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Context of 'September 12, 2001: FEMA Assembles Team to Analyze WTC Collapses, but Investigation Is Severely Hampered'

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Damage to the southwest corner of WTC 7.Damage to the southwest corner of WTC 7. [Source: Arquelio Galarza]World Trade Center Building 7 (WTC 7) suffers some damage, caused by debris from the collapse of the north WTC tower, according to later official reports. [Federal Emergency Management Agency, 5/1/2002, pp. 5-16; National Institute of Standards and Technology, 11/2008, pp. 16]
WTC 7 Undamaged by South Tower Collapse - WTC 7 is a 47-story office building located 370 feet north of the North Tower (WTC 1). In the final report of its investigation into WTC 7’s collapse, published in November 2008 (see November 20, 2008), the National Institute of Standards and Technology (NIST) will state that although a few windows on the lower floors of WTC 7’s south face were broken when the South Tower (WTC 2) collapsed at 9:59 a.m. (see 9:59 a.m. September 11, 2001), “None of the large pieces of debris from WTC 2 hit WTC 7, because of the large distance between the two buildings,” and there is “no evidence of structural damage to WTC 7” as a result of the South Tower’s collapse.
Debris Reportedly Damages Exterior Columns - However, when the North Tower collapses (see 10:28 a.m. September 11, 2001), some fragments of debris are “forcibly ejected” from it, and travel “distances up to hundreds of meters.” According to NIST, pieces of this debris “hit WTC 7, severing six columns on floors 7 through 17 on the south face and one column on the west face near the southwest corner.” NIST will add that the debris also causes “structural damage between floor 44 and the roof,” and breaks a large number of windows on WTC 7’s south face.
Building Core Undamaged - However, NIST will state, based on “photographic evidence, witness accounts, and engineering judgment, it is likely that the structural damage (steel and floor slabs) did not penetrate beyond the perimeter of the building core. At the southwest corner, the structural damage extended only about one-third of the distance from the exterior wall to the building core.” NIST will comment, “Compared to the airplane impact damage to the WTC towers, there was relatively little damage to the interior of WTC 7.” There is also “no superficial or structural damage” to WTC 7’s north and east faces. And the sprayed fire resistive material that has been applied to the building’s steel columns, girders, and beams is only damaged in the “immediate vicinity of the WTC 1 debris impact.” NIST will admit, however, that there are “uncertainties” in its accounting of the events leading up to the collapse of WTC 7, because “the remains of all the WTC buildings were disposed of before Congressional action and funding was available for [its] investigation [of the WTC collapses] to begin” (see Shortly After September 11, 2001 and September 12-October 2001). [National Institute of Standards and Technology, 8/21/2008; National Institute of Standards and Technology, 11/2008, pp. 15-16]
FEMA Describes WTC 7 Damage - According to an earlier report on the collapse of WTC 7, published by the Federal Emergency Management Agency (FEMA) in May 2002 (see May 1, 2002), at that time, the “extent and severity of the resulting damage to WTC 7” when the North Tower collapses “are currently unknown.” But based on “photographic evidence and eyewitness accounts,” it is “assumed that the south side of the building was damaged to some degree.” FEMA’s report will state: “It does not appear that the collapse of WTC 1 affected the roof, or the east, west, and north elevations of WTC 7 in any significant way. However, there was damage to the southwest corner of WTC 7 at approximately floors 8 to 20, 24, 25, and 39 to 46.” The report will add: “According to firefighters’ eyewitness accounts from outside of the building, approximately floors 8-18 were damaged to some degree. Other eyewitness accounts relate that there was additional damage to the south elevation.” [Federal Emergency Management Agency, 5/1/2002, pp. 5-16, 5-20]
Structural Damage Not Responsible for Collapse - WTC 7 will collapse at 5:20 p.m. this afternoon (see (5:20 p.m.) September 11, 2001). [National Institute of Standards and Technology, 8/21/2008] However, NIST will conclude that the structural damage the building suffers plays no role in causing it to come down. NIST will state, “Other than initiating the fires in WTC 7, the damage from the debris from WTC 1 had little effect on initiating the collapse of WTC 7.” [National Institute of Standards and Technology, 11/2008, pp. xxxvii] WTC 7 suffers fires on some floors, which are reportedly initiated by debris from the collapse of the North Tower (see (10:28 a.m.-5:20 p.m.) September 11, 2001). According to NIST, it is these fires, “rather than the structural damage that resulted from the impacts” of debris, which “initiated the building’s collapse.” [National Institute of Standards and Technology, 8/21/2008]

Entity Tags: World Trade Center, National Institute of Standards and Technology, Federal Emergency Management Agency

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

W. Gene Corley.W. Gene Corley. [Source: ASCE]The Federal Emergency Management Agency (FEMA) and its contractor, Greenhorne and O’Mara, Inc., from Greenbelt, Maryland, begin putting together a Building Performance Assessment Team (BPAT), to conduct a formal analysis of the World Trade Center collapses, and produce a report of its findings. FEMA routinely deploys such teams following disasters, like floods or hurricanes. The 23-member BPAT team set up at the WTC collapse site is assembled by the American Society of Civil Engineers (ASCE), and headed by Dr. W. Gene Corley of Construction Technologies Laboratories in Skokie, Illinois. Corley was previously the principal investigator for FEMA’s study of the Murrah Building, in Oklahoma City in 1995. [New Yorker, 11/12/2001] BPAT team members are based nationwide and have to communicate with each other mostly by phone, as they continue with their regular jobs. While some of them are being paid for their efforts, others are working on the investigation voluntarily. They are told not to speak with reporters, under threat of dismissal from the team, supposedly because of the delicacy of the subject with which they are dealing. The BPAT team receives $600,000 of funding from FEMA, plus approximately $500,000 in ASCE in-kind contributions. [New York Times, 12/25/2001; Associated Press, 1/14/2002; US Congress, 3/6/2002] The team will have great difficulty accessing the collapse site and evidence they want to see (see March 6, 2002). They will be unable to get FEMA to obtain such basic data as detailed blueprints of the WTC buildings. FEMA will also refuse to allow them to make appeals to the public for photos and videos of the towers that might aid their investigation. Bureaucratic restrictions will often prevent them from making forensic inspections at Ground Zero, interviewing witnesses, or getting important evidence, like recorded distress calls from people who were trapped in the towers. [Glanz and Lipton, 2004, pp. 330] The end product of their investigation is the FEMA World Trade Center Building Performance Study, released in May 2002 (see May 1, 2002).

Entity Tags: World Trade Center, W. Gene Corley, American Society of Civil Engineers, Federal Emergency Management Agency, Greenhorne and O’Mara, Inc.

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

The American Society of Civil Engineers (ASCE) studies the crash of Flight 77 into the Pentagon and the building’s architectural response to the impact, blast, and subsequent fires. [American Society of Civil Engineers, 1/17/2003] The six-member Pentagon Building Performance Study team is headed by Lead Technical Director Paul F. Mlakar, and also includes Mete A. Sozen. Mlakar and Sozen had previously worked together on the Federal Emergency Management Agency (FEMA) investigation into the Oklahoma City bombing under W. Gene Corley, who is now assigned as FEMA/ASCE’s team leader for the World Trade Center investigation (see September 12, 2001). [Corley et al., 10/1997; Mlakar et al., 1/2003, pp. i pdf file] Some aspects of the Oklahoma City investigation were controversial. [Guardian, 5/5/2001] Sozen is also tasked with “project conception” for Purdue University’s computer simulation of the Pentagon attack, images from which are also used in the Performance Report, when it is issued later (see January 23, 2003). [Purdue University Department of Computer Science, 9/11/2002] The Building Performance Study team only inspects the Pentagon on two occasions. Team leader Mlakar is granted “limited access” to the site for a week from September 14-21, and on October 4, “controlled access” is granted to the full team, which meets with Corley and inspects the site “for approximately four hours.” All airplane debris has been removed by this time, as well as most of the loose debris from the impact and collapse. Along with interviews and technical information provided by the Pentagon Renovation Project, the photos and data gleaned on these visits are the basis of the team’s analysis of the building’s response to the impact of Flight 77. The study is completed in April 2002, though the report will not be released for another nine months. [Mlakar et al., 1/2003, pp. 1, 18 pdf file]

Entity Tags: American Society of Civil Engineers, Mete Sozen, Paul Mlakar, Purdue University, W. Gene Corley, Pentagon

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

Thermal hot spots detected by satellite on September 16, 2001. Red and orange indicate the hottest locations. The World Trade Center Twin Towers footprint is in the lower center and the center of World Trade Center Building 7 is in the upper right.
Thermal hot spots detected by satellite on September 16, 2001. Red and orange indicate the hottest locations. The World Trade Center Twin Towers footprint is in the lower center and the center of World Trade Center Building 7 is in the upper right. [Source: USGS]In response to requests from the Environmental Protection Agency, through the US Geological Survey, NASA flies a plane over the site of the WTC complex, equipped with a remote sensing instrument called AVIRIS. AVIRIS is able to remotely record the near-infrared signature of heat. Analysis of the data it collects indicates temperatures at Ground Zero of above 800 degrees Fahrenheit, with some areas above 1,300 degrees. On September 16, dozens of “hot spots” are seen, but by September 23, only four or five remain. [US Geological Survey, 11/27/2001; US Geological Survey, 10/2002 pdf file] Robert Shaler, the scientist who leads the forensic examination by the New York City medical examiner’s office to identify 9/11 victims, later will state that the “DNA in the bodies” of WTC victims “was in pretty bad shape. These bones were exposed to extreme temperatures.” [US News and World Report, 12/5/2005] Don Carson, a hazardous materials expert, later will say, “There are pieces of steel being pulled out [of the WTC rubble] that are still cherry red. It’s like the charcoal that you put in your grill.… You light it and it stays hot.” [New York Daily News, 11/1/2001] And Dr. Jonathan Barnett, a member of FEMA’s WTC investigation team, will describe steel members in the debris pile that appear to have been partly evaporated in extremely high temperatures. [New York Times, 11/29/2001] Despite the WTC rubble being pumped with an almost constant jet of water, eventually totaling thousands of gallons, almost 12 weeks after 9/11 at least one fire is still burning, making it the longest-burning structural fire in history. [New Scientist, 12/3/2001; CBS News, 12/19/2001] As well as the hot spots, numerous witnesses describe molten metal being found at Ground Zero (see September 12, 2001-February 2002).

Entity Tags: Robert Shaler, Jonathan Barnett, National Aeronautics and Space Administration, Don Carson

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

Dr. Abolhassan Astaneh-Asl examines steel from the World Trade Center.Dr. Abolhassan Astaneh-Asl examines steel from the World Trade Center. [Source: University of California, Berkeley]An engineer investigating the remains of the World Trade Center sees melted girders and other evidence that the towers experienced extreme temperatures on 9/11. Dr. Abolhassan Astaneh-Asl is a professor of civil and environmental engineering at the University of California, Berkeley. He specializes in studying structural damage done by earthquakes and terrorist bombings. [Chronicle of Higher Education, 12/7/2001; CBS News, 3/11/2002] He arrives in New York on September 19 to conduct a two-week scientific reconnaissance of the collapsed towers, hoping to gain an understanding of how they had come down. His project is one of eight financed by the National Science Foundation to study the WTC disaster. [New York Times, 10/2/2001; Berkeleyan, 10/3/2001; US Congress. House. Committee on Science, 3/6/2002] He examines numerous pieces of steel taken from Ground Zero. [Chronicle of Higher Education, 12/7/2001] Astaneh-Asl will describe the WTC as “the best-designed building I have ever seen.” [San Francisco Chronicle, 10/22/2001] Yet he notices unusual warping and other damage in its remaining steel:
bullet At a recycling center in New Jersey, he sees 10-ton steel beams from the towers that look “like giant sticks of twisted licorice.” [Chronicle of Higher Education, 12/7/2001] He shows the San Francisco Chronicle a “banana-shaped, rust-colored piece of steel” that has “twisted like toffee during the terrorist attack.” [San Francisco Chronicle, 10/22/2001]
bullet He later recalls, “I saw melting of girders in [the] World Trade Center.” [PBS, 5/10/2007]
bullet He notes that steel has bent at several connection points that had joined the floors of the WTC to the vertical columns. He describes the connections as being smoothly warped, saying, “If you remember the Salvador Dali paintings with the clocks that are kind of melted—it’s kind of like that.” He adds, “That could only happen if you get steel yellow hot or white hot—perhaps around 2,000 degrees.” [Chronicle of Higher Education, 12/7/2001]
bullet Astaneh-Asl says that steel flanges have been reduced “from an inch thick to paper thin.” [Berkeleyan, 10/3/2001]
bullet He finds a foot-long twisted shard of steel that is “like a piece of bread, but it was high-strength steel.” He comments, “I haven’t seen anything like this [before].” [Berkeley Daily Planet, 10/20/2001]
bullet He finds “severely scorched [steel] members from 40 or so floors below the points of impact [by the planes].” He believes this is the result of the planes having destroyed the elevator walls, thereby allowing burning jet fuel to pour down into the building, igniting fires hundreds of feet below the impact floors. [CBS News, 3/12/2002]
bullet He says that, in some places, the fireproofing used to protect the WTC steel has “melted into a glassy residue.” [New York Times, 10/2/2001]
bullet Astaneh-Asl sees a charred I-beam from WTC Building 7, which collapsed late in the afternoon of 9/11. “The beam, so named because its cross-section looks like a capital I, had clearly endured searing temperatures. Parts of the flat top of the I, once five-eighths of an inch thick, had vaporized.” [New York Times, 10/2/2001]
Other individuals will report seeing molten metal in the remains of the World Trade Center in the weeks and months after 9/11 (see September 12, 2001-February 2002), and data collected by NASA reveals dozens of “hot spots” (some over 1,300 degrees Fahrenheit) at Ground Zero (see September 16-23, 2001). But Thomas Eagar—an engineering professor at the Massachusetts Institute of Technology—later comments that the “temperature of the fire at the WTC [on 9/11] was not unusual, and it was most definitely not capable of melting steel.” [Eagar and Musso, 12/2001] Yet Astaneh-Asl will later put forward the “tentative” conclusion, “The collapse of the [Twin Towers] was most likely due to the intense fire initiated by the jet fuel of the planes and continued due to burning of the building contents.” [Astaneh-Asl, 11/30/2003 pdf file] Astaneh-Asl is a member of the team assembled by the American Society of Civil Engineers to investigate the World Trade Center site after 9/11 (see September 12, 2001), though he will resign from this because he disagrees with its decision to keep findings secret until the initial inquiry has been completed. [New York Times, 10/2/2001; Associated Press, 9/6/2002]

Entity Tags: World Trade Center, Thomas Eagar, Abolhassan Astaneh-Asl

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

A sample of WTC steel eroded and corroded due to eutectic formations.A sample of WTC steel eroded and corroded due to eutectic formations. [Source: FEMA]The Journal of the Minerals, Metals and Materials Society (JOM) reports that the examination of a beam from the remains of WTC Building 7—which collapsed late in the afternoon of 9/11 (see (5:20 p.m.) September 11, 2001)—has revealed “unexpected erosion” of the steel. The article states: “The formation of the eutectic mixture of iron oxide and iron sulfide lowers the temperature at which liquid can form in this steel. This strongly suggests that the temperatures in this region of the steel beam approached around 1,000°C, forming the eutectic liquid by a process similar to making a ‘blacksmith’s weld’ in a hand forge.” [Barnett, Biederman, and Sisson, 12/2001] The New York Times will call this “perhaps the deepest mystery uncovered in the investigation.” [New York Times, 2/2/2002] FEMA’s World Trade Center Building Performance Study, released in May 2002 (see May 1, 2002), will add that the same “unusual erosion patterns” have been observed in a sample of the remaining structural steel from one of the Twin Towers. It will state, “This sulfur-rich liquid penetrated preferentially down grain boundaries of the steel, severely weakening the beam and making it susceptible to erosion.” FEMA is unable to explain this phenomenon, saying, “The severe corrosion and subsequent erosion… are a very unusual event. No clear explanation for the source of the sulfur has been identified.… It is possible that this is the result of long-term heating in the ground following the collapse of the buildings. It is also possible that the phenomenon started prior to collapse and accelerated the weakening of the steel structure.” [Federal Emergency Management Agency, 5/1/2002, pp. C-1 - C-13] Despite FEMA’s call for further research, the National Institute of Standards and Technology (NIST) will make no mention of the eutectic formations in its final report into the WTC collapses, released in late 2005, following its three-year investigation. [National Institute of Standards and Technology, 9/2005, pp. 13]

Entity Tags: National Institute of Standards and Technology, World Trade Center, Federal Emergency Management Agency

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

The House Committee on Science holds a hearing on the investigation into the collapse of the World Trade Center on 9/11. Witnesses from industry, academia, and government testify on the collapses and the subsequent efforts to find out how and why they occurred. The hearings charter points out several problems that have severely hampered investigations. It says, “Early confusion over who was in charge of the [WTC collapse] site and the lack of authority of investigators to impound pieces of steel for examination before they were recycled led to the loss of important pieces of evidence that were destroyed early during the search and rescue effort.… Some of the critical pieces of steel—including the suspension trusses from the top of the towers and the internal support columns—were gone before the first BPAT [Building Performance Assessment Team] team member ever reached the site” (see September 12-October 2001). Furthermore, “The building owners, designers and insurers, prevented independent researchers from gaining access—and delayed the BPAT team in gaining access—to pertinent building documents largely because of liability concerns.” Regarding the decision to rapidly recycle the WTC steel, US Representative Joseph Crowley (D-NY) says, “I do believe that conspiracy theorists are going to have a field day with this,” and says this loss of important physical evidence “is not only unfortunate, it is borderline criminal.” In his statement before the committee, Glenn Corbett, a science professor at John Jay College, claims that the “lack of significant amounts of steel for examination will make it difficult, if not impossible, to make a definitive statement as to the cause and chronology of the collapse.” He also complains, “[W]e are staffing the BPAT with part-time engineers and scientists on a shoestring budget.” [US Congress, 3/6/2002; Associated Press, 3/7/2002]

Entity Tags: World Trade Center, Glenn Corbett, House Committee on Science, Joseph Crowley

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

A structural engineer who was a member of the team assembled by the American Society of Civil Engineers to investigate the World Trade Center site after 9/11 complains about the decision to rapidly destroy the remaining structural steel from the collapsed WTC buildings. Dr. Abolhassan Astaneh-Asl is a professor of civil and environmental engineering at the University of California at Berkeley, and specializes in studying structural damage done by earthquakes and terrorist bombings. [Chronicle of Higher Education, 12/7/2001; CBS News, 3/11/2002; Associated Press, 9/6/2002] He had come to New York a week after 9/11 to examine the collapsed towers, hoping to gain an understanding of how they had come down (see September 19-October 2001). [New York Times, 10/2/2001; US Congress. House. Committee on Science, 3/6/2002] However, New York City officials had decided early on to quickly transport the remaining structural steel to scrap yards, to be shipped abroad and melted down for reuse (see Shortly After September 11, 2001). As CBS News now reports, “As a result, Astaneh has almost certainly missed seeing crucial pieces before they were cut up and sent overseas.” Astaneh-Asl complains: “When there is a car accident and two people are killed, you keep the car until the trial is over. If a plane crashes, not only do you keep the plane, but you assemble all the pieces, take it to a hangar, and put it together. That’s only for 200, 300 people, when they die. In this case you had 3,000 people dead.” He says: “My wish was that we had spent whatever it takes, maybe $50 million, $100 million, and maybe two years, get all this steel, carry it to a lot. Instead of recycling it, put it horizontally, and assemble it. You have maybe 200 engineers, not just myself running around trying to figure out what’s going on. After all, this is a crime scene and you have to figure out exactly what happened for this crime, and learn from it.” However, he adds, “My wish is not what happens.” [CBS News, 3/12/2002] Astaneh-Asl previously told the New York Times that the scrap steel from the WTC was “worth only a few million dollars, a tiny fraction of the billions of dollars the cleanup will cost.” Yet the knowledge that could be gained from it “could save lives in a future disaster.” [New York Times, 10/2/2001]

Entity Tags: World Trade Center, Abolhassan Astaneh-Asl

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

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

One of the key variables in the computer simulations used by the National Institute of Standards and Technology (NIST) (see (October 2002-October 2005)) to explain the WTC collapses is the speed of the aircraft that hit the towers. However, there is no consensus on how fast the planes were traveling. The first estimate was contained in an initial research paper by engineers Zdenek Bazant and Yong Zhou, who stated that the planes were traveling at 342 miles per hour. [Bazant and Zhou, 1/2002 pdf file] However, the Federal Emergency Management Agency (FEMA) and American Society of Civil Engineers (ASCE) report said that the plane that hit the North Tower was traveling at 470 miles per hour, whereas the plane that hit the South Tower was traveling at 590 miles per hour (see May 1, 2002). [Federal Emergency Management Agency, 5/1/2002, pp. 31] NIST initially estimates speeds of 435 miles per hour for the plane that hit the North Tower and 497 miles per hour for the plane that hit the South Tower. These estimates closely match figures produced by the Massachusetts Institute of Technology, which finds speeds of 429 miles per hour and 503 miles per hour for the two planes. However, NIST is dissatisfied with these results and does a second study, which finds speeds of 466 and 545 miles per hour. It then uses speeds of 472 and 570 miles per hour in its severe case model, on which its final report is based. In this model, the simulation of the planes traveling faster means greater damage to the towers’ structure, making them more unstable. [Kausel, 5/2002 pdf file; National Institute of Standards & Technology, 9/2005, pp. 152-165 pdf file; National Institute of Standards and Technology, 9/2005, pp. 109]

Entity Tags: Zdenek Bazant, National Institute of Standards and Technology, World Trade Center, Yong Zhou, Massachusetts Institute of Technology, American Society of Civil Engineers, Federal Emergency Management Agency

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

Matthys Levy.Matthys Levy. [Source: PBS]A report is made publicly available, which the Engineering News-Record calls the “most comprehensive study yet on the destruction of the World Trade Center.” The study was commissioned by WTC leaseholder Silverstein Properties Inc. to support a $7 billion insurance claim, and conducted by a team of engineers from several leading firms, including Weidlinger Associates, LZA Technology/Thornton-Tomasetti, and ARUPFire. It is intended to build on a previous study sponsored by FEMA (see May 1, 2002). The report’s findings are based on an analysis of original structural drawings, thousands of photos, and dozens of videos. Investigators used fire evaluation techniques and powerful computer software to simulate the condition of each tower at critical times between the planes’ impacts and the towers’ collapses. The earlier FEMA investigators had no access to such computer modeling. Matthys Levy, the chairman of Weidlinger Associates and one of the engineers on the study team, says, “The buildings had tremendous reserve capacity and that was reflected in all of the elements we analyzed. In fact, because there were so much excess capacity, the columns even in the impact floors did not buckle immediately, but failed as the result of the fire.” The report states that failure of the WTC’s steel floor supports (“trusses”) did not contribute to the collapses. Instead, the collapses were caused by the failure of steel structural columns that were either destroyed when the planes hit or lost fireproofing, leaving them vulnerable to the weakening effects of the ensuing fires. It says that debris and dust distributed by the plane crashes inhibited the fires, such that the average air temperatures on the impact floors were between 400 and 700°C (750-1,300°F): significantly lower than those associated with typical “fully developed” office fires. However, says Matthys Levy, “By the time the temperature inside the buildings reached 400 degrees, the steel would have lost approximately 50% of its strength. Eventually, gravity took over and the towers began to fall.” Then, according to the analysis led by researchers from LZA Technology/Thornton-Tomasetti, “Once collapse initiated in each tower, essentially all of the interior structure of the tower fell straight down with floors pancaking on top of one another. The network of perimeter steel columns and spandrels acted like a chute to funnel the interior contents into the tower footprint.” According to the computer simulations, the damage to the South Tower’s steel core columns was so severe that the tower should have collapsed immediately after the plane hit. Civil engineer John Osteraas says this incorrect result casts doubt upon some of the study’s predictions. The report concludes that the collapse of the South Tower did not cause or contribute to the subsequent collapse of the North Tower, thus supporting Silverstein Properties’ claim that the terrorist attack represented two occurrences, entitling it to two $3.5 billion insurance policy limits. A separate study commissioned by the insurers contradicts this (see October 23, 2002). The Silverstein report apparently does not examine the collapse of WTC Building 7, a 47-story skyscraper that also collapsed on 9/11 (see (5:20 p.m.) September 11, 2001). It has been passed on to the National Institute of Standards and Technology (NIST), which is undertaking its own investigation of the WTC collapses (see August 21, 2002). [New York Times, 9/30/2002; Business Insurance, 10/23/2002; Silverstein Properties, Inc., 10/23/2002 pdf file; Engineering News-Record, 10/25/2002; New York Times, 10/29/2002; Engineering News-Record, 11/4/2002; Real Estate Weekly, 4/30/2003]

Entity Tags: World Trade Center, Silverstein Properties, Thornton-Tomasetti Engineers, Weidlinger Associates, Matthys Levy

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

Sixteen months after the attack occurred, the American Society of Civil Engineers (ASCE) releases its Pentagon Building Performance Report on the Pentagon’s architectural response to the impact, blast, and subsequent fires caused by the Flight 77 crash on 9/11. [American Society of Civil Engineers, 1/17/2003] The report, which was finished several months earlier (see September 14, 2001-April 2002), admits “the volume of information concerning the aircraft crash… is rather limited,” but the team is able to give some details of the impact. The report reproduces the five frames of security camera footage made public in 2002 that showed the strike on the Pentagon (see March 7, 2002), seeing in them the approaching aircraft with its top about 20 feet above ground before exploding against and into the building. [Mlakar et al., 1/2003, pp. 14 pdf file] The report notes the plane struck a construction generator and vent structure on the lawn and speculates “portions of the wings might have been separated from the fuselage before the aircraft struck the building.” [Mlakar et al., 1/2003, pp. 35-36 pdf file] The ASCE finds that the plane hit the northern edge of Wedge One of the building—its southwest corner—which had been recently renovated, and that the plane made a 90 foot hole in the outer wall, destroying most ground floor support columns there and the limestone and brick fa├žade between and in front of them. Aircraft debris is then reported to have passed through the building’s three outer rings E, D, and C, following the plane’s trajectory, entering the unrenovated Wedge Two towards the end of the path of destruction. [Mlakar et al., 1/2003, pp. 39 pdf file] The report does not say what caused the much-debated hole in the wall of Ring C, which led on to an internal driveway in the middle of the building. However, in a section on the damage caused by the debris it notes, “There was a hole in the east wall of Ring C, emerging into AE drive,” and a photo of the C Ring hole is included in the report. [Mlakar et al., 1/2003, pp. 28 pdf file]

Entity Tags: American Society of Civil Engineers, Pentagon

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

Shyam Sunder.Shyam Sunder. [Source: NIST]The National Institute of Standards and Technology (NIST) releases nearly 500 pages of documents, detailing the latest findings of its investigation of the WTC collapses on 9/11. These include its hypotheses for the collapse sequences of each of the Twin Towers; details of their analysis of interviews with nearly 1,200 building occupants, emergency responders, and victims’ relatives; and information from their analysis of the emergency response and evacuation procedures. Their investigation into the collapses is based upon an analysis of thousands of photos and videos, examination of many of the elements used to construct the towers, and computer-enhanced modeling of the plane impacts and the spreading of the fires. Their hypothesis is that the towers collapsed ultimately due to the fires they suffered: As the fires burned, the buildings’ steel core columns buckled and shortened. This shifted more load to the buildings’ perimeter columns, which were already affected by the heat of the fires, and caused them to give way under the increased stress. Investigators have conducted a test with a reconstructed section of the WTC floor, and found that the original fireproofing was sufficient to meet the New York City building code. They say that had a typical office fire occurred in the towers, without the structural damage and the loss of some fireproofing caused by the plane impacts, it is likely the buildings would have remained standing. Lead investigator Dr. Shyam Sunder says, “The buildings performed as they should have in the airplane impact and extreme fires to which they were subjected. There is nothing there that stands out as abnormal.” NIST’s theories of why the WTC buildings collapsed conflict with an earlier investigation by FEMA, which claimed the collapse of the North Tower had begun in its core, rather than its perimeter columns (see May 1, 2002). [National Institute of Standards and Technology, 10/19/2004; New York Times, 10/20/2004]

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

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

The National Institute of Standards and Technology (NIST) publicly rejects the theory that diesel fuel tanks installed in World Trade Center Building 7 played any role in the 47-story tower’s collapse, late in the afternoon of 9/11. This is clearly set out in a question-and-answer factsheet published on this day, together with an announcement of NIST’s draft report on the building’s collapse (see August 21, 2008 and August 21, 2008). The factsheet asks, “Did fuel oil systems in WTC 7 contribute to its collapse?” The answer is “No…. The worst-case scenarios associated with fires… could not have been sustained long enough, could not have generated sufficient heat to weaken critical interior columns, and/or would have produced large amounts of visible smoke from the lower floors, which were not observed.” [National Institute of Standards and Technology, 8/21/2008; New York Times, 8/21/2008] These findings are echoed in the draft version of its final report on the collapse. [National Institute of Standards and Technology, 8/2008, pp. xxxii pdf file] WTC 7 had three emergency power systems, all of which ran on diesel fuel. The systems contained two 12,000 gallon fuel tanks and two 6,000 gallon tanks located beneath the building’s loading docks, and another 6,000 gallon tank on its first floor. There were also 275 gallon tanks on the fifth, seventh, and eighth floors, and a 50 gallon tank on the ninth floor. [National Institute of Standards and Technology, 8/21/2008] It has previously been suggested that diesel stored in these tanks might have contributed to fires that led to WTC 7’s collapse (see March 2, 2002). [New York Times, 3/2/2002] This possibility was proposed in the final report of the Federal Emergency Management Agency (FEMA) investigation of the WTC collapses, published in May 2002 (see May 1, 2002). [Federal Emergency Management Agency, 5/1/2002, pp. 5-28 - 5-29] But in his summary of the findings of NIST’s three-year study of WTC 7, lead investigator Shyam Sunder says the building’s collapse was “not due to fires from the substantial amount of diesel fuel stored in the building.” [National Institute of Standards and Technology, 8/21/2008]

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

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

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