Collapse dynamics: Matthys Levy on controlled demolition [View All]

[plaguepuppy]

Some interesting comments from the author of Why Buildings Fall Down (http://www.amazon.com/exec/obidos/ASIN/039331152X/ref=pd_ecc_rvi_4/102-0245915-6264177)

http://www.plaguepuppy.net/public_html/video%20archive/discovery.wmv


Levy is also one of the authors of the study done by Weidlinger Associates for Larry Silverstein:
http://enr.construction.com/news/buildings/archives/021025.asp



"The report exonerates the floor trusses for the collapses. "Failure of the floors...was shown not to have had any significant role in the initiation of the collapses," it says. Studies by Hughes Associates and ARUPFire led the team to conclude that tower floors survived the initial impact of the planes, suffering only localized damage. On the basis of a review of smoke plumes and fire spread, for each tower, the engineers concluded that the fires did not lead to the collapses of the floors affected before the towers fell. Additionally, the engineers claim that computer modeling shows that the failure of columns alone, independent of the floors explains the collapses.
...

The Silverstein report also concludes that fire temperatures were lower than typical "fully developed" office fires. The fires were fueled by office furniture and floor contents initially ignited by the jet fuel, which burned out quickly. Dust and debris distributed by the crashes inhibited the fires, which at the impact floors were between 750°F and 1,300°F.



To recap my comments about this from the previous thread:

What Weidlinger got right was that failure of the floor trusses wasn't the cause of the tower collapses. What they got wrong was the idea that, lacking a truss collapse, it made sense to propose that the columns or the core could get hot enough to simultaneously and completely fail. There is not even a preliminary attempt to estimate real temperatures in various parts of the towers, just a blanket assertion that the columns must have failed. The cores are the poorest areas in terms of fuel, and would conduct heat away very quickly from any area of high temperature. Also the oxygen must come from the outside, making the area around the core the poorest prospect for a hot fire (and no, the cores did not act as chimneys).


Having, I think correctly concluded that truss failure was not the initiating event in the twin tower collapses, Levy states the obvious: there must have been a sudden complete and simultaneous failure of all the supporting columns. Since the idea of a controlled demolition is clearly not part of the universe of possibilities that he considers, the only remaining mechanism of column failure he can draw on is weakening by heat. But their own report points out that the fires were not particularly hot.

This gap between proposed collapse mechanism and the real conditions in the towers accounts for Levy's puzzled tone in the interview. But cognitive filters are powerful things, and certain assumptions about the nature of the world can be changed only with great difficulty.



http://www.cooperativeresearch.org/timeline/2001/ireizine072601.html