"As the North Tower collapsed on September 11, 2001, debris hit 7 World Trade Center, damaging the south face of the building and igniting fires. The bottom portion of the building's south face was heavily damaged from debris, including: damage to the southwest corner from the 8th to 18th floor, a large vertical gash on the center-bottom extending at least ten floors, and other damage as high as the 18th floor
A massive fire burned into the afternoon on the 11th and 12th floors of 7 World Trade Center, the flames visible on the east side of the building. During the afternoon, fire was also seen on floors 6–10, 13–14, 19–22, and 29–30. At approximately 2:00 p.m., firefighters noticed a bulge in the southwest corner of 7 World Trade Center between the 10 and 13th floors which was a sign that the building was unstable and might collapse. During the afternoon, firefighters also heard creaking sounds coming from the building. Around 3:30 pm, given that 7 World Trade Center was unstable and would possibly collapse, FDNY Chief Daniel Nigro decided to halt rescue operations, surface removal and searches along the surface of the debris near 7 World Trade Center and evacuate the area due to concerns for the safety of personnel. At 5:20 p.m. EDT on September 11, 2001, 7 World Trade Center collapsed.
Specifically, NIST's interim report on 7 World Trade Center displays photographs of the southwest façade of the building that show it to have significant damage. The report also highlights a 10-story gash in the center of the south façade, toward the bottom, extending approximately a quarter of the way into the interior. A unique aspect of the design of 7 World Trade Center was that each outer structural column was responsible for supporting 2,000 sq ft (186 m²) of floor space, suggesting that the simultaneous removal of a number of columns severely compromised the structure's integrity. Consistent with this theory, news footage shows cracking and bowing of the building's east wall immediately before the collapse, which began at the penthouse floors. In video of the collapse, taken from the north by CBS News and other news media, the first visible sign of collapse is movement in the east penthouse 8.2 seconds before the north wall began to collapse, which took at least another 7 seconds
A progress report was released in June 2004, outlining NIST's working hypothesis. The hypothesis, which was reiterated in a June 2007 status update, is that an initial failure in a critical column occurred below the 13th floor, caused by damage from fire and/or debris induced structural damage of a critical column, from the collapse of the two main towers. The collapse progressed vertically up to the east mechanical penthouse. The interior structure was unable to handle the redistributed load, resulting in horizontal progression of the failure across lower floors, particularly the 5th to 7th floors."
), the progression is as if it were on a plane at 45 degrees to the ground (you just can't do this) and finally the squibs go all the way to the roof, what's the point?
The building didn't have bits standing for a bit afterwards like the towers did but the collapse was not simultaneous, find the vid clip on youtube and look at it.
