There's way, WAAY too much steel for such a weakening to even start being a remote possibility.
There's not NEARLY enough heat in those fires, and way too much ongoing dissipation.
Steel framed buildings stood after burning much hotter and much longer, plenty of times.
You arm-wave but provide no quantitative rationale. Plenty of heat in a closed-box fireplace burning 50 tons of kerosene. Enough to heat the structural steel to 30% or less of its room-temperature strength. All you need to do is reduce the strength margins to zero for a catastrophic collapse. No ordinary building would have so much high-energy-density fuel to combust. There is some basis for thinking that some of the aircraft aluminum contributed to the combustion.
This meme is stupid and works against your credibility. Does steel have to melt to get weak? At what temperature does steel degrade below spec?
You have a LOT of homework to do, especially in physics.
That would have to include you. If steel loses 80% of its strength, all the structural margins are gone and collapse is the inevitable result.
There's way, WAAY too much steel for such a weakening to even start being a remote possibility. There's not NEARLY enough heat in those fires, and way too much ongoing dissipation.
Steel framed buildings stood after burning much hotter and much longer, plenty of times.
You arm-wave but provide no quantitative rationale. Plenty of heat in a closed-box fireplace burning 50 tons of kerosene. Enough to heat the structural steel to 30% or less of its room-temperature strength. All you need to do is reduce the strength margins to zero for a catastrophic collapse. No ordinary building would have so much high-energy-density fuel to combust. There is some basis for thinking that some of the aircraft aluminum contributed to the combustion.