Quote:
Originally Posted by raymor
Said as only someone who has never bent steel can say it.
At 1350F, austenite forms and the steel becomes pliable.
By 1400, you can easily bend structural steel by hand.
Even at 700° it's a lot softer than it is at room temp.
If you have a propane torch, try it. When your steel turns red that's 1400F. It will bend easily.
There is also confusion about the IGNITION temperature of fuel, the temp at which it lights, versus the COMBUSTION temperature, or the heat of the flame after it lights. The elevator shafts in the buildings' core with a few thousand gallons of jet fuel poured down would make very large blowtorches. Those could reach 3000°, double the temperature need to turn the core support structure to the consistency of taffy.
The design of the supporting core, which held the elevator shafts and was key to structural integrity, caused the buildings to collapse inward. Don't take my word for it though. Go out in your garage with a torch that burns hydrocarbon fuel. Get a piece of steel a little thicker than you can bend with your hands. Get a sour in the middle red hot with that hydrocarbon torch and see how easily you can bend the steel in half. Try it before arguing any more about it.
Don't burn your house down trying it, though. Have a bucket of water handy.
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Good post. That is true except by all accounts no fuel left the very upper floors.
I guess I have to look into further what high carbon building frame steel like the Twin Towers would have. What temp it would melt or sag enough to be weak enough not to suport the INERTIA of the first floors above crashing down say 50 feet at MOST and then pancaking which is what happened.
But since no fuel reached the bottom floors HOW did they sag. I dont believe the lower untouched floor's steel would crumble as it did. It is way stronger than that.
If you seperated a Tower (for sake of argument) at 50 stories and raised the upper 50 stories 100 feet to free fall on the 50 (untouched and structurally sound) stories below, the 50 stories below would NOT crumble or pancake. Would not happen. Maybe the first couple floors only (frames we're talking) would be bent and seriously impacted but the ones under would NOT pancake.
Pancaking is where it ONLY looks like a demolition.
As for the temps, I had heard high carbon building frames can tolerate over 2000 and upwards of 2800 degrees before seriously faulting.