yeah, 47-story skyscrapers often fall into their own basement in 6.2 seconds, from 2 small pockets of fire.
You might want to take a metallurgical class so you have a better understanding of how heat effects steel, particularly structural steel.
Or just ask an engineer like myself.
Steel has a crystalline structure which can be easily manipulated with heat.
I could hand you a piece of steel (for instance 303 grade that you can easily cut or machine)
OTOH, I could hand you a piece of steel so that has been heat-treated to Rockwell scale 85 and it would be so hard you couldn't even scratch it.
Hardened steel when exposed to extreme temperatures changes the internal properties of the steel.
No, the steel in the towers did not melt, that would be impossible.
What did happen was that the heat generated from the explosion changed the hardness of the steel, basically
changing it's fundamental properties and making it weak as shit, and unable to support *EVEN ITS OWN WEIGHT*. So how can one possibly expect it to hold the millions of tons on top of it?
Granted, the public will never know all the details of 911 but I'm sure there is no grandiose conspiracy either.