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Politics : Moderate Forum -- Ignore unavailable to you. Want to Upgrade?

To: GUSTAVE JAEGER who wrote (15030)	1/3/2005 12:01:46 PM
From: zonder	Read Replies (2) \| Respond to of 20773

Gustave - I don't intend to be mean when I say this, but you need to look up the basic facts on such stuff before forming such strong opinions. The sheer mass of the WTC towers --which precludes their complete and utter collapse in a matter of seconds using conventional explosives Hm. Of course you must know by now that they did not collapse "within a matter of seconds" (but lasted for quite a while after planes struck and fires started) and the stuff "used" was not "conventional explosives" (but rather jet fuel). Besides, yes, even mammoth buildings can be collapsed with something as conventional as dynamite attached to structurally important points, as I am sure you must have seen before, the way large buildings are demolished. Unfortunately, even outside of "conventional explosives", large structures can and do collapse under the same unfavorable conditions as smaller structures. I have actually studied this stuff in university, with courses in structure & strength, where, for some unhappy semesters, I was expected to calculate thicknesses of materials and structural members to be used to withstand certain weights etc. So please read the following with the idea that I might actually know what I am talking about here. Steel structures are inherently weak against high-intensity fire, unless their steel parts are encased in cement. Steel that is heated long enough in a fire that is intense enough, quickly loses its load-bearing strength and bends. That is unfortunately quite impossible to do properly in highrise buildings (like the twin towers in question) because the weight of the necessary cement becomes astronomical. Steel structures are designed with the amount and thickness of steel that will, in case of intense fire, permit the building to stand for an amount of time that will permit its occupants to escape. I don't recall the textbook requirement but it is something like a half hour. Then it will go down, because structural steel loses its strength after a certain temperature. This temperature is not necessarily reached (at least widely enough across the structure to make it bend in places and collapse) in most fires. In the case of WTC centers on 9/11, there were two reasons why it was: (1) The two planes were full of jet fuel, enough to take them to the other side of the US. The resulting fire was much hotter and burnt for much longer than it would have, if it had come out of a cigarette butt dropped into a waste basket. (2) WTC towers had core shafts (for utilities like lifts, pipes, etc), which not only carried the heat across the structure but also fed it with oxygen. Thus, it was highly probable from the moment those planes struck WTC that the towers would collapse, except if the fire were immediately put out by some miracle. Which is why, imho, the imbeciles who ordered employees to stay at their desks and work while the buildings they were in were fuming at the top should be publicly flogged.