Since when does a skyscraper collapse from fire?
A hot enough fire weakens metal. Jet fuel, diesel or heating oil burn very hot. If there is enough fuel to burn for an extended period of time things happen.
What caused the twin towers to collapse? It wasn't the direct hit from the airplanes or the weight of the airplanes on the structure. Without the extended fire from the jet fuel the buildings wouldn't have collapsed.
to explain building 7 collapse from fire, you're using the only other example of a skyscraper collapsing (apparently) from fire: the twin towers. lol. of course those were also demolished on purpose, maybe using some sort of nanothermite.
I don't know of any case (other than 9/11) where a steel-framed building collapsed from fire. You?
The buildings that collapsed experienced very unique and unusual circumstances.
Indeed. Man-made ones specifically prepared to bring them down.