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Context of 'June 18, 2004: NIST Presents ‘Working Hypothesis’ of WTC 7 Collapse'

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FEMA’s World Trade Center Building Performance Study.FEMA’s World Trade Center Building Performance Study. [Source: FEMA]FEMA releases its report of the WTC collapses. It concludes, “[W]ith the information and time available, the sequence of events leading to the collapse of each tower could not be definitively determined.” On Building 7: “The specifics of the fires in WTC 7 and how they caused the building to collapse remain unknown at this time.” [Federal Emergency Management Agency, 5/1/2002]

Entity Tags: World Trade Center, Federal Emergency Management Agency

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

The National Institute of Standards and Technology (NIST)—an agency of the US Commerce Department’s Technology Administration—announces details of its forthcoming investigation into the collapses of the World Trade Center Twin Towers and Building 7 on 9/11. The NIST investigation aims “to investigate the building construction, the materials used, and the technical conditions that contributed to the outcome of the World Trade Center (WTC) disaster.” It also aims to examine the activities of building occupants and emergency responders on 9/11, studying such issues as emergency communications within the WTC, the movement of people during the evacuations, and issues around persons with disabilities. Leading technical experts from industry, academia, and other laboratories, alongside NIST’s own expert staff, will participate in the investigation. Expert professionals from the private sector will also be involved. Glenn Corbett, a fire science professor at John Jay College, says, “This is going to be the most extensive building disaster investigation ever performed.” [Associated Press, 8/21/2002; National Institute of Standards and Technology, 8/21/2002; National Institute of Standards and Technology, 8/3/2005] The investigation is formally authorized in October 2002, when the National Construction Safety Team Act is signed into law. The act, which gives NIST authorization to investigate major building failures in the US, is written largely as a result of the World Trade Center collapses. [National Institute of Standards and Technology, 10/2/2002; New York Times, 5/8/2003] NIST’s investigation is originally proposed to last two years, with a budget of $16 million. [National Institute of Standards and Technology, 8/21/2002] However, it eventually will last three years, with its final report into the collapses of the Twin Towers being released in October 2005 (see October 26, 2005). A previous analysis of the WTC collapses conducted by FEMA and the American Society of Civil Engineers (ASCE) was completed earlier in 2002 (see May 1, 2002), but this had a budget of just $1.1 million. By the time NIST starts its investigation, much of the crucial steel debris from the WTC collapses has already been destroyed (see September 12-October 2001). They later refer to there being a “scarcity of physical evidence that is typically available in place for reconstruction of a disaster.” [National Institute of Standards and Technology, 9/2005, pp. xxxvi]

Entity Tags: World Trade Center, National Institute of Standards and Technology, Glenn Corbett

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

The National Institute of Standards and Technology (NIST) issues a progress report on its investigation into the World Trade Center collapses. Since 2002, NIST has been investigating the collapses of the Twin Towers and WTC Building 7 (see August 21, 2002). The progress report includes its “working hypothesis” for the collapse of WTC 7. This was a 47-story building, located about 350 feet from the north side of WTC 1, which collapsed completely at around 5:20 in the afternoon of 9/11. The report claims that “fire appears to have played a key role” in the collapse, though it points out, “No fire was observed or reported in the afternoon on floors 1-5, 10, or above Floor 13.” It also says, “there may have been some physical damage on the south side of the building.” NIST summarizes its working hypothesis of the WTC 7 collapse as follows:
bullet “An initial local failure at the lower floors (below Floor 13) of the building due to fire and/or debris induced structural damage of a critical column (the initiating event), which supported a large span floor bay with an area of about 2,000 square feet.”
bullet “Vertical progression of the initial local failure up to the east penthouse, as large floor bays were unable to redistribute the loads, bringing down the interior structure below the east penthouse.”
bullet “Horizontal progression of the failure across the lower floors… triggered by damage due to the vertical failure, resulting in the disproportionate collapse of the entire structure.”
NIST claims this hypothesis “is consistent with all evidence currently held by NIST, including photographs and videos, eyewitness accounts and emergency communication records,” but says it “will be revised and updated as results of ongoing, more comprehensive analyses become available.” [National Institute of Standards and Technology, 6/2004, pp. L1, L3, L17, L34, L38, L51-L52 pdf file; National Institute of Standards and Technology, 6/18/2004] NIST will release its final reports on the collapses of the Twin Towers in October 2005 (see October 26, 2005). As of mid-2007, it has yet to release a final report on the collapse of WTC 7. In early 2006, Dr. S. Shyam Sunder, who is the lead investigator for NIST’s WTC investigation, will admit, “truthfully, I don’t really know” what caused WTC 7 to collapse. He will add, “We’ve had trouble getting a handle on building no. 7” (see March 20, 2006). [New York Magazine, 3/20/2006] An earlier report on the WTC collapses, released by the Federal Emergency Management Agency (FEMA) in May 2002, had been inconclusive on what caused WTC 7 to collapse, and stated that “Further research, investigation, and analyses” were necessary (see May 1, 2002). [Federal Emergency Management Agency, 5/1/2002, pp. 5-31]

Entity Tags: World Trade Center, National Institute of Standards and Technology

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

The 43 NIST reports ran to over 10,000 pages.The 43 NIST reports ran to over 10,000 pages. [Source: NIST]The National Institute of Standards and Technology (NIST) issues the final report of its three-year, $16 million study into the WTC collapses on 9/11. NIST has produced over 10,000 pages of findings, and its report includes 30 recommendations for improving building safety, such as having wider stairwells and structurally hardened elevators for use in emergencies. The recommendations are mostly the same as those outlined in an earlier draft of the report (see June 23, 2005). [Engineering News-Record, 10/27/2005; New York Times, 10/27/2005] NIST has made some amendments and clarifications, though, based upon nearly 500 comments received during a six-week public review period. [National Institute of Standards and Technology, 10/26/2005] NIST’s theory about what caused the Twin Towers to collapse remains the same as that described in its previously released findings (see October 19, 2004). However, the NIST’s account only examines events up to the initiation of each collapse; the investigation “does not actually include the structural behavior of the tower after the conditions for collapse initiation were reached and collapse became inevitable.” [National Institute of Standards and Technology, 9/2005, pp. 82] NIST makes no mention of molten metal found at the collapse site in the weeks and months after 9/11, which has been described in numerous reports (see September 12, 2001-February 2002). The “NIST found no corroborating evidence for alternative hypotheses suggesting that the WTC towers were brought down by controlled demolition using explosives planted prior to September 11, 2001.” [National Institute of Standards and Technology, 9/2005, pp. 146] Members of Congress are critical of NIST’s recommendations, saying they are not detailed enough, or adequately documented, to be rapidly incorporated into standard building code publications. [New York Times, 10/27/2005] According to Glenn Corbett, a technical adviser to NIST and fire science professor at John Jay College, NIST is not aggressive enough to carry out major forensic investigations. He says, “Instead of a gumshoe inquiry that left no stone unturned, I believe the investigations were treated more like research projects in which they waited for information to flow to them.” [Associated Press, 10/26/2005; US Congress, 10/26/2005 pdf file] NIST will release its final report on the collapse of Building 7 of the WTC separately, at a later date. [National Institute of Standards and Technology, 9/2005, pp. xiii]

Entity Tags: World Trade Center, Glenn Corbett, National Institute of Standards and Technology

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

Dr. S. Shyam Sunder, head of the National Institute of Standards and Technology government investigation into the collapse of the World Trade Center building, is asked about the collapse of WTC Building 7. Sunder says that he hopes to release something about that by the end of 2006. He adds, NIST did have some “preliminary hypotheses… We are studying the horizontal movement east to west, internal to the structure, on the fifth to seventh floors.… But truthfully, I don’t really know. We’ve had trouble getting a handle on building No. 7.” [New York Magazine, 3/20/2006]

Entity Tags: Shyam Sunder, National Institute of Standards and Technology

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

The National Institute of Standards and Technology (NIST) releases a draft version of the final report of its investigation of the collapse of World Trade Center Building 7, the 47-story skyscraper which collapsed late in the afternoon of 9/11 (see (5:20 p.m.) September 11, 2001). [National Institute of Standards and Technology, 8/21/2008] The report describes NIST’s conclusions on how fires that followed the impact of debris from the north WTC tower’s collapse resulted in the eventual collapse of WTC 7. It evaluates the emergency response and building evacuation procedures, and provides 13 recommendations for construction of buildings in the future, and improved procedures and practices. [National Institute of Standards and Technology, 8/2008, pp. xiii pdf file] Some of the report’s key findings are:
bullet NIST describes its theory of what caused WTC 7 to collapse: “The probable collapse sequence… was initiated by the buckling of a critical interior column.… This column had become unsupported over nine stories after initial local fire-induced damage led to a cascade of local floor failures. The buckling of this column led to a vertical progression of floor failures up to the roof and to the buckling of adjacent interior columns to the south of the critical column. An east-to-west horizontal progression of interior column buckling followed, due to loss of lateral support to adjacent columns, forces exerted by falling debris, and load redistribution from other buckled columns. The exterior columns then buckled as the failed building core moved downward, redistributing its loads to the exterior columns. Global collapse occurred as the entire building above the buckled region moved downward as a single unit.” [National Institute of Standards and Technology, 8/2008, pp. xxxii pdf file]
bullet The collapse of WTC 7 “represents the first known instance of the total collapse of a tall building primarily due to fires. The collapse could not have been prevented without controlling the fires before most of the combustible building contents were consumed.” [National Institute of Standards and Technology, 8/2008, pp. 43 pdf file]
bullet The fires in WTC 7 “were ignited as a result of the impact of debris from the collapse of WTC 1, which was approximately 370 ft to the south.… The fires were ignited on at least 10 floors; however, only the fires on floors 7 through 9 and 11 through 13 grew and lasted until the time of the building collapse.” [National Institute of Standards and Technology, 8/2008, pp. xxxi-xxxii pdf file]
bullet “Even without the initial structural damage caused by debris impact from the collapse of WTC 1, WTC 7 would have collapsed from fires having the same characteristics as those experienced on September 11, 2001.” [National Institute of Standards and Technology, 8/2008, pp. 44 pdf file]
bullet “Had a water supply for the automatic sprinkler system been available and had the sprinkler system operated as designed, it is likely that fires in WTC 7 would have been controlled and the collapse prevented.” [National Institute of Standards and Technology, 8/2008, pp. 43 pdf file]
bullet Other skyscrapers had previously survived comparable fires. “The fires in WTC 7 were similar to those that have occurred previously in several tall buildings (One New York Plaza, 1970, First Interstate Bank, 1988, and One Meridian Plaza, 1991) where the automatic sprinklers did not function or were not present. However, because of differences between their structural designs and that of WTC 7, these three buildings did not collapse.” [National Institute of Standards and Technology, 8/2008, pp. 43 pdf file]
bullet NIST found that “temperatures did not exceed 300°C in the core or perimeter columns in WTC 7,” including the three interior columns that NIST says were the first to buckle in the collapse. “None of these columns were significantly weakened by elevated temperatures.” [National Institute of Standards and Technology, 8/2008, pp. 49-50 pdf file]
bullet NIST says it found “no evidence to suggest that WTC 7 was not designed in a manner generally consistent with applicable building codes and standards.” [National Institute of Standards and Technology, 8/2008, pp. 53 pdf file]
bullet The report concludes that neither explosives nor fuel oil fires fed by diesel tanks in WTC 7 played any role in the collapse (see August 21, 2008 and August 21, 2008). [National Institute of Standards and Technology, 8/2008, pp. 44-45 pdf file]
bullet However, the report points out that WTC 7 “and the records kept within it were destroyed, and the remains of all the WTC buildings were disposed of before congressional action and funding was available for this investigation to begin. As a result, there are some facts that could not be discerned, and thus there are uncertainties in this accounting. Nonetheless, NIST was able to gather sufficient evidence and documentation to conduct a full investigation upon which to reach firm findings and recommendations.” [National Institute of Standards and Technology, 8/2008, pp. xxxi pdf file]
NIST released a progress report in June 2004, which had included its “working hypothesis” at that time for the collapse of WTC 7 (see June 18, 2004). [National Institute of Standards and Technology, 6/18/2004] After suggestions are made by members of the public in response to the current draft report, NIST will release the finished version of the report in November 2008, which includes the same major findings and recommendations as the draft version (see November 20, 2008). [National Institute of Standards and Technology, 11/20/2008]

Entity Tags: World Trade Center, National Institute of Standards and Technology

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

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