Quote:
Originally Posted by Alky
FEMA's official report said the jet fuel burned off within minutes.
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That's correct...
However, the burning jet fuel ignited much of the contents on numerous floors. The building contents is what fueled the fire, and over time the heat
weakened the steel.
Steel need
not melt to be substantially weakened, as in lose upwards of 50% of its normal strength, and excessively deflect (bend) under what would otherwise be normal loads. To make matters worse, many of the truss connections themselves were damaged in addition to being weakened from the prolonged heat of the building contents burning.
Many people have the misconception that the WTC 1&2 towers were built of super-special materials / over-engineered construction. The reality is that the steel used was nothing overly special, and the construction was highly economized with minimal use of concrete ... ie. the critical core structure, as a cost saving measure, was only encased in drywall!
Ron