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Old 5th December 2007, 04:42 PM   #89
Critical Thinker
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Join Date: Jul 2007
Posts: 405
Originally Posted by Apollo20 View Post

The Cardington Tests are not a meaningful comparison to the WTC fires since they involved a fuel load of 44 kg/m^2. NIST states quite clearly that the WTC fires were fed by 20 kg/m^2 fuel loads. The time vs. temperature profiles in the Cardington Tests were nothing like the equivalent profiles reported by NIST for the workstation fire tests. Also the section factors of the structural members exposed to the WTC fires were generally quite different to the section factors of the steel exposed in the Cardington Tests.

Let's compare apples with apples please.
It would seem the actual fuel load is somewhat controversial, but even accepting the NIST estimate, I doubt that the thermal inertia of something like a floor truss will really make a huge difference, even considering the discrepancy in fuel loadings from cardington to the NIST estimate. In fact a floor beam in cardington will likely have greater thermal inertia than in the case of a WTC floor truss. This will probably only have a marked effect on the columns, which were ultimately lesss important to the collapse than the trusses.

Anyhow, the point is that Kevin Ryan stating that the steel will not exceed 250C is not good enough, a much more detailed analysis is needed than that, such as a time temperature curve for the steel element, or a heat-flux vs time curve, if he does not accept what NIST has produced.

Last edited by cmcaulif; 5th December 2007 at 04:47 PM.
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