The reason steel frame buildings don't collapse is because you have to get to about 2,200 degrees F for steel to melt. Jet fuel burns at around 500 degrees F. However, if you had a perfect air fuel mixture and put the tip of the flame directly under the steel you might be able to get it to 1500 degrees F which in turn might cause steel to soften up enough, under the weight and deform and give way.
Here is the problem, we saw black smoke coming out of the tower, that means the fire was starved for oxygen, so it didn't get to 1500 degrees. Second, the building collapsed straight down which means every single support had to collapse at the same time. No one would expect that, we would expect the tower to bow in like a can being crushed, tip over and fall.
Third problem, we could have easily confirmed this if the investigators had been able to see the steel, but the military put it under lock and key and guarded it, preventing the investigators from seeing it and then shipped it off to China to be melted down destroying evidence.
Fourth problem, the US has a fantastic facility that can replicate a fire in a 3 story building. They could have replicated the fire from the airplane to see if it would have caused the steel to be deformed. We use this facility all the time to determine exactly what happened in a fire. However, they never tested their theory of the jet fuel causing the steel to break. That is the biggest insult to the 3,000 people who died, their death was even worth doing a real investigation.
Fifth problem, the fire at the world Trade center continued for 99 days. It is the longest fire in history. I was in NYC, the Fire Department was hosing the fire down for 3 months before it finally went out. They measured the temperature and it was well over 3,000 degrees, closer to 4,000 degrees F. That is not paper, that is not jet fuel, that is thermite.