9/11 Attacks: How Did the World Trade Center Towers Collapse? – Franceinfo

The Twin Towers of the World Trade Center in New York were built in the early 1970s. They were the tallest towers in the world and were the pride of New Yorkers. Their Japanese architect had designed a revolutionary structure: a sort of huge square tube supported by a central core. Thus, 40% of the weight of the towers was carried by their facade made up of 236 steel columns. The rest rested on a central nucleus.

The facades and the core were therefore welded by the floors of the 110 floors. On September 11, 2001, two planes hit the two towers at full speed. On the south tower, the second to be hit, the impact at 900 km / h devastated eight floors, 33 exterior columns, including 10 of the severed central core. The other load-bearing elements are overloaded, but the tower is resisting. It’s the fires that change everything, the fire spreads to the upper floors. The heat becomes so intense that it weakens and deforms the steel beams.