A lot of the jet fuel went up in the initial fireball. Some more went down the elevator shafts and exploded in the lobby. Which is probably what the firefighters heard. There was an elevator that went the full length of the building.....to the restaurant at the top. These "explosions" didn't bring down the building. The building stood after that.

The fire got hot enough to weaken the steel. Because most of the sprayed fire resistive materials would have stripped from the steel when the planes tore through the building. They changed the SFRM requirements in the building codes after that.

Det charges leave a ton of evidence. Miles and miles of det cord would be required and you can make a charge cut through steel AND be quiet. They are linked.

My problem with thermite is, it would leave a ton of evidence. It's effects are very distinctive looking and it would leave blobs of iron and Aluminium oxide everywher

The Structural Engineering group in NY examined the steel. They went to the places in Staten Island where the debris was taken and looked at the steel. The results of thermite would have been noticed