The day of or the day after, Freerepublic had someone on this site explaining how it got hot enough inside the building to melt the steel and someone also explained why the pancaking of all that concrete destroyed the lower floors ability to hold the up causing the whole tower to come down both times.
Re: “pancaking”
Stand up.
Not hard, eh? you can stand there all day long.
Now go climb a tree, and from 10+ feet up - jump.
And land, straight vertical, legs fully extended.
Doesn’t go so well, eh?
Imagine a building standing. It can stand there all day long.
Now take out the support verticals for one floor about 3/4 up, about 10+ feet worth.
And expect both the upper and lower floors to stay completely vertical & intact as what was the ceiling impacts what was the floor.
Doesn’t go so well, eh?
The second tower to be hit fell down first, mainly because the first plane hit fairly high up. Your odds of escape from the first building were not too bad unless you were near the top of the building. Second plane hit closer to the middle of the building and that was the building with most of the the jumpers.
The steel didn’t have to melt. Its tensile strength is greatly reduced at high temperature. Its a very well known concept in structural design, and the entire reason structural steel is clad in fire resistant material.
Although it is possible that some of the plastics in the building, combined with the updraft from the fire, and burning jet fuel of course, could have reached the melting point of steel. I never understand where these guys think steel com3s from....do they think there are I Beam forests out there? Of course fire melts steel - its how we shape it and roll it into beams.