So sick of hearing about the comparisons of a steel building collapsing from fire, and also the fact steel melts at a higher temp than jet fuel.
Fact 1 - The buildings had been hit by a jet liner carrying heaps of fuel and travelling at high speed. Approx. 500 knots is the estimated speed. This is a massive force (mass x acceleration) which obviously would have caused major structural damage to the steel columns on the outside shell of the structure as well as support beams for the concrete floors.
The south tower was hit lower down, and hence there was more weight above. Surprise surprise, this tower collapsed much quicker than the north tower.
Everyone references the steel buildings that were burnt out that didn't collapse, however when you look at photos they WERE deformed and also they didn't get struck by fast moving jets full of jet fuel either.
Fact 2 - Jet fuel burns at lower temp than the melting point of steel. 2 things - A) You don't have to melt a metal to make it soft. At 60% of it's melting temp, steel starts to become Plastic and loses strength. B) You can melt steel in a forge using coking coal which burns at lower temp than the melting point of steel. You do this by adding heat energy to the steel from the burbing coke. Add enough heat energy quick enough, and you can melt or even burn steel in a forge.
