At 15:09 29/09/01 -0400, you wrote: >Steel melts at between 1200 and 1600 degrees. The fire caused by the planes >with their full fuel loads is calculated to have reached 2000 degrees. The >structural steel melted. Nothing shoddy about the design or construction. > >Lawrence
Yes, I'm well aware of this. But the Towers did not collapse due to fire. That would have accounted for the yielding of only one floor of the buildings. The progressive collapse of the rest was due to inherent structural weakness. The Empire State Building also sustained the full impact of an airplane fifty-odd years ago. It was a smaller plane with a smaller fuel tank, but the building was properly designed and constructed. The impact devasted one floor only. Keith > > >> -----Original Message----- >> From: [EMAIL PROTECTED] >> [mailto:[EMAIL PROTECTED]]On Behalf Of Keith Hudson >> Sent: Saturday, September 29, 2001 6:27 PM >> To: [EMAIL PROTECTED] >> Subject: Examination question about the World Trade Center Towers) >> >> >> Now I don't know much about the construction of skyscrapers. In my main >> business we confine ourselves to designing houses and nothing taller. The >> only really crucial thing to know is the necessary thickness of >> load-bearing joists across spans of various widths. But what goes almost >> without saying is that joists have to be set into strong >> load-bearing walls. >> >> >> Examination question: >> Will there be an enquiry into the design of the two Towers? In particular, >> why were the walls and corners constructed out of thin plate >> steel and thin >> box girders so that each floor couldn't support the collapsed >> weight of the >> ones above. >> >> >> P.S. On the BBC Web page a (apparently fully qualified, fully legal!) >> British architect has been opining that the Towers collapsed because they >> were too large and thus the gravitational energy was >> overwhelmingly massive >> once consecutive floor collapses started. This is nonsense. I've seen >> stress calculations showing that, theoretically, skyscrapers >> could be built >> (using existing materials) up to two miles high without any compressive >> collapse due to gravity. No, I think that the World Trade Center Towers >> were incredibly badly designed and (probably) shoddily built with bad >> welding, etc. I wonder how many other modern skyscrapers in New York, >> London, etc are designed in similar ways and I wonder how many of >> them will >> continue to be occupied in the coming weeks once investigators >> start asking >> questions such as the one I've proposed above. >> >> And another thing while I am at it. In very tall buildings where it takes >> occupants well over an hour to walk down the stairs in emergencies (as >> occurred in the Towers), there needs to be another mode of exit. An >> inertial variant of fireman's pole (on a ratchet or absailing principle) >> could easily be designed for escape within a few minutes on any floor >> (*and* without people trampling over one another, *and* which blind and >> handicapped people could also safely use). >> >> 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] >> ________________________________________________________________________ > > > > ___________________________________________________________________ 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] ________________________________________________________________________
