Certainly Tony's name has more notoriety market recognition than my real name or either of my posting user names.

So if it was authored by "SZ, M_T and ozeco" we could get the two of them in print on something I wrote....

....cannot say the next bit - I'm too modest....




BTW It would have to be "Szamboti T, Thomas M and Conley E" knowing Tony's view that putting your real name on it by some magic makes it irrebuttably true.

 

[carlitos]

deleted upon reflection

 

[ozeco41]

deleted upon reflection

Probably a good move.

I'm usually too slow to do it.