How would I know that? Do you know of such a building?
Not that it matters. The time is immaterial. The towers collapsed due to the fires weakening the structural steel. No other explanation is plausible given the facts in evidence.
Not to rational people, that is. People like you will believe any old stupid shit.
Speaking of stupid old shit...If "the towers collapsed due to the fires weakening of the structural steel," then 9/11/2001 is even more historic than even Dick Cheney imagined.
Since never before in recorded history has a single steel-framed skyscraper completely collapsed due to fire, imagine Dick's delight when three skyscrapers fell to the flames on his watch.
Maybe stupid old shits like you and Dick could now tell us how the fires CUT the 47 steel columns running up the center of all towers?
I won't even ask you and Dick for an explanation for the "partly evaporated" steel members in the debris pile or multiple eyewitness accounts of flashes and loud explosions.
Dick might have a heart attack...