Critiquing Bazant: Now and Zen

Commentary on the Bazant and Verdure article Mechanics of Progressive Collapse: Learning from World Trade Center and Building Demolitions; page 308; JOURNAL OF ENGINEERING MECHANICS (© ASCE); MARCH 2007:

by ShineOn*

At the outset it should be noted that if the articles published by Dr. Bazant are even modestly on target with regard to the analysis of the progressive collapse of the WTC Towers and (WTC 7), this still does not preclude the possibility that planted explosives were used to make sure that the demolition of the these buildings was achieved. This is basic logic and is contrary to one of his listed reasons for writing (and publishing) this latest article (2007):

“It could also help to clear up misunderstanding (and thus to dispel the myth of planted explosives).”

The formal fallacy of the above statement shows what appears to be a predisposition on the part of Dr. Bazant to only be willing to support one interpretation of these collapse events, namely that the airplanes and subsequent fires were the only causes of the rather “interesting” collapse sequences (dynamics) observed for the WTC Towers and WTC 7 on 9/11 (referred to throughout this commentary as the “official conspiracy story”).

These sorts of mistakes (of logic and/or fact) actually begin with the very first sentence of the recent article (2007). The first two parts of the first sentence of this paper states:

“The destruction of the World Trade Center (WTC) on September 11, 2001 was not only the largest mass murder in U.S. history, but also a big surprise for the structural engineering profession…”

The propaganda nature of the first part of this first sentence not withstanding, it really does not take a great deal of effort to refute such an absolute and poorly researched statement from Dr. Bazant. However, based on the definition of mass murder as “the act of murdering a large number of people, typically at the same time, or over a relatively short period of time,” perhaps it merely depends on what a person considers to be a relatively short period of time. This might suggest (at the very least) that Dr. Bazant does not consider the span of hours, days, months, years, decades, or even centuries to be a relatively short period of time.

And then a little further on in this recent article from Dr. Bazant there is the following passage that is worthy of some consideration:

“As generally accepted by the community of specialists in structural mechanics and structural engineering (though not by a few outsiders claiming a conspiracy with planted explosives), the failure scenario was as follows: …”

It is lamentable that a peer reviewed journal of this caliber has allowed for such a pitiful logical fallacy of “appealing to the majority” as a method of evincing an argument of what might have been the causes of the WTC building collapses (specifically the WTC Towers and WTC 7) on 9/11. What is said above by Dr. Bazant can be parsed as meaning that if you don’t “believe” the official conspiracy story, then you are an outsider and a conspiracy theorist; it is basically a rehash of the tired and over used mantra of “either you are with us or against us.” Of course, the official conspiracy story is also a conspiracy theory, so it appears that Dr. Bazant is willing to employ this rather over used “straw man” logical fallacy that has been the work horse of media manipulation for some decades already. It really is a sad day when a distinguished professor makes use of two rather ludicrous logical fallacies in a single sentence in the pursuit of scientific inquiry.

And besides which, the above passage from his article does not jive too well with the second part of the first sentence of the article. Am I supposed to believe that the initially surprised structural engineering community has come to their collective senses and now realize the correctness of the official conspiracy story in describing the destruction of the WTC Towers and WTC 7 on 9/11? Or is this just another instance of “catapulting the propaganda?” Of course, the detailed report on WTC 7 has yet to be completed.

Now, keep in mind that Dr. Bazant is partially trained as a theoretical physicist, specializing in classical mechanics, so it is expected that he will communicate his ideas with considerable accuracy and precision. Not only does he appear to fail at this task (e.g. does the “largest mass murder in U.S. history” include those perpetrated by the USA on other groups, both inside and outside the USA?), but he also makes claims with far too much certainty and far too little (if any) doubt; by now he should be expressing an abundance of doubt and skepticism towards the official conspiracy story in his recent article (2007) on this topic of the collapses of the WTC Towers and WTC 7, especially given the many well known observations that contradict his original analysis (2002). The history of science (and human affairs in general) is littered with such examples of people who have the appropriate training that choose to attack the messenger and ignore the observations, arguments, and reasoning that point to flaws in their hypothesis and/or the results derived from them. On this matter I am reminded of the thoughts of Hakuin that are also applicable to those of us that work in the physical sciences:

“For the study of Zen there are three essential requirements. The first is a great root of faith; the second is a great ball of doubt; the third is a great tenacity of purpose. A man who lacks any one of these is like a three-legged kettle with one broken leg.”

And we all know what happens to a kettle that has a broken leg…it will tip over on its side. And we might expect a similar behavior to occur for a tower that suffered asymmetric damage and began to collapse. In the case of collapsing buildings we certainly have no reason to believe a priori (as Dr. Bazant apparently wishes for us to do based on simple models) that the collapses of the WTC Towers and WTC 7 should progress with a high degree of symmetry all the way to their foundations without some additional help in the form of controlled demolition devices. I am quite troubled by the lack of integrity on the part of people and agencies in not considering the possibility of the controlled demolition hypothesis. It appears these people and agencies see it as their mission to only consider supporting the official conspiracy story; at a minimum this is bad science and at a maximum it will perhaps turn out to be complicity after the fact.

If a theoretical physicist chooses to set up a physics problem with the intent of achieving a desired conclusion (while ignoring relevant facts and/or observations to the contrary), it may in some cases (such as in the simple models developed by Dr. Bazant) be possible to do so. But this does not necessarily indicate that the assumptions and/or approximations that went into setting up a given model are correct or that the conclusions derived from them can or do correctly account for the observed reality, even if at first glance they appear to do so.

And this latter issue of matching theory with observations (experiments) is the bedrock upon which the “scientific method” is built. I’d at least expect an honest and ethical scientist to acknowledge this point and state the obvious limitations of their initial assumptions and approximations at some point in a given article on a given topic, especially one as complex as collapsing steel framed high-rise towers, and also to suggest real world experiments that could help to prove or disprove a given model.

Instead of performing to this sort of expected level of academic and intellectual integrity, Dr. Bazant chooses in the recent article (2007) to steadfastly rely on the conclusions of his own previous simplified model (2002), which for many (or most) of us paying a modest amount of attention now know, based on a total review of all the relevant evidence, both physical and otherwise, is to an unreasonably high degree of probability likely to be incorrect:

“In broad terms, this scenario was proposed by Bažant (2001), and Bažant and Zhou (2002a,b) on the basis of simplified analysis relying solely on energy considerations. Up to the moment of collapse trigger, the foregoing scenario was identified by meticulous, exhaustive, and very realistic computer simulations of unprecedented detail, conducted by S. Shyam Sunder’s team at NIST. The subsequent progressive collapse was not simulated at NIST because its inevitability, once triggered by impact after column buckling, had already been proven by Bažant and Zhou’s (2002a) comparison of kinetic energy to energy absorption capability.”

The above passage makes it clear that not only has Dr. Bazant in this recent article (2007) declared that there is no need for large computer simulations of the collapse dynamics, he is also contradicting what he had previously claimed in the first article (2002), namely that such large computer simulations would be appropriate:

“The details of the failure process after the decisive initial trigger that sets the upper part in motion are of course very complicated and their clarification would require large computer simulations. For example, the upper part of one tower is tilting as it begins to fall ~Appendix II!; the distribution of impact forces among the underlying columns of the framed tube and the core, and between the columns and the floor-supporting trusses, is highly nonuniform; etc. However, a computer is not necessary to conclude that the collapse of the majority of columns of one floor must have caused the whole tower to collapse.”

And even in the above passage Dr. Bazant is thrashing about trying to convince us that large computer simulations of the dynamics of the collapse of the WTC buildings are not necessary, claiming instead that the simplified analysis he has presented is enough to “prove” what would happen.

Now, these statements above in the first article (2002) from Dr. Bazant should get the attention of nearly all physical scientists as being quite suspicious and capricious, since we all know that simplified models generally depart from more comprehensive and detailed models on a range that goes from small differences that are relatively inconsequential out to large differences that are quite instructive in showing the limitations and inaccuracies in derived results that often arise from making too many simplifying assumptions and/or using unrealistic approximations. There are also a great many instances when simple models do not even allow for certain observed behavior in real world physical systems, and it is only when some small perturbation is accounted for that the models actually begin to predict what is observed in experiments. And for a complex and large extended structure like the WTC buildings, claiming that the derived results of simple models as “proof” of what would happen seems at best to be disingenuous when coming from a person with the training and achievement that Dr. Bazant has acquired.

In the addendum to the first article (2002), Dr. Bazant suggests that large computer simulations might reveal differences of a factor of 2, but again he does not show enough doubt (or perhaps humility) in recognizing that the differences seen in large computer simulations of the collapse dynamics could amount to a couple of orders of magnitude. At least as disturbing (and perhaps more so from my perspective) is his lack of interest in the symmetry of the dynamics of collapse, as this would be a major blow to the simplified models presented by Dr. Bazant if large computer simulations could not reproduce the observed nearly complete and relatively symmetric collapse sequences of the WTC Towers. (Of course, the problem with such a possible mismatch could be with the large computer simulations, but this could quite appropriately be investigated more thoroughly through controlled experiments.)

It is also quite reasonable for us to expect an honest and ethical discussion (or analysis) by Dr. Bazant to have at least questioned or complained about the lack of completeness and transparency in presentation (that might properly be considered a foundation principal of the “scientific method”) on the part of NIST in not releasing all of the details of their computer simulations, even though these (supposedly) only deal with the lead-up to the collapse (initiation) trigger. Instead, Dr. Bazant appears to embrace the computer simulations performed by NIST while basically ignoring the necessity of conducting exhaustive real world experiments to help confirm this type of theoretical modeling, which, of course, is a major breach of the proper application of the “scientific method.”

Dr. Bazant has set up the “analysis” of the problem of these collapsing buildings by dividing them into two distinct parts, the collapse trigger (for the initiation of a collapse) and the subsequent progressive collapse. Furthermore, the problem has been tacitly set up in the first paper (2002) with the assumption of a symmetric trigger (initiation event):

“For our purpose, we may assume that all the impact forces go into the columns and are distributed among them equally. Unlikely 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. If the building is found to fail under a uniform distribution of the impact forces, it would fail under any other distribution.”

But what might the more probable asymmetric failure mode look like in the real world? Dr. Bazant does not ventures into a discussion (or analysis) of what we might expect to observe if the collapse trigger is asymmetric or if the collapse trigger is asymmetric and these two (supposedly distinct) events – collapse trigger and progressive collapse – are not well isolated in time, but instead were considerably overlapped in time. While it is quite reasonable to state that a given force concentrated in a smaller area will cause more damage at the impact location(s) than if that same force were spread out uniformly over a larger area, it is an unsubstantiated leap of logic to imply that the outcome for these different scenarios would necessarily result in nearly identical dynamics. Furthermore, as Dr. Bazant even stated, the former case of an asymmetric collapse trigger is much more likely (based on a qualitative argument of the behavior of distribution functions). What then would an asymmetric collapse trigger and perhaps a mixing in time of these two events – collapse trigger and progressive collapse – mean with regard to the observed dynamics of a progressive collapse? Is this somehow related to the refusal of NIST to make available to us “outsiders” all of their computer simulation data? Many of us apparently have an intuitive sense that the observed nearly complete and relatively symmetric collapse sequence of any one building on 9/11, let alone three buildings, is about as probable as seeing a tossed coin land on its edge and stay in this relatively unstable configuration. A more rigorous analysis invoking stability theory would seek to address the role that perturbations would play in the expected dynamics of the events observed on 9/11. I certainly find it difficult to believe a priori that enough of the building support structure would fail nearly simultaneously (or in a short enough period of time) based only on asymmetric airplane impact damage and what were most likely to be asymmetric fires to produce the observed nearly complete and relatively symmetric collapse sequences of the WTC Towers. And even if a collapse trigger were symmetric (which, as noted above, is highly unlikely), this is still not a sufficient “proof” that the subsequent dynamics of a collapse would proceed with such a high degree of symmetry and nearly to completion; a basic understanding of perturbation theory would lead a competently trained physical scientist to have serious doubts and reservations about such a claim.

It should also be pointed out (and I’ll leave it to other people or perhaps myself to follow up on this issue at another time) that the calculations made by Dr. Bazant in the first article (2002) do not appear to account for the core columns as contributing to the ability of the WTC Towers to withstand lateral forces during the observed tipping phase of the upper portion of the South Tower, and that he appears to discount entirely the core columns in the initial collapse phase when stating without a satisfactory amount of details:

“…the upper part may be assumed to move through distance h almost in a free fall...”

Indeed, is it a reasonable (and not clearly stated by Dr. Bazant) assumption that enough columns, perimeter and/or core, failed almost simultaneously so that an “almost” free fall motion of the upper part of the South Tower onto the lower part? This sort of assumption does not appear to be plausible based on the NIST computer simulations suggesting that 50 to 75 percent of the 47 core columns suffered no damage by the airplane impacts, and those that did suffer damage were graded from completely severed to light damage in four steps. And it is difficult to believe (a priori) that enough of the undamaged core columns plus those that were not severed would fail catastrophically all at the same time (or even nearly simultaneously) so as to not provide considerable resistance to an “almost” free fall drop of the upper portion onto the lower portion of either WTC Tower. And if the failures of the core columns were not nearly simultaneous and/or complete, what might the observed collapse sequence (dynamics) have been? Would a collapse sequence, if it were to happen at all, proceed with such a high degree of symmetry and nearly to completion?

And what exactly does it mean to “move almost in free fall?” There are perhaps too many such examples of vague qualifiers used in this first article (2002) by Dr. Bazant that require careful consideration: how much deviation from free fall of the upper portion of a WTC Tower onto the lower portion is required such that his simple analysis in the first article (2002) will not result in a progressive collapse based on the stated and implied assumptions and approximations?

Moving almost in free fall also brings up the issue of how fast the WTC Towers and WTC 7 collapsed with a high degree of symmetry nearly all the way to their foundations: is it reasonable to expect that such massive structures would collapse so quickly – basically in a free fall time interval – without the help of planted explosives? (Obviously, I’m quite doubtful that the answer to such a question would be in the affirmative.) This point of concern has been raised by many people and so there is little need for me to dwell on it here, except to point out that Dr. Bazant does not appear to be the least bit interested in this rather relevant observation and makes no attempt (meaningful or otherwise) to explain it in his simple models.

(A couple of other perhaps less relevant questions about the first article by Dr. Bazant (2002) might be: how did he decide on the choice of stiffness factor, C, used in his simplified modeling of the spring-like nature of the lower portion of the Towers, and why were such values not made available to him from an archived source of detailed information on these buildings? In fact it appears that throughout his analysis he had to use or calculate approximate values of the material properties, values that it seems reasonable to expect should be available from original blue prints and tests run during the design and construction of the WTC buildings.)

Furthermore, in the case of the WTC Towers and WTC 7 no attempt has been made by Dr. Bazant to reconcile the observed persistent hot spots in the debris field that were recorded in satellite spectra for several weeks after 9/11. It was later revealed during the removal of the debris field that the recorded hot spots were most likely the result of molten steel. How and why would there be molten steel in such a debris field several weeks after 9/11? Even if WTC 7 collapsed due to fires on the lower floors (as Dr Bazant has proposed in the addendum to the first article (2002)) that resulted from the prolonged burning of a liquid fuel (perhaps diesel fuel) on the day of 9/11, and perhaps had little to do with the damage suffered higher up in this building from falling debris from the WTC Towers, there are, of course, still symmetry considerations to take into account. Would these fires on the lower floors (or in the sub-structure) have been sufficiently hot and spread out to cause the observed nearly complete and relatively symmetric collapse of WTC 7? Furthermore, if such fires were raging on the lower floors, it seems reasonable to expect that the fire fighters would have noticed and made comments on them? And finally, it seems quite unlikely that such liquid fueled fires would result in what appears to be molten steel in the debris field for several weeks after 9/11. Of course, these questions of persistent hot spots and molten steel can be investigated further, both through real world experiments and computer simulations.

(We have read reports that the steel from the collapsed WTC buildings was shipped off, melted down, and turned into steel that was then used in the construction of a battle ship, and who knows what else. I can’t help but wonder if any of that steel was set aside and preserved in its original 9/11 collapse condition. I wonder what socio-political consequences might result if thorough tests were run on that steel confirming the use of demolition devices on 9/11?)

What about the explosions in the substructure of the WTC Towers many seconds before the impact of the airplanes? Dr. Bazant does not acknowledge these observations, both by eyewitnesses, and even more compellingly for a physical scientist, in the comparison of seismic records to the FAA flight data records. (What about the black boxes from the airplanes that would have contained an abundance of meaningful flight data?)

If building design and safety is of such paramount importance, as Dr. Bazant makes reference to in his articles, then why was the physical evidence contained in the debris field, evidence that might have helped to more accurately determine the nature and causes of the collapses, removed and destroyed with considerable efficiency and under relatively high security? Not once does Dr. Bazant appear to question or complain about this very obvious mistake of destroying valuable physical evidence. (And it does seem to be a curious situation that large computer simulations of the collapse dynamics have not been undertaken by other qualified people and discussed with a wider audience, at least with regard to building design and safety.)

In spite of the efforts of Dr. Bazant (and others such as NIST), it is abundantly clear to a good many qualified people that the official conspiracy story is highly unlikely and so the remaining evidence, physical and otherwise (including every last scrap of data at NIST), should be turned over to independent and honest groups of people for further investigations. Two questions then come to mind: Can such teams of investigators be formed and can the USA be compelled to turn over all of the remaining evidence?

(This article has been entirely written on my own without as yet any peer review, so any mistakes or omissions are entirely of my own doing, and I apologize in advance for any such blunders that may later be revealed.)


* ShineOn wishes to remain anonymous... for now. If you have a message for ShineOn, post it in the comments thread, and I'll make sure it is passed on. -r.

You crazy...


"So where is the oil going to come from?... The Middle East, with two-thirds of the world's oil and the lowest cost, is still where the prize ultimately lies."

Richard Cheney - Chief Executive Of Halliburton

Very nice

Comments are still open on the Bazant article - till November if I recall correctly. ShineOn on should submit a shorter version of this! I would suggest perhaps focusing on the assumptions of symmetric trigger and free fall in the initial stage, and leaving the alternative explosives hypothesis unstated.

I've read the actual paper

Hey everyone,

I'm currently finishing up post-graduate work in Mechanical Engineering, and had the chance to read the entire paper, as published in the journal.

As has already been explained, the most telling information lies in the introduction. It is laden with erroneous claims and references to dubious publications (as well as reference to NIST models, which have no been released. Anyone who works with FEM models knows that you could make the building fly if you tweaked the parameters the right way!)

The authors of this paper had decided to model a symmetric collapse due to a uniform load impact. They assumed the papers they referenced were correct and even say Bazant and Zhou (2002a) "PROVE" there was enough energy to take down the towers. They do not explain some of the models and parameters to my liking, but their analysis is interesting for its own sake. I haven't been too thorough in my reading, because I tend to always be in a rush.

Good post, nonetheless.

Still doesn't explain the hot-spots and newly found spheres of thermate residue.

For those interested, you would need liquid metal to be ejected in a gaseous explosion (i.e. thermate charges). The liquid metal cools in flight, while the surface tension of the ejected material causes the metal to form a perfect tiny little sphere. You can't form these spheres without high powered explosives.

Since you read it...

Do you remember if he tried to explain why the antenna (supported by the core) started to drop before the any other elements of the collapse were visible? Because this is the main thing that made NIST abandon the truss failure (pancake theory) for the column failure theory.

Also, to prove there was the necessary energy, they'd need to account for the energy required eject debris horizontally, pulverize almost all the non-concrete contents of the building to fine powder and break through all the lower floors without slowing down.

With all the talk about molten metal (which NIST and others) just claim wasn't there, I don't know why people don't point to the more damning "Deep mystery of the melting steel" that was proof of a euctectic reaction. This evidence was even included in FEMA's original report (Appendix C I think) and can't be ignored like the molten metal evidence.

There was no mention of the

There was no mention of the antenna. I just skimmed it.

How about this...

Thanks for the input,

I wondered about this quote, from the summary write-up above (not the actual report):: "Even if WTC 7 collapsed due to fires on the lower floors (as Dr Bazant has proposed in the addendum to the first article (2002)) that resulted from the prolonged burning of a liquid fuel (perhaps diesel fuel) on the day of 9/11..."

The fires were reportedly fed by the large quantity of diesel fuel stored near the building. How it got into the building seems like a rather large mystery to me, but that is not my question here.

Instead, it strikes me as odd that burning diesel fuel would be able to melt or even weaken steel. If it could, then diesel engines would all melt. Right?

even though they won't melt

expect this argument to be shot down by the fact that pretty much all combustion engines have a cooling system.

interns < internets

Good point

But inside the piston? I realize it is not an explosion in there exactly, but it surely gets up to burning temp?

BTW, I ask these questions naively, not being too well-versed in physics.

Inside the cylinder

there is an explosion, actually. Fuel is dispersed into aspirated air in stoichiometric (read: ideal) amounts in order to maximize its surface and thus reaction rate, and then explodes, driving the piston. As far as combustion in air goes, this delivers the optimum energy / time, i.e. power, attainable.

However, the limiting factor in air is mostly the inert nitrogen, making up ca. 80% volumetrically (gas molecules occupy the same amount of space regardless of mass and dependent only on ambient temperature and pressure). Some of the energy supplied by the fuel's oxidization is inevitably expended to heat the nitrogen "ballast", thereby dampening the temperature.

That's why you can perform really freaky things with liquid oxygen -- such as welding sheet metal with an oxygen soaked cigar -- and it's also why steel won't melt from atmospheric hydrocarbon fires, yet will melt in a blast furnace even though both might be supplied with the very same fuel. Apart from artificial oxygen supply, the air is also being pre-heated in furnaces to reduce its "heat sink" capacities.

Coming back to engines: As we all know, steel loses strength -- and expands -- when heated, and because especially the (uneven!) expansion would adversely affect an engine, it's being cooled.

I hope this info is of some use to you :-)

interns < internets

Interesting post...

...and relevant information, too.

You point out the obvious: "...steel won't melt from atmospheric hydrocarbon fires..."

How on earth can they support their own theories re: WTC fires.

How old is this?

Because even NIST doesn't support the progressive collpase theory. Is Dr. Bazant's piece claiming NIST is wrong? It's funny that the progressive collapse theory is so easily ruled out as possible just with video evidence alone that not even NIST will try and defend it yet people like Dr. Bazant and entities like the BBC still try to explain it. If they really believe that (they'd have to ignore a lot of the video evidence) then they should be calling for a new investigation.

I'm confused

Is "progressive collapse" synonymous with "pancaking"? I know NIST says it in its FAQ that it no longer believes the "pancake theory," but isn't its theory a kind of progressive collapse (or at least assumes that progressive collapse happened after the columns bowed in or whatever NIST says happened up to the point that "global collapse ensued.".)

Could someone explain this? Thank you.

And one other piece of evidence

Just look at the damn videos! Floor by floor it starts popping out! Use your eyes, Bazant!


Wow...this tool can't even

Wow...this tool can't even get the facts straight in his first sentence. "The destruction of the World Trade Center (WTC) on September 11, 2001 was not only the largest mass murder in U.S. history". I guess he fell asleep in high school history class when the trail of tears and other atrocities against our native population were discussed. Shame on you! Bigot! Native Americans ARE humans too!

"... In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual." (Galileo Galilei, 1564 - 1642)

thanks whitey

but our high school history classes still suck when it comes to the Native American holocaust, among many other distorted and/or taboo subjects.
if only Native Americans could get an entire hour of CBS' 'the amazing race' devoted to the genocide that occurred on our own soil...
"Whoever fights monsters should see to it that in the process he does not become a monster. And when you look long into an abyss, the abyss also looks into you."Friedrich Nietzsche, Beyond Good and Evil 89 (1886).

Woefully Inconclusive

This post struck me as very questionable. E.g., Bazant is criticized for not trying to explain the symmetry of the collapses, but that was not his purpose. Therefore, such criticism amounts to a strawman.*

Another problem with it is that it mixes up criticisms that at least attempt to be technically-oriented, with criticism of the Bazant-Verdure paper as propaganda. This is sure to turn off structural engineers from taking a cold, hard look at the Bazant Zhou paper, and it's descendents. Does the author even care about this?

Finally, what was the author thinking when penning such provocative statements as "It is also quite reasonable for us to expect an honest and ethical discussion (or analysis) by Dr. Bazant to have at least questioned or complained about the lack of completeness and transparency in presentation (that might properly be considered a foundation principal of the “scientific method”) on the part of NIST in not releasing all of the details of their computer simulations, even though these (supposedly) only deal with the lead-up to the collapse (initiation) trigger" ?

I'm very suspicious of NIST, myself, but apparently Dr. Bazant is not. Furthermore, even if Dr. Bazant is also suspicious of NIST, should he give voice to any such suspicions in a technical paper? The presumption in the engineering community is that other engineers will do their jobs. Even if an engineer holds personal doubts about another's work, they are likely to be suppressed. Such a tendency is in no way peculiar.

Regardless of what the answers to these speculative questions are, at the end of the day, Professor Bazant is only answerable for his own works. This post muddies the technical waters with conspiracy theory considerations and innuendo.

Thus, as somebody who has made efforts to get serious scientists and engineers to critically examine the Bazant Zhou paper, I find this post somewhat upsetting. But I can offer the following.

The Bazant Zhou paper makes energy dissipation calculations with no reference to the literature on dynamic impacts. And yet, engineers were studying impacts on (besides other structures) tall, thin metal plates since at least 1984. Another paper has studied impacts on thin, hollow square rods (more similar to WTC box columns). Indeed, there's even a journal (or two...) dedicated to impacts. Instead, Bazant Zhou compute energy dissipation as though it occurred in a quasi-static manner, even though their assumption of an initial collapse of 1 storey height would give an initial impact velocity of about 8 m/s. In other words, their own assumption clearly implies that they are working in a dynamic regime.

What is the problem with this? From the summary of the Calladine and English paper, we can see how likely this is to be wrong:

The dynamic collapse of energy-absorbing structures is more difficult to understand than the corresponding quasi-static collapse, on account of two effects which may be described as the "strain-rate factor" and the "inertia factor" respectively. The first of these is a material property whereby the yield stress is raised, while the second can affect the collapse mode, etc. It has recently been discovered that structures whose load-deflection curve falls sharply after an initial "peak" are much more "velocity sensitive" than structures whose load-deflection curve is "flat-topped"; that is, when a given amount of energy is delivered by a moving mass, the final deflection depends more strongly on the impact velocity. In this paper we investigate strain-rate and inertia effects in these two types of structure by means of some simple experiments performed in a "drop hammer" testing machine, together with some simple analysis which enables us to give a satisfactory account of the experimental observations. The work is motivated partly by difficulties which occur in small-scale model testing of energy-absorbing structures, on account of the fact that the "strain-rate" and "inertia" factors not only scale differently in general, but also affect the two destinct types of structure differently.

Calladine, C. R. and English, R. W., "Strain-rate and Inertia Effects in the Collapse of Two Types of Energy-Absorbing Structure", Int. J. Mech. Sci., Vol. 26, No. 11/12, pp. 689-701, 1984.

An impacting velocity of about 8 meters/second (as posited in BZ) is just outside the regime tested experimentally by Calladine and English. In Calladine and English's work, none of the metal samples broke. Instead, all of them fully absorbed the effects of the vertical blow, with various degrees of bending. In the trial most similar to the Bazant Zhou scenario, an impacting mass equal to 71x the weight of the apparatus being impacted was dropped from a height of 2.74 meters, or 72% the height of one WTC story.

There are many simplyfying assumptions in the Bazant Zhou paper (and Bazant Verdure), some of them favorable to collapse, and some of them unfavorable. Therefore, it's not clear to me what their paper COULD possibly prove, unless some sort of quantitative statements regarding bounding the effects of various assumptions can be made. (E.g., "ignoring dynamic effects has made non-global collapse only X% less likely, and will speed up the collapse by at most Y% seconds")

IMO, it would have been better for them to only make assumptions that favored collapse, and then showed that global collapse would not occur, anyway. OR, they could have made assumptions all unfavorable to collapse, and then showed that global collapse would occur, anyway.

As it is, they have left us with a very muddled picture, from which no logical conclusions regarding the real-life WTC collapses can be made, and it's disconcerting to me that the $20 million dollar NIST report would reference such an inadequate work as justification for not studying post-collapse-initiation.

I look forward to some qualified structural engineer, civil engineer, mechanical engineer, or physicist applying scaling rules gleaned from impact studies, such as that of Calladine and English, to a specific scenario compatible with that of the Bazant Zhou paper. I believe that making corrections for dynamic effects will result in a conclusion similar to that of the Gordon Ross paper, posted on the Journal of 911 Studies web site ( , whose approach sought to model some dynamic effects beyond that of Bazant Zhou.

Even if making corrections along these lines to the Bazant Zhou paper shows that global collapse would not have ensued, that will not be the end of the story. As pointed out by Bazant and Zhou, the assumption of a symmetric collapse and axial strike is favorable for survival. Correcting the corrections would involve figuring out the effects of non-symmetry, as well as other factors such as fracturing, splice failure, falling mass outside the footprint, concrete pulverisation etc.

Personally, I am very pessimistic that even serious attempts to model all of the factors mentioned above, in a simplified approach, will be tractable. At the end of the day, I don't see how anything akin to "proof" of global collapse - or it's contrary - can be attained without computer modelling. Which is something that NIST was particularly well positioned to carry out.

There is an effort underway amongst the Scholars for 911 Truth and Justice ( ) to construct a computer model of collapse. May I suggest that interested, qualified individuals who may be interested in assisting, do so?

Some more references which I dug up recently (but havent' read) follow this post. See also the paper by physicist Charles M. Beck

* I have not read his latest paper, but the Bazant Zhou paper assumes symmetry, and does not try to explain it.

More references on dynamic impacts

Note: I discovered the following a couple of days ago, and haven't read them. My apologies if some turn out to be irrelevant.

I found these using

Dynamic Axial Crushing of Square Tubes
Abramowicz, W; Jones, N
Int. J. Impact Eng. Vol. 2, no. 2, pp. 179-208. 1984

Eighty-four dynamic tests on thin-walled square steel tubes having two different cross-sections with c/h = 30.25 and c/h = 32.18 and various

lengths were crushed axially on a drop hammer rig. Approximate theoretical predictions were developed for the axial progressive crushing of

square box columns using a kinematically admissible method of analysis. This theoretical study predicts four deformation modes which govern

the behavior for different ranges of the parameter c/h. New asymmetric deformation modes were predicted theoretically and confirmed in the

experimental tests. These asymmetric modes cause an inclination of a column which could lead to collapse in the sense of Euler, even for

relatively short columns. The effective crushing distance is considered in the approx. theoretical analysis together with the influence of

material strain rate sensitivity, which is important for steel even when the loadings are quasistatic. The simple equations presented for the

design of axially crushed square box columns give reasonable agreement with the corresponding experimental results. 30 ref.--AA



Finite element investigations on the dynamic plastic buckling of a slender beam subject to axial impact
Authors: Kenny S.; Pegg N.; Taheri F.1
Source: International Journal of Impact Engineering, Volume 27, Number 2, February 2002, pp. 179-195(17)


Inertia effects in axisymmetrically deformed cylindrical shells under axial impact
Authors: Karagiozova D.; Alves M.; Jones N.

Experimental and theoretical studies of columns under axial impact.
Ari-Gur, J; Weller, T; Singer, J
INT. J. SOL. & STRUCT. Vol. 18, no. 7, pp. 619-641. 1982

The dynamic response of columns loaded by an impulsive axial compression is studied experimentally and theoretically. Approximate criteria

for determination of dynamic buckling are discussed and applied. The investigation was carried out on clamped specimens, made of metals and

composite materials, loaded impulsively by a striking mass. In the theoretical study, Rayleigh-type beam equations are assumed for a

geometrically imperfect column of a linear-elastic anisotropic material. A numerical solution, by means of a finite-difference approach,

yields buckling behavior which correlates well with the experimental results. It is shown that initial geometrical imperfection, duration of

impulse, and effective slenderness have a major influence on the buckling loads, whereas the effect of the material is secondary. The major

effects are presented in a form that can guide the designer.

Dynamic Progressive Buckling of Square Tubes
Chih-Cheng Yang



Inertia and Strain-Rate Effects in a Simple Plate-Structure Under Impact Loading
Tam, L L; Calladine, C R
International Journal of Impact Engineering (UK). Vol. 11, no. 3, pp. 349-377. 1991

Previous studies have shown that the way in which metal structures absorb energy by gross distortion under impact conditions depends on the generic type of structure. In particular, they have shown that structures which respond to quasi-static testing by means of an initial peak load followed by a falling load as deformation proceeds ("type II" response, corresponding broadly to plates loaded endwise) exhibit both inertia and strain-rate effects under impact loading from moving strikers. A detailed study of these phenomena by means of experiment and theory is described. Experiments were conducted in a drop-hammer rig on a large number of specimens having the same general geometry, but made in two different sizes and of two different materials (mild steel, Al alloy) chosen for their different strain-rate characteristics in the plastic range. The experiments involved the overall measurement of final distortion of the specimens in relation to a wide range of testing conditions with moderate velocity; strain gauge studies, high-speed photography and other investigations of the detailed behaviour. The main emphasis of the various assays was to discover the way in which the initial kinetic energy of the striker was dissipated within the structure. During the course of the work, Zhang and Yu proposed a simple analysis of the same phenomena by means of a model based on the ideas of classical inelastic impact theory. According to their theory, a significant fraction of the incident kinetic energy of the striker is absorbed during the initial impact event; and this fraction depends only on the ratio of the mass of the striker to the mass of the specimen and the initial crookedness, but not on the velocity of impact. Here, the experiments agreed with this analysis in some overall respects, but were irreconcilable with it in several others, for which substantial data had been amassed. Therefore, a revised analysis was produced, which was less austere than that of Zhang and Yu but which nevertheless remained essentially simple. It is shown that this new theory agrees satisfactorily with all aspects of the experimental observations. The analysis reveals clearly the roles of inertia and strain rate in impact conditions. It also produces two new dimensionless groups, which together provide a key to classification of the various patterns of behaviour which are possible in the impact response of "type II" specimens.

The influence of inertia and strain-rate on large deformation of plate-structures under impact loading.
Webb, D. C.; Kormi, K.; Al-Hassani, S. T. S.
Computers & Structures. Vol. 79, no. 19, pp. 1781-1797. July 2001

The static and dynamic behaviour of plate-structures subjected to in-plane axial and compressive impact loading is investigated using the finite element method (FEM). The material model is linear elastic with nonlinear isotropic work hardening characteristics with strain-rate dependence, inertia (via a consistent mass matrix) and geometrical nonlinearities are retained. The FEM results are in very close agreement with those obtained from experiments but the main advantage of the method is that it clarifies the time history behaviour of the model. The previous theoretical work has identified two distinct phases of deformation. Phase one is the compression of the plate, following the inelastic collision, until the structure becomes plastic. This is followed by a second phase of continuous plastic work dissipation in rotation about the hinges formed. The FEM results indicate the nature of the collision strain rate intensity and the differences that exist between static and dynamic modes of deformation response. The numerical modelling also reveals four phases in the deformation process. A phase of stress wave propagation is identified during elastic loading and the build up of high initial axial forces in the specimen. This is followed by a squashing phase, hinge rotation and elastic recovery (or, when the impact energy is high enough, structural closure) before the striker rebounds. The closure phase resembles a severe forming process followed by elastic recovery of the specimen and rebound of the striker. The differences between the various treatments are discussed and analysed in some detail.


A note on the inertia and strain-rate effects in the Tam and Calladine model


Impact failure of beams using damage mechanics: Part I-Analytical model

Axial crushing of square tubes.
Meng, Q.; Al-Hassani, S. T. S.; Soden, P. D.
International Journal of Mechanical Sciences. Vol. 25 no.9/10, no. 1983, pp. 747-73. 1983



Scaling impacted structures when the prototype and the model are made of different materials



Dynamic buckling of elastic-plastic beams including effects of axial stress waves
Author: Lepik U.

Their assumptions are so unrealistic


I can see the benefit of showing through a computer model that even under their assumptions, the buildings would not collapse.

However, the symmetry assumption is unrealistic, as Bazant Zhou admit, and the free fall impact velocity is absurd, as they do not admit. Symmetrical free fall impact seems all the more unlikely.

I am concerned that your call for a computer model puts an unrealistic burden on scientists with less resources, and gets us into competing models which would in the end be resolved by questioning assumptions, anyway. Why not focus on the unrealistic assumptions to begin with? Then, as you show, it can be argued that even under this unrealistic assumption the building should not have collapsed.

I agree that the conspiracy stuff does not help reach scientist and engineers.

Thank you for the references and explanations.

I am not an engineer or physicist.

but you do make a lot of sense

unless you're talking no planes. Needed to be said.

interns < internets

What is "survival"?

As pointed out by Bazant and Zhou, the assumption of a symmetric collapse and axial strike is favorable for survival.

But they say symmetric collapse is unlikely. And what does "survival" mean? No collapse of any kind? Or does it mean no buckling of the particular columns or sections of the building that were impacted? If symmetric impact is not assumed, would the building have "collapsed" as observed?

Reading again, I see you say that you are not confident that a model can prove or disprove NIST, because the problem is so complex. Is it feasible for Scholars for 9/11 Truth and Justice to model this? Wouldn't it be better to attack the key assumptions of initial free fall and symmetry? Greening has stated that his free fall assumption was wrong.

Not only is a symmetric

Not only is a symmetric collapse unlikely, it didn't happen that way. There were tilts in both WTC towers.

However, assuming a symmetric collapse vastly simplifies your computational problem. That is completely understandable. It's one thing to write down a bunch of equations that you believe describes a system. It's another thing to solve them, even if they're "well posed". The logical flaw is to assume that just because you've come up with an easily sovable model, that it's essential conclusion must be correct. Absent serious and comprehensive arguments to this end, why should anybody accept this?

"Survival" means that only a local collapse occurred. However, in terms of determining whether the building was deliberately demolished, it could also be taken as meaning that the building should have collapsed more slowy and/or less completely (e.g.., a defintive analysis my show the perimter and truss-areas to collapse, but not all of the core) to not be controlled demolition.

I was less concerned about "disproving NIST", per se, than about disproving Bazant Zhou, which NIST cites as justification for their aborted analysis. Since NIST is not sharing whatever work they have done on post-collapse initiation, how can they be disproven? By mind reading?

What I am skeptical of is that any "simple" model - even models considerably more complicated and realistic than Bazant Zhou's - which are still simple enough to be tractable without considerable FEA analysis included, would settle the matter. Whether the work being undertaken at Scholars for 911 Truth and Justice, whatever it's conclusions, is sufficient to convince most engineers, is not for me to say. I'm not an engineer!

As for "attacking the key assumptions of initial free fall and symmetry", the desired goal is not simply to criticize and then wave one's hands and say "so they've probably come to exactly the wrong conclusion". The point is to criticize with an eye to getting better models that one can have faith in. If one does not have the skills (as I do not), one must hope that better qualified individuals come along and do the work that one is trying to facilitate. For some reason or another, it seems too HARD for the US government to fund such a study, though it's got no problem wasting hundreds of billions of dollars in Iraq.

The Physics

The Physics

All of the collapse hypotheses that support the official story are "Gravity Only" hypothesis i.e. they all state that, in the case of the towers, the energy needed to destroy the buildings is derived solely from the kinetic energy of a falling block of floors.
None of these hypotheses adequately examine the collapses with reference to the Laws of Conservation of Energy or Momentum.

It is possible however, to measure the the distance the block of floors has fallen in a given time, and from these data it is a relatively straight forward calculation to quantify the energy that the falling block is contributing to the destruction of the lower floors.

Once this destructive energy is quantified it is very easy to conclude that these events are not driven by gravity alone.

My own measurements for WTC1 for example, show that :- after the first 7.4 meters of the fall, the block of floors is accelerating at 9.6 ms-2 (free fall in a vacuum is 9.8 ms-2) meaning that the energy supplied to the destruction of 2 floors that represent a mass of over 9.2 million kilos is 1.8MJ.
1.8MJ is enough energy to lift 9.2 million kilos less than 1 inch off the ground.

Don't take my word for it! you can do these measurements yourselves.

Here is one method

Here is some data collected by some one else.
This from Mon 17th September 2001

Here is some software
(Logger Pro 3 {30 day trial})

Logger Pro 3 can collect data from video and work out velocities accelerations etc. This software requires that you input the scale from the video and makes no allowances for foreshortening effects. I think Greening used something like this to support his collapse hypothesis, but I've checked his observations against my own and the above from Glenn Carlson and Greenings' observed values appear to be erroneous, probably due to errors in setting the scale.

Using (the appropriately named) Law of Conservation of Energy in this way shows that ANY "Gravity Only" hypothesis is doomed from the start.