How many fires (in world history) have successfully caused skyscrapers to collapse?

Question

http://ap.google.com/article/ALeqM5isReaHAE4U2HLBEPKqetS6J8_BvgD92MOGSO0

Answer 1

Everybody continues on the fire issue. The real issue is the impact energy. considering that a .30/06 will produce in excess of 2800 foot/pounds of energy, just imagine what an x*x weight airliner doing over 300 miles per hour would create. Those building were designed to withstand the force of High winds, Not high Impact.

You folks out there in Conspiracy land will swallow a Camel, yet strain at a gnat.

Answer 2

About the same number as have been collapsed by airplanes hitting them. And that is the same number as have collapsed from any cause. I hope that answers your question.

Answer 3

skyscrapers are fairly new in the history of the whole world.

the two your thinking of, yeah those were crashed in to by big planes.