Further to Lawrence's and my discussion of the cause of the collapse of the
World Trade Center, it would seem from the gathering evidence that Lawrence
was correct in saying that it was mainly a matter of the high temperatures.
I was wrong in saying that the floors were welded to the load bearing steel
tubes (in the centre and the perimeter) and that these welds were the cause
of weakness. I now understood that the floors were, in fact, riveted. All
this -- and a great deal more -- may be read in yesterday's issue of The
New Yorker ("The Tower Builder").
I'll take a little credit for originally suggesting that a
three-dimensional frame structure, as in the Empire State Building, might
have stood up to the impact better and not caused progressive collapse of
the open-plan floors -- as also some stress engineers at a recent
conference believe. But Lawrence must take much more credit for very
sensibly pointing out that the extreme temperatures of the fires (2,000�C)
were by far and away the most serious aspect. Almost all engineers are
agreed that no building could be designed to withstand the fire caused by
10,000 gallons of jet fuel.
Keith Hudson
___________________________________________________________________
Keith Hudson, General Editor, Calus <http://www.calus.org>
6 Upper Camden Place, Bath BA1 5HX, England
Tel: +44 1225 312622; Fax: +44 1225 447727;
mailto:[EMAIL PROTECTED]
________________________________________________________________________
