You know, I will just make one post on this subject.
I sat there on 11 September 2001 in my house in Charlton, and I watched two planes crash into the WTC towers. Both of them - I saw them - slammed into the buildings and disappeared. Ejecta was thrown out the other three sides of both towers. It was perfectly obvious that the cores of both buildings had been sliced.
That the cores of both buildings were structurally compromised to a fatal extent was confirmed by the testimonies of people who escaped below the crash sites and by the pre-mortem testimonies of the people trapped above the crash sites and by the fire-fighters that were sent in to find a way up.
I have some bitter experience of tearing down reinforced concrete marine structures. I have even more experience of fire damage in steel structures (ships and platforms) and in steel/concrete portal-frame buildings. I was talking by 'phone with a number of people - who will probably come on here to attest to the discussions if people doubt me - on that morning about what we regarded as the inevitable fact that both buildings were going to come down before the morning was finished.