to put it schematically, the large organization/big resources theory is consistent with the notion that a decisive counterattack will return things to normal and allow foreign policy continuity. the small organization/modest resources idea makes the possibility of a decisive counterattack less likely, and thus makes foreign policy continuity more uncertain. to put it bluntly, could 'terrorism pay', and eventually result in a change in the US stance towards the Palestinians? re
---------------------------------------------------------------------------- --- Heat of Jet Fuel Fire Likely Caused Collapse of World Trade Buildings By LEE GOMES Staff Reporter of THE WALL STREET JOURNAL
The intense heat of a jet-fuel fire, rather than structural damage from the impact of the airplanes, is probably what led to the collapse of the two World Trade Center buildings.
See full coverage of the attack.
"The mechanical hit takes out a good chunk of the building, but it will still stand," said Larry Anderson, an expert in fire damage at Exponent Failure Analysis Associates, a Menlo Park, Calif., consulting operation. But when you spray thousands of gallons of fuel around, and then light it all at once, that softens the building and leads to its collapse."
Structural engineers who watched television reports of Tuesday's catastrophe noted that the World Trade Center towers remained standing about an hour following the impact of the first plane. During that time, though, a fire was raging out of control on multiple floors of the buildings. Jet fuel is extremely combustible, and produces fires that can easily exceed 2,000 degrees Fahrenheit, more than 500 degrees hotter than other kinds of more routine office fires.
Steel, though, begins to weaken at 800 degrees Fahrenheit, and comes close to melting at around 1,500 degrees. While steel in modern high rises is routinely coated with fire proofing materials, those materials can't protect the steel from prolonged, intense heat.
"Once the physical damage to the building was done, if the fire wasn't extinguished in a very short period of time, the likelihood of collapse was 100%," said Charles Warren, chairman of Engineering Systems Inc., of Aurora, Ill.
Rather than tilting over and falling, the towers appeared to "implode" on top of themselves, in much the same carefully controlled manner as buildings that are demolished.
That is most likely because once the steel at the points of impact could no longer support the floors above them, those floors rushed straight downward, creating an unstoppable force that went all the way to the ground, said Tom O'Donnell, of O'Donnell Consulting Engineers Inc. in Bethel Park, Pa.
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