Posted by Bob A on June 03, 2003 at 12:38:04:
In Reply to: Re: twin towers collapse posted by JF on June 01, 2003 at 20:23:14:
The center core design of WTC 1 and 2 was the main reason they collapsed into the bath tub instead of falling over. WTC 7 did not collapse in the same manor. The heat generated over 7 hours thinned structural members as well as contaminating / diffusing sulfer (supplied by the insulation) into structural steel. WTC 1 and 2 collapsed from changing the natural frequency of the center support core. The fracture was sudden and complete, indicating brittle fracture had occured. With the loss of support in the center of the building the outsides collapsed toward the center.
Please remember this is my opinion and is presented to stimulate debate. I believe WTC 1 and 2 performed beyond for what they were designed for, and even with the horrible loss of 3000 lives, the engineering and architecture saved countless lives
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