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Analysis of Bazant & Zhou (2002)

bofors

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bofors
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As the NIST report rests on the Bazant & Zhou (2002) is the place to start in taking apart the official theory of "collapse" in WTC twin tower on 9/11.

The paper is here: http://www.civil.northwestern.edu/people/bazant/PDFs/Papers/405.pdf

Point 1 This paper was "rapid communication". It actually appears to have been only written in less that two days, published on 9/13/01: http://web.archive.org/web/20011031095744/http://www.tam.uiuc.edu/news/200109wtc/

So,

Point 1.1 Bazant & Zhou (2002) was not carefully crafted and well thought out, but something hastily thrown together in a matter of hours.

Point 1.2 Bazant & Zhou (2002) was not subject to a normal peer review process and probably received no peer review at all.
 
Point 2 Bazant and Zhou were forced to include an "Addendum" (pages 6-7) which answers six questions about the paper from skeptics in the structural engineering community. This appears to be the only "peer review" the paper received.

From points 1 & 2, we can conclude that this paper should not be described as being "peer reviewed" as the evidence indicates that it was not. This is obviously a low quality paper on its face.
 
bofors said:
Point 2 Bazant and Zhou were forced to include an "Addendum" (pages 6-7) which answers six questions about the paper from skeptics in the structural engineering community. This appears to be the only "peer review" the paper received.

From points 1 & 2, we can conclude that this paper should not be described as being "peer reviewed" as the evidence indicates that it was not. This is obviously a low quality paper on its face.
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Wrong. Please do not make big errors like this. Please try again. This is such a sad error; what Journal did their paper appear (this is the big hint)?

The question is; what Journal was their paper published in? The answer makes your Claim false. So did you ask the authors about your claims? Are you making this up as you go, or did you really read the paper? Wait, you have not read the paper; why?
 
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Given you have told us that you have read the paper, please provide your analysis of it. I know that if you are to have ANY degree of scientific legitimacy behind you, that your above points are not the summation of your review.

Point 1.1 Bazant & Zhou (2002) was not carefully crafted and well thought out, but something hastily thrown together in a matter of hours.

Point 1.2 Bazant & Zhou (2002) was not subject to a normal peer review process and probably received no peer review at all.
Click to expand...

if the above was submitted to ANY JOURNAL as a critique, or even just a commentary, YOU WOULD BE LAUGHED AT by your peers and by the engineering community.

Now...

A point by point critique of this paper, which you have claimed to have read, would be sufficient. Please begin.

TAM:)
 
Also of note was its REPUBLICATION, found here,

WHY DID THE WORLD TRADE CENTER COLLAPSE?—SIMPLE ANALYSIS
PB ZDENĚK - International Journal of Structural Stability and Dynamics, 2001

With the added note, the abstract states...

This paper [note: The original version with Eqs. (1) and (2) was originally submitted to ASCE on September 13, and an expanded version with Eq. (3) was submitted to ASCE on September 22. Appendix II was added on September 28, and I and III on October 5. The basic points of this paper, submitted to SIAM, M.I.T., on September 14, were presented in Refs. 5 and 6. A report on which this paper is based on was posted with updates since September 14 at http://wwww.civil.northwestern.edu/news, http://www3.tam.uiuc.edu/news/200109wtc/, and http://math.mit.edu/~bazant] 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. Despite optimistic simplifying assumptions, the structural resistance is found to be an order of magnitude less than necessary for survival.
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Google Scholar is your best friend...

TAM:)
 
It is certainly a real sad fact that these points have to be mentioned to you Bofors, who are you trying to fool here?
 
Does it bother you, Bofors, that your Point 2 negates your Point 1.2?

Probably as much as your Point 1.1 being a premise that you have failed to establish at all.
 
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.

Point 3 In their abstract, Bazant & Zhou claim they only provide a "simplified approximate" analysis here, so in no way does this paper represent anything approaching precise and thorough explanation for the "collapse" of the WTC buildings. NIST deliberately committed a grave error by simply defering the very serious question of "gobal collapse" mechanism to this paper.

Point 4 Bazant & Zhou assume "prolonged heating" initiated the "collapse" of the twin towers, but despite providing five multi-part figures they show no Time-Temperate Curves as neccessary to understand the behavior of steel in fires: http://en.wikipedia.org/wiki/Fire-resistance_rating Furthermore, Bazant & Zhou fail to mention any Time-Temperate Curve data in paper what-so-ever. From the lack of Time-Temperate Curves or data it is hard to understand how Bazant & Zhou could have provided any model for "collapse" stemming from "prolonged heating".

Point 5 Bazant & Zhou claim that a "majority" of columns need to "lose their load carrying capacity" on a single floor to ensure "total collapse", however the authors fail to provide any equation to support this assertation. In fact, of the eight equations explicitly listed, none even use the number of columns (failed or otherwise) as a variable. Furthermore, no where in the paper do Bazant & Zhou even attempt to explain why a simple "majority" of columns are needed to fail in order for "global collapse" to ensue.

Point 6 Bazant & Zhou claim that columns "lose their load carrying capacity", but no where in the paper do the authors even attempt to show which columns are supposed to have done so. Moreover, since Bazant & Zhou explictly ignore the possibility of column facture, all columns should obviously retain some "load carrying capacity".
 
What's even more embarrassing is that his "analysis" isn't even original. He's cribbing off of Hoffman.
 
bofors said:
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.

Point 3 In their abstract, Bazant & Zhou claim they only provide a "simplified approximate" analysis here, so in no way does this paper represent anything approaching precise and thorough explanation for the "collapse" of the WTC buildings. NIST deliberately committed a grave error by simply defering the very serious question of "gobal collapse" mechanism to this paper.

Point 4 Bazant & Zhou assume "prolonged heating" initiated the "collapse" of the twin towers, but despite providing five multi-part figures they show no Time-Temperate Curves as neccessary to understand the behavior of steel in fires: http://en.wikipedia.org/wiki/Fire-resistance_rating Furthermore, Bazant & Zhou fail to mention any Time-Temperate Curve data in paper what-so-ever. From the lack of Time-Temperate Curves or data it is hard to understand how Bazant & Zhou could have provided any model for "collapse" stemming from "prolonged heating".

Point 5 Bazant & Zhou claim that a "majority" of columns need to "lose their load carrying capacity" on a single floor to ensure "total collapse", however the authors fail to provide any equation to support this assertation. In fact, of the eight equations explicitly listed, none even use the number of columns (failed or otherwise) as a variable. Furthermore, no where in the paper do Bazant & Zhou even attempt to explain why a simple "majority" of columns are needed to fail in order for "global collapse" to ensue.

Point 6 Bazant & Zhou claim that columns "lose their load carrying capacity", but no where in the paper do the authors even attempt to show which columns are supposed to have done so. Moreover, since Bazant & Zhou explictly ignore the possibility of column facture, all columns should obviously retain some "load carrying capacity".
Click to expand...

Well this is at least a start.

TAM:)
 
bofors said:
Point 3 In their abstract, Bazant & Zhou claim they only provide a "simplified approximate" analysis here, so in no way does this paper represent anything approaching precise and thorough explanation for the "collapse" of the WTC buildings. NIST deliberately committed a grave error by simply defering the very serious question of "gobal collapse" mechanism to this paper.
Click to expand...

It dosn't need to be perfectly precise. And can't really be by nature.

Point 4 Bazant & Zhou assume "prolonged heating" initiated the "collapse" of the twin towers, but despite providing five multi-part figures they show no Time-Temperate Curves as neccessary to understand the behavior of steel in fires: http://en.wikipedia.org/wiki/Fire-resistance_rating Furthermore, Bazant & Zhou fail to mention any Time-Temperate Curve data in paper what-so-ever. From the lack of Time-Temperate Curves or data it is hard to understand how Bazant & Zhou could have provided any model for "collapse" stemming from "prolonged heating".

Point 5 Bazant & Zhou claim that a "majority" of columns need to "lose their load carrying capacity" on a single floor to ensure "total collapse", however the authors fail to provide any equation to support this assertation. In fact, of the eight equations explicitly listed, none even use the number of columns (failed or otherwise) as a variable. Furthermore, no where in the paper do Bazant & Zhou even attempt to explain why a simple "majority" of columns are needed to fail in order for "global collapse" to ensue.
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This seems to be common sense: for a collapse, you need failure of a column.. to make it global..

Point 6 Bazant & Zhou claim that columns "lose their load carrying capacity", but no where in the paper do the authors even attempt to show which columns are supposed to have done so. Moreover, since Bazant & Zhou explictly ignore the possibility of column facture, all columns should obviously retain some "load carrying capacity".
Click to expand...

Steel when warm does what?
 
bofors said:
Page 1, Paragraph 1:

Introduction and Failure Scenario
The 110-story towers of the World Trade Center were designed to
withstand as a whole the forces caused by a horizontal impact of
a large commercial aircraft
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707, low fuel, low speed, lost in the fog - 187 pounds of TNT energy at impact (not many people in the world understand this; ask the chief engineer of the WTC about this design)

flight 11, high speed, high fuel, on purpose - 1300 pounds of TNT energy at impact

flight 175, high speed, high fuel, on purpose - 2066 pounds of TNT energy at impact

Your point is lost!
 
bofors said:
Page 1, Paragraph 1:

Introduction and Failure Scenario
The 110-story towers of the World Trade Center were designed to
withstand as a whole the forces caused by a horizontal impact of
a large commercial aircraft
Click to expand...


and both towers did so, for at least 50 minutes.

TAM:)
 
notice how bofors has ignored the replies..he can't think for himself so he steals it from those who "wrote" before him
 
Page 1, Paragraph 1:

So why did a total collapse occur? The cause was the dynamic consequence of the prolonged heating of the steel columns to very high temperature. The heating lowered the yield strength and caused viscoplastic creep buckling of the columns of the framed tube along the perimeter of the tower and of the columns in the building core. The likely scenario of failure is approximately as follows.

Point 7 Bazant & Zhou claim that heating lowered the yield strength of the column materials, but no where do they provide any numerical estimates of any yield strength.

Point 8 Bazant & Zhou claim viscoelastic creep lead to buckling, however they provide no equations for creep, nor do they discuss creep further in the paper. Moreover, the authors fail to explain the relationship between creep and yield strength.

Point 9 Bazant & Zhou claim a "likely scenario of failure" but provide absolutely no estimates of probability for any failure scenarios, nor do they even bother to consider other possible failure scenarios.
 
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