Loose Change - Part IV

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Guys;

Over at the SLC Forum, a poster with UN=SeeOtter has brought up a point that I do not have clarification, on but I think needs some.

NIST, in their FAQ, state that the NIST findings do not support the "pancake" theory of collapse.

Yet, the PM book on debunking 9/11 Myths, on page 44, says that the buildings collapsed in what engineers describe as pancaking.

[... snip ...]
NIST's findings do not support the "pancake theory" of collapse, which is premised on a progressive failure of the floor systems in the WTC towers (the composite floor system--that connected the core columns and the perimeter columns--consisted of a grid of steel "trusses" integrated with a concrete slab; see diagram below). Instead, the NIST investigation showed conclusively that the failure of the inwardly bowed perimeter columns initiated collapse and that the occurrence of this inward bowing required the sagging floors to remain connected to the columns and pull the columns inwards. Thus, the floors did not fail progressively to cause a pancaking phenomenon.
[... snip ...]

Popular Mechanics 'Debunking 9/11 Myths', p. 44:
[... snip ...]
"Once each tower began to collapse, the weight of all the floors above the collapsed zone bore down with pulverizing force on the highest intact floor. Unable to absorb the massive energy, the floor failed, transmitting the forces to the floor below, allowing the collapse to progress downward through the building in a chain reaction. Engineers call the process pancaking
[... snip ...]
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Any clarification would be helpful.

TAM
 
T.A.M. said:
Guys;

Over at the SLC Forum, a poster with UN=SeeOtter has brought up a point that I do not have clarification, on but I think needs some.

NIST, in their FAQ, state that the NIST findings do not support the "pancake" theory of collapse.

Yet, the PM book on debunking 9/11 Myths, on page 44, says that the buildings collapsed in what engineers describe as pancaking.



Any clarification would be helpful.

TAM
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I think it is the difference between the initiation of the collapse, and what occurred after the collapse was underway.
 
The commission report mentions pancaking as well (p308 in the PDF, and only in a sentence like "they ran, as the tower began its pancake collapse").
 
Arkan_Wolfshade said:
I think it is the difference between the initiation of the collapse, and what occurred after the collapse was underway.
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So initially, it was pancaking, and turned into the floors failing inwards(sorry if my details, or even interpretation, are shoddy, but I haven't read up on my WTC that much)?
 
The FAQ:
NIST’s findings do not support the “pancake theory” of collapse, which is premised on a progressive failure of the floor systems in the WTC towers (the composite floor system—that connected the core columns and the perimeter columns—consisted of a grid of steel “trusses” integrated with a concrete slab; see diagram below). Instead, the NIST investigation showed conclusively that the failure of the inwardly bowed perimeter columns initiated collapse and that the occurrence of this inward bowing required the sagging floors to remain connected to the columns and pull the columns inwards. Thus, the floors did not fail progressively to cause a pancaking phenomenon.
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Arkan:

My memory is the same as yours, and I stated this to him, but it is from memory of discussion here only. I cannot remember the source for this...any ideas?
 
I noticed that on the LC forum lately, we have become a kind of boogey man to them. Some are using the "JREF" name like Joe McCarthy used "communist" in the 50's, to ruin a persons credibility.

"He has the JREFers support."
 
T.A.M. said:
Guys;

Over at the SLC Forum, a poster with UN=SeeOtter has brought up a point that I do not have clarification, on but I think needs some.

NIST, in their FAQ, state that the NIST findings do not support the "pancake" theory of collapse.

Yet, the PM book on debunking 9/11 Myths, on page 44, says that the buildings collapsed in what engineers describe as pancaking.

Any clarification would be helpful.

TAM
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Hmm, I just saw a similar question in another thread. I guess you guys read the same things elsewhere in the 'net. My answer is here.

As for why the Popular Mechanics book uses the slighly incorrect pancaking term, I can only assume it's a basic error. Perhaps they went to press before NIST made their clarification, or they didn't appreciate the difference. It's a subtle distinction.
 
T.A.M. said:
Arkan:

My memory is the same as yours, and I stated this to him, but it is from memory of discussion here only. I cannot remember the source for this...any ideas?
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Home now, here is the full quote from the PM book
Several studies, most notably those by FEMA and NIST, determined that the towers fell as a result of fires that weakened the supporting steel columns near the point of the plane impacts. The fires themselves likely would not have brought down the towers, but in combination with the damage from the crashes they proved fatal. Once each tower began to collapse, the weight of all the floors above the collapsed zone bore down with pulverizing force on the highest impact floor. Unable to absorb the massive energy, that floor failed, transmitting the forces to the floor below, allowing the collapse to progress downward through the building in a chain reaction. Engineers call the process pancaking, and it does not require an explosion to being, according to David Biggs, a structural engineer at Troy, New York-based Ryan-Biggs Associates and a member of the American Society of Civil Engineers (ASCE) team that worked on the FEMA report
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The only mention of "pancake" from the FEMA report says
As the temperature of floor slabs and support framing increases, these elements can lose rigidity and sag into catenary action. As catenary action progresses, horizontal framing elements and floor slabs become tensile elements, which can cause failure of end connections (Figure 2-21) and allow supported floors to collapse onto the floors below. The presence of large amounts of debris on some floors of WTC 1 would have made them even more susceptible to this behavior. In addition to overloading the floors below, and potentially resulting in a pancake-type collapse of successive floors, local floor collapse would also immediately increase the laterally unsupported length of columns,
permitting buckling to begin. As indicated in Appendix B, the propensity of exterior columns to buckle would have been governed by the relatively weak bolted column splices between the vertically stacked prefabricated exterior wall units. This effect would be even more likely to occur in a fire that
involves several adjacent floor levels simultaneously, because the columns could effectively lose lateral support over several stories (Figure 2-22).
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The 9/11 Commission report returns not hits for "pancak" (used to catch both pancake and pancaking")

Now, keep in mind, the FEMA report was released early '02 iirc, whereas the NIST FAQ the person is quoting is from '06 which states
Based on this comprehensive investigation, NIST concluded that the WTC towers collapsed because: (1) the impact of the planes severed and damaged support columns, dislodged fireproofing insulation coating the steel floor trusses and steel columns, and widely dispersed jet fuel over multiple floors; and (2) the subsequent unusually large jet-fuel ignited multi-floor fires (which reached temperatures as high as 1,000 degrees Celsius) significantly weakened the floors and columns with dislodged fireproofing to the point where floors sagged and pulled inward on the perimeter columns. This led to the inward bowing of the perimeter columns and failure of the south face of WTC 1 and the east face of WTC 2, initiating the collapse of each of the towers. Both photographic and video evidence—as well as accounts from the New York Police Department aviation unit during a half-hour period prior to collapse—support this sequence for each tower.

NIST’s findings do not support the “pancake theory” of collapse, which is premised on a progressive failure of the floor systems in the WTC towers (the composite floor system—that connected the core columns and the perimeter columns—consisted of a grid of steel “trusses” integrated with a concrete slab; see diagram below). Instead, the NIST investigation showed conclusively that the failure of the inwardly bowed perimeter columns initiated collapse and that the occurrence of this inward bowing required the sagging floors to remain connected to the columns and pull the columns inwards. Thus, the floors did not fail progressively to cause a pancaking phenomenon.
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Not to be nitpicking, but still- the commission report does mention pankcaking- at least my paperback version and the pdf version I looked at yesterday (where it was at page 308- that's the printed number on the page, not the actual pdf page, which is 325).
 
I think that the confusion (if that's what it is) stems from an unfortunate overlap in terminology - the "engineering" use of the term "pancaking" and the "layman" use of the word "pancaking" - combined with the distinction between the initiation of the collapse and the collapse itself.
 
LashL said:
I think that the confusion (if that's what it is) stems from an unfortunate overlap in terminology - the "engineering" use of the term "pancaking" and the "layman" use of the word "pancaking" - combined with the distinction between the initiation of the collapse and the collapse itself.
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So they weren't a stack of fried batter patties covered in syrup and butter? Well that explains some of my confusion.
:)
 
CptColumbo said:
So they weren't a stack of fried batter patties covered in syrup and butter? Well that explains some of my confusion.
:)
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Some of your confusion might also stem from ignoring the fact that there was also a bunny involved. :)

:bunpan

(It's true!)
 
CptColumbo said:
LOL<--you get the first two, but that's it.
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Two in a row ~ Ill take it. :)


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<ponders the quasi-gauntlet just the same, and will work on number 3 another day... when you least expect it :) >
 
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