The Way that the Twin Towers collapsed Didn't Look Right

[Klaralven]

11. The collapse is consistent with their design

Each tower was a 200 x 200 foot tube with 244 strong steel columns around the perimeter forming a strong steel tube. In the center was a strong column housing the elevators and utilities. The floors were reinforced concrete tied to the exterior columns and central tubes.

Horizontal ties between the columns were strong enough so that the vertical load on columns destroyed by the impact were transferred to intact adjacent columns. This prevented the section of the building above the impact from toppling over.

The fuel load of the planes ignited multiple floors. As the fires heated the floor structures, they eventually sheared loose from the central column and the exterior tube. The floors pancaked straight down successively shearing off floors below. The air pressure bulged the tube outward, allowing the section of the building above the impact to also fall straight down into the exterior tube.

So the collapse of the towers has been pretty well analysed and explained. The collapse of Building 7 is less well explained.

See also Why the World Trade Center Towers Fell on 9/11

https://www.thoughtco.com/why-world-trade-center-towers-fell-177706