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Politics : Bush-The Mastermind behind 9/11? -- Ignore unavailable to you. Want to Upgrade?

To: Don Earl who wrote (618)	5/11/2003 5:43:27 PM
From: Raymond Duray	Read Replies (1) \| Respond to of 20039

Hi Don, Generally I'm in agreement with what you've stated here, one quibble would be regarding this statement: Re: but I think it's pretty hard to explain why a structure where each floor is designed to support the weight of all the floors above, provided almost no resistance whatsoever to the rate of collapse. Les Robertson, the design engineer for the WTC structures, is one of the most successful big building designers in the world. Clearly, he designed the WTC towers to withstand static and live loads throughout the structures. That said, he was hired because he's a practical man and the owners of the building used the type of design that was implemented because it was the most economical plan they could come up with. This meant that the WTC towers were built to newer building standards than were used, for example, in the Empire State Building. If I remember the facts, by using rational design principles and superior tensile strength steel in the columns, Robertson was able to cut the weight of the steel almost in half to what had been used in the Empire State Building, a truly stout structure. So with the design at the bare minimums allowed by the standards of the late 1960's, when Robertson did his calculations, he created a structure that may or may not have been able to withstand the sort of hammer blow that the collapse of the 20 or so upper stories coming down as a unit would generate. I have not read the official engineering report on the collapse. I've seen extensive coverage of this costly document on PBS's The News Hour and read briefly about it from news reports when it was released. I believe that the report tends to find that the dynamic nature of the load imposed as the upper stories collapsed was enough to cause a catastrophic failure lower in the building. Seems plausible enough to me. Though that doesn't answer the anomalies which I'd briefly characterize as 1) seismic activity apparently in anticipation of the collapse of the upper stories 2) pools of molten metal as described by Mark Loizeaux et al 3) the rush to remove structural materials to foreign smelters, excepting several samples selected to be maintained for forensic examination.