Ask Lemmy

It's still a very strange looking collapse. But the sort of damage caused to it by two giant skyscrapers collapsing next to and into it must have subjected it to stresses is was never designed to take.

And a raging fire inside the building near it's base that was left to burn mostly unchecked because most of the firefighters were already killed or their equipment destroyed by towers 1 and 2.

Controlled demolitions target the very weakest parts of a structure, causing a cascading failure throughout the structure. In a huge uncontrolled fire and impact, the same weakest points are by definition the most likely to fail first, so the collapse looks similar. Also WTC7 was built above an existing building, so it's vertical columns didn't go straight down into bedrock, they went down to near street level, and then transferred the load horizontally around the existing building. From the outside it looked like a regular rectangle, but on the inside, it effectively had a giant unsupported hole on the inside. Under normal conditions, structurally sufficient, but if you shake the ever loving fuck out of it twice and then light it on fire with no firefighters nearby...