User:The Devil's Advocate/7 World Trade Center section

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9/11 and collapse
As the North Tower collapsed on September 11, 2001, heavy debris hit 7 World Trade Center damaging the south face of the building and purportedly causing fires inside the building. The collapse also caused damage to the southwest corner with other possible damage including a large vertical gash near the center of the south face. Due to low water pressure there was little or no water to feed sprinklers or manual fire-fighting efforts and fires burned out of control over the course of the day on several floors of the 7 World Trade Center. At approximately 2:00 pm, firefighters noticed a bulge in the southwest corner of 7 World Trade Center between the 10th and 13th floors, which they saw as a sign the building would collapse. Around 3:30 pm 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.

The building started to collapse at 5:20:33 pm EDT, with the crumble of the east mechanical penthouse, and at 5:21:10 pm EDT 7 World Trade Center collapsed completely. While no casualties were associated with the collapse, the debris did cause substantial damage to other buildings including the Fiterman Hall building and the Verizon Building. Fiterman Hall was found not to be salvageable and was demolished in 2009 with plans for reconstruction, while the Verizon Building was able to be restored in 2005.

Files relating to numerous federal investigations had been housed in 7 World Trade Center. The files for thousands of SEC cases were destroyed, though the SEC has said most of the important files were backed up or could be reconstructed. Salomon Brothers, a subsidiary of Citigroup, lost files later requested by the SEC concerning its connection with the WorldCom scandal. The Equal Employment Opportunity Commission estimated over 10,000 of its cases were affected. Investigative files in the Secret Service's largest field office were also lost in the collapse with one Secret Service agent saying, “All the evidence that we stored at 7 World Trade, in all our cases, went down with the building.”



Based on an initial investigation conducted jointly with the Structural Engineering Institute of the American Society of Civil Engineers under leadership of Dr. W. Gene Corley, P.E., the Federal Emergency Management Agency (FEMA) made preliminary findings in May 2002 that the collapse was primarily caused by uncontrolled fires on multiple stories ignited by debris from the Twin Towers and not by damage from the collapse of the towers. It did not reach a final conclusion on the collapse and called for further investigation. Subsequently, the National Institute of Standards and Technology (NIST) was authorized to lead an investigation into the structural failure and collapse of the World Trade Center Twin Towers and 7 World Trade Center. The investigation, led by Dr S. Shyam Sunder, drew upon in-house technical expertise as well as the knowledge of several outside private institutions.

While NIST's investigation of the collapse of the Twin Towers delayed its work on the 7 World Trade Center, NIST still released preliminary reports and updates on the investigation until it released its final report in November 2008. Computer simulations were used in the investigation to model events leading up to collapse initiation and the global response to these events. It was determined that fires fueled by office contents, along with the lack of water to fight them, were responsible for the collapse with no other factors, including diesel fuel from the generators, playing an important role. According to the report, the fires caused floor beams near Column 79 to expand and push a key girder off its seat, triggering nine floors to fail around the column. With this loss of lateral support, Column 79 buckled pulling nearby columns down with it. The collapse then progressed east-to-west across the core, overloading the perimeter support, and caused the entire building above to fall downward as a single unit. The NIST report found no evidence supporting conspiracy theories claiming that 7 World Trade Center was brought down by a controlled demolition.

Based on its investigation, NIST reiterated several recommendations it had made in its earlier report on the collapse of the Twin Towers, and urged immediate action on a further recommendation: that fire resistance should be evaluated under the assumption that sprinklers are unavailable; and that the effects of thermal expansion on floor support systems be considered. Recognizing that current building codes are drawn to prevent loss of life rather than building collapse, the main point of NIST's recommendations was that buildings should not collapse from fire even if sprinklers are unavailable.