@Charred - I can’t speak to the science behind the steel collapses in the terrorist attacks. I do know that metal fabricators use a variety of metal forming techniques to shape the steel into a particular shape.
From what I understand some of these methods use cold as part of the process while others use heat. I don’t know how much heat is applied using the heat techniques, but I assume that during this process they have an acceptable threshold for how much heat the metal can endure.
Again, whether the steel can withstand more than that or whether the fires of September 11,2001 were much hotter than that threshold, I cannot stay. But the metal fabricators do run their tests through a variety of what-if scenarios as I understand it.