Yes, I might have thought it not possible for two planes to bring down the two towers until I saw it on live TV with my own eyes.

"Until I read a book......." indicates you now believe it. Pretty sad. You need to read some more by real engineers without an agenda. There's a lot more valid engineering that says your belief is nonsense. You need to read that WITH AN OPEN MIND.

Beyond that simple logic can prevail here if you're capable of recognizing it.

WOW... Someone light YOUR flame this morning? A bit of a fixation on this?

heh heh heh...

Indeed. I'm going to guess that BobF does not understand the iron-iron carbide phase diagram.

http://www.sv.vt.edu/classes/MSE2094_NoteBook/96ClassProj/examples/kimcon.html

Steel is one of the most complicated structural materials available. It behaves in vastly different ways depending on carbon concentration and temperature.

The whole reason structural steel is fire protected in buildings isn't because the steel will "melt", it's because elevated temperatures change the microstructure of the steel permanently. Even if the building stays standing, the physical properties of the steel have changed.

Actually BobF lit the fire and then a local instigator fanned the flames.

Huh... I haven't see Ray around this morning...

Yes, I remember an argument that in a fire a steel beam will fail quicker than a wood beam that will burn for quite a while before it weakens enough that it will no longer support it's intended load.

Ray's a novice compared to the master.

Doesn't deserve a comment was my reaction when I heard it before. But the temp differentials are hard to explain away. NIST said none of the steel beams lost even 1% of their strength. Even if they did from the fire well above them, would they all fail uniformly? Would they be blown horizontally in neat sections?

I did a fair amount of online research into this before posting. I saw both sides of the argument expressd.