That's not correct.they survived for something like half an hour---
WTC1 was hit at 8:46am and collapsed at 10:28am. It stood for about 1 hour and 45 minutes.
WTC2 was hit at 9:03am and collapsed at 9:59am. It stood for about 45 minutes before collapsing.
Not sure where you got "half an hour".
The point being that they DID survive impact of the jets.
What does your post above have to do with the question I asked Rigby5 to explain what was meant by "And the collapsing floors do NOT add more weight,"?the FIRES never went out-----more and more HIGH ENERGY materials reached FLASH POINT and added
to the ongoing INTENSIVE HEAT producing combustion