NIST releases report on WTC 7 collapse

photonic writes: After a 3 years of study, NIST finally released its report on the collapse of World Trade Center building 7. The main conclusion is that the building came down due to fire, not due to debris damage or some conspiracy demolition team. The fire started pretty small after the collapse of WTC 1, but was left to burn several floors out completely. The important finding is that the collapse was triggered by thermal expansion of beams, which could detach asymmetrically loaded girders from the main columns. Some limited pancaking of floors than caused lack of lateral support and buckling of a single column. This triggered the failure of the entire core of the building, which finally fell down as a single piece. Crackpot theories can be discussed in the Digg comments, so please limit the discussion to the science here. All documents can be found here, which read like a porn magazine for finite element junkies. Awesome movies are here. And yes, they used Beowulf clusters to do the simulations, some of which lasted for several months.