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Title: Profile: National Institute of Standards and Technology (NIST)
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http://www.cooperativeresearch.org/entity.jsp?entity=nationa
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Published: May 19, 2007
Author: Paul Thompson
Post Date: 2007-05-19 07:06:33 by Kamala
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Keywords: 911
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Entity Tags: National Institute of Standards and Technology, World Trade Center
Timeline Tags: Complete 911 Timeline
The jet fuel that spilled from Flight 11 when it hit the North Tower (see 8:46 a.m. September 11, 2001) has mostly burned up by this time. The National Institute of Standards and Technology (NIST), which investigates the collapses, will say “The initial jet fuel fires themselves lasted at most a few minutes.” [National Institute of Standards and Technology, 9/2005, pp. 183
Entity Tags: Forman Williams, World Trade Center, National Institute of Standards and Technology
Timeline Tags: Complete 911 Timeline
Entity Tags: National Institute of Standards and Technology, World Trade Center
Timeline Tags: Complete 911 Timeline
The jet fuel that spilled from Flight 175 when it hit the South Tower (see 9:03 a.m. September 11, 2001) has mostly burned up by this time. The National Institute of Standards and Technology (NIST), which later investigates the collapses, will say the “initial jet fuel fires themselves lasted at most a few minutes.” [National Institute of Standards and Technology, 9/2005, pp. 183
Entity Tags: World Trade Center, National Institute of Standards and Technology, Forman Williams
Timeline Tags: Complete 911 Timeline
The exterior wall on the east side of the World Trade Center’s South Tower apparently bows before the building collapses. The first inquiry into the collapse, by the Federal Emergency Management Agency and the American Society of Civil Engineers, states that the perimeter walls bow outward. “Expansion of floor slabs and framing results in outward deflection of columns and potential overload,” the investigation concludes. [Federal Emergency Management Agency, 5/1/2002, pp. 2-25] However, a subsequent report by the National Institute of Standards and Technology states that the east wall of the South Tower bows inward. In places the wall is said to bow inward by between seven and nine inches at floor 80, and NIST interprets this bowing to mean that the floors must be sagging. NIST will find that the sagging and bowing are two of the seven major factors that led to the collapse of each tower, as the bowing walls are no longer able to support their share of the buildings’ weight, causing the buildings to tilt and the upper sections to fall. [National Institute of Standards and Technology, 9/2005, pp. 43-46, 87
Entity Tags: Federal Emergency Management Agency, World Trade Center, National Institute of Standards and Technology
Timeline Tags: Complete 911 Timeline
The exterior wall on the south side of the World Trade Center’s North Tower apparently bows before the building collapses. The first inquiry into the collapse, by the Federal Emergency Management Agency and the American Society of Civil Engineers, states that the perimeter walls bow outward (see (9:21 a.m.-9:59 a.m. September 11, 2001)). However, a subsequent report by the National Institute of Standards and Technology states that the south wall of the North Tower bows inward. In places the wall is said to bow inward by approximately 55 inches at floor 97, and NIST interprets this bowing to mean that the floors must be sagging. NIST will find that the sagging and bowing are two of the seven major factors that led to the collapse of each tower, as the bowing walls are no longer able to support their share of the buildings’ weight, causing the buildings to tilt and the upper sections to fall. [National Institute of Standards and Technology, 9/2005, pp. 32-34, 87
Entity Tags: World Trade Center, National Institute of Standards and Technology, Federal Emergency Management Agency
Timeline Tags: Complete 911 Timeline
Following the attacks, there is no agreement on the speed with which the Twin Towers of the World Trade Center collapsed on 9/11 (see 9:59 a.m. September 11, 2001 and 10:28 a.m. September 11, 2001). The 9/11 Commission says that the South Tower collapsed in “ten seconds” and the National Institute of Standards and Technology says that tops of the buildings came down “essentially in free fall.” [9/11 Commission, 7/24/2004, pp. 305; National Institute of Standards and Technology, 9/2005, pp. 146
Entity Tags: World Trade Center, Frank Greening, David Ray Griffin, 9/11 Commission, National Institute of Standards and Technology
Timeline Tags: Complete 911 Timeline
Entity Tags: Thomas Eager, World Trade Center, National Institute of Standards and Technology
Timeline Tags: Complete 911 Timeline
Entity Tags: National Institute of Standards and Technology, World Trade Center, Federal Emergency Management Agency
Timeline Tags: Complete 911 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
During the course of its three-year investigation of the World Trade Center collapses, the National Institute of Standards and Technology (NIST) performs computer simulations of the behavior of each WTC tower on 9/11. In its final report, released in October 2005 (see October 26, 2005), it will describe having determined which variables most affected the outcome of its various simulations. Then, “[f]or each of the most influential variables, a central or middle value and reasonable high and low values were identified.” However, “[u]pon a preliminary examination of the middle cases, it became clear that the towers would likely remain standing. The less severe cases were discarded after the aircraft impact results were compared to observed events. The middle cases… were discarded after the structural response analysis of major subsystems were compared to observed events.” Therefore, the “more severe case… was used for the global analysis of each tower.” But, to “the extent that the simulations deviated from the photographic evidence or eyewitness reports, the investigators adjusted the input, but only within the range of physical reality.” [National Institute of Standards and Technology, 9/2005, pp. 143-144
Entity Tags: National Institute of Standards and Technology, World Trade Center
Timeline Tags: Complete 911 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
Entity Tags: National Institute of Standards and Technology, New York Port Authority, World Trade Center
Timeline Tags: Complete 911 Timeline
At the end of a two-day meeting to discuss the progress of their investigation of the WTC collapses on 9/11, National Institute of Standards and Technology (NIST) investigators say that early tests on steel beams recovered from the World Trade Center showed they met or were stronger than design requirements. NIST has collected 236 pieces of steel from the wreckage of the towers. Tests have found that the steel beams exceeded requirements to bear 36,000 pounds per square inch, and were often capable of bearing around 42,000 pounds per square inch. Lead investigator Shyam Sunder says that if further testing corroborates these findings, this will rule out weak steel as a factor in the collapses. [National Institute of Standards and Technology, 8/26/2003; Associated Press, 8/28/2003] The final report of the NIST investigation, released in 2005, will corroborate this finding: “Overall, approximately 87 percent of all perimeter and core column steel tested exceeded the required minimum yield strengths specified in design documents. Test data for the remaining samples were below specifications, but were within the expected variability and did not affect the safety of the towers on September 11, 2001.” It also will point out: “Of the more than 170 areas examined on 16 perimeter column panels, only three columns had evidence that the steel reached temperatures above 250°C.… Only two core column specimens had sufficient paint remaining to make such an analysis, and their temperatures did not reach 250°C.… Using metallographic analysis, NIST determined that there was no evidence that any of the samples had reached temperatures above 600 °C.” [National Institute of Standards and Technology, 9/2005, pp. 89-90
Entity Tags: World Trade Center, National Institute of Standards and Technology
Timeline Tags: Complete 911 Timeline
Entity Tags: Shyam Sunder, National Institute of Standards and Technology, World Trade Center
Timeline Tags: Complete 911 Timeline
Kevin Ryan, the laboratory director at Environmental Health Laboratories Inc., which is a subsidiary of Underwriters Laboratories Inc., writes an e-mail to the National Institute of Standards and Technology (NIST)—the agency currently investigating the WTC collapses—in which he challenges the official theory regarding the WTC collapses. According to Ryan, Underwriters Laboratories Inc. was the company that certified the steel components used in the construction of the World Trade Center, and it had been agreed that the samples it certified met all requirements. His e-mail states, “This story just does not add up. If steel from [the Twin Towers] did soften or melt, I’m sure we can all agree that this was certainly not due to jet fuel fires of any kind, let alone the briefly burning fires in those towers.” His e-mail is published on the Internet, and generates interest on many websites. Days later, Kevin Ryan is fired because, according to a company spokesman, he “expressed his own opinions as though they were institutional opinions and beliefs” of Underwriters Laboratories. According to Underwriters Laboratories, “there is no evidence” that any firm tested the materials used to build the towers. They also say that Ryan was not involved in any way with their fire protection division, which had conducted testing at NIST’s request. [South Bend Tribune, 11/22/2004]
Entity Tags: World Trade Center, National Institute of Standards and Technology, Underwriters Laboratories Inc., Kevin Ryan
Timeline Tags: Complete 911 Timeline
The National Institute of Standards and Technology (NIST), which is conducting an investigation into the WTC collapses on 9/11, releases three new reports. Investigators say that the Twin Towers would probably have remained standing if the fireproofing material that surrounded the buildings’ structural steel had not been stripped away when the planes hit. Their report states that “[t]he jet fuel, which ignited the fires, was mostly consumed within the first few minutes after impact. The fires that burned for almost the entire time that the buildings remained standing were due mainly to burning building contents and, to a lesser extent, aircraft contents, not jet fuel.” However, they claim, without the loss of fireproofing during the planes’ impacts, the heat from the fires would have been insufficient to cause the buildings to collapse. They say that although the architects had in 1964 tested the impact of a Boeing 707 airplane crashing into the 80th floor of one of the towers, they never envisioned the intense fires that ensued. NIST also reports that the time taken by survivors from the North Tower to descend a flight of stairs was about double the slowest evacuation speed estimated in a standard fire engineering text. They state: “approximately 87 percent of the WTC tower occupants, including more than 99 percent below the floors of impact, were able to evacuate successfully.” However, they say, if each tower had been full when they were hit, as many as 14,000 people could have died. [National Institute of Standards and Technology, 4/5/2005; Associated Press, 4/5/2005; New York Times, 4/5/2005; Associated Press, 4/6/2005]
Entity Tags: World Trade Center, National Institute of Standards and Technology
Timeline Tags: Complete 911 Timeline
Based upon its three-year investigation of the WTC collapses, the National Institute of Standards and Technology (NIST) calls for changes in the planning, construction, and operation of skyscrapers. NIST releases 43 draft reports, totaling about 10,000 pages, for public comments. These include 25 pages of recommendations, intended to learn from 9/11 and make building occupants and emergency responders safer in any future disasters. NIST’s inquiry has been conducted by more than 200 technical experts and contractors, and had two main parts: to look at the causes of the collapses and to identify weaknesses in building codes. Their recommendations include specific improvements to building standards, codes and practices; changes to evacuation and emergency response procedures; and research to help prevent future building failures. NIST does not have the authority to change building codes, but hopes to influence the policies of local authorities. The cost of implementing their recommended changes would add an estimated extra 2 to 5 percent to the development costs of buildings. Some are critical of their recommendations. Structural engineer Jon Magnusson, whose firm is the descendant of the company that designed the Twin Towers, says, “They are leading the public down the wrong path. They are saying we are going to fix the codes in order to deal with Sept. 11th. The physics say that you can’t do that.” [New York Times, 6/22/2005; National Institute of Standards and Technology, 6/23/2005; Associated Press, 6/24/2005] The New York Times points out that between 1989 and 1999, only five civilians had been killed in some 6,900 reported high-rise office building fires within the US. [New York Times, 6/24/2005] NIST will release its final report on the Twin Towers collapses four months later (see October 26, 2005).
Entity Tags: National Institute of Standards and Technology, World Trade Center, Jon Magnusson
Timeline Tags: Complete 911 Timeline
Both towers of the World Trade Center tilted to one side before beginning to fall on 9/11 (see 9:59 a.m. September 11, 2001 and 10:28 a.m. September 11, 2001). The National Institute of Standards and Technology, which investigated the collapses (see August 21, 2002), states that the South Tower, which was hit on its south side, tilted about 7-8 degrees to the east and 3-4 degrees to the south, and the North Tower, which was hit on its north side, tilted about 8 degrees to the south, before starting to fall. [National Institute of Standards and Technology, 9/2005, pp. 300, 308
Entity Tags: World Trade Center, Frank Greening, National Institute of Standards and Technology
Timeline Tags: Complete 911 Timeline
The British publication New Civil Engineer reports that, despite calls from leading structural and fire engineers, WTC collapse investigators with the National Institute of Standards and Technology (NIST) are refusing to show computer visualizations of the Twin Towers’ collapses. Despite having shown detailed computer generated visualizations of the plane impacts and the development of fires in the WTC at a recent conference, it showed no visualizations of the actual collapse mechanisms of the towers. Colin Bailey, a professor of structural engineering at the University of Manchester, complains, “NIST should really show the visualisations; otherwise the opportunity to correlate them back to the video evidence and identify any errors in the modelling will be lost.” A leading US structural engineer says that NIST’s “global structural model” is less sophisticated than its plane impact and fire models: “The software used has been pushed to new limits, and there have been a lot of simplifications, extrapolations and judgement calls.” [New Civil Engineer, 10/6/2005]
Entity Tags: World Trade Center, National Institute of Standards and Technology, Colin Bailey
Timeline Tags: Complete 911 Timeline
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
Entity Tags: Glenn Corbett, National Institute of Standards and Technology, World Trade Center
Timeline Tags: Complete 911 Timeline
National Institute of Standards and Technology (NIST) releases a 12-page appendix to its final reports on the WTC collapses (see October 26, 2005) detailing tests it conducted on samples of the type of fireproofing used in the WTC. An earlier NIST report had concluded that loss of fireproofing was a major factor in the collapses (see April 5, 2005). The appendix was not included in earlier drafts of the report (see June 23, 2005) [National Institute of Standards and Technology, 6/23/2005
Entity Tags: World Trade Center, National Institute of Standards and Technology
Timeline Tags: Complete 911 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: National Institute of Standards and Technology, Shyam Sunder
Timeline Tags: Complete 911 Timeline
The National Institute of Standards and Technology (NIST) issues a seven-page fact sheet to counter alternative theories about the WTC collapses. NIST conducted a three-year study of the collapses, and concluded they were caused by the damage when the planes hit combined with the effects of the ensuing fires. However, many people—what the New York Times calls an “angry minority”—believe there was US government complicity in 9/11, and a recent poll (see July 6-24, 2006) found 16 percent of Americans believe the WTC towers were brought down with explosives. [National Institute of Standards and Technology, 8/31/2006; New York Times, 9/2/2006; Reuters, 9/2/2006] The fact sheet responds to 14 “Frequently Asked Questions.” Some of its key points include the following:
Entity Tags: Kevin Ryan, National Institute of Standards and Technology
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Profile: National Institute of Standards and Technology (NIST)
National Institute of Standards and Technology was a participant or observer in the following events:
8:46 a.m. September 11, 2001: Flight 11 Hits the North Tower of the World Trade Center
The hole caused by the Flight 11 crash. [Source: Reuters]Flight 11 slams into the WTC North Tower (Building 1). Seismic records pinpoint the crash at 26 seconds after 8:46 a.m. [CNN, 9/12/2001; New York Times, 9/12/2001; North American Aerospace Defense Command, 9/18/2001; USA Today, 12/20/2001; USA Today, 8/13/2002; Associated Press, 8/19/2002; Newsday, 9/10/2002; New York Times, 9/11/2002] Investigators believe the plane still has about 10,000 gallons of fuel (see 8:57 a.m. September 11, 2001). [New York Times, 9/11/2002] The plane strikes the 93rd through 99th floors in the 110-story building. No one above the crash line survives; approximately 1,360 people die. Below the crash line, approximately 72 die and more than 4,000 survive. Both towers are slightly less than half full at the time of the attack, with between 5,000 to 7,000 people in each tower. This number is lower than expected. Many office workers have not yet shown up to work, and tourists to the observation deck opening at 9:30 A.M. have yet to arrive. [USA Today, 12/20/2001; National Institute of Standards and Technology, 9/2005, pp. 20-22 
] The impact severs some columns on the north side of the North Tower. Each tower is designed as a “tube-in-tube” structure and the steel columns which support its weight are arranged around the perimeter and in the core. The plane, which weighs 283,600 lb and is traveling at an estimated speed of around 430 mph (see October 2002-October 2005), severs 35 of the building’s 236 perimeter columns and damages another two. The damage to the South Tower’s perimeter will be similar (see 9:03 a.m. September 11, 2001). [National Institute of Standards and Technology, 9/2005, pp. 5-9, 20, 22 ] The perimeter columns bear about half of the tower’s weight, so this damage reduces its ability to bear gravity loads by about 7.5 percent. [National Institute of Standards and Technology, 9/2005, pp. 6 ] The actual damage to the 47 core columns is not known, as there are no photographs or videos of it, but there will be much speculation about this after 9/11. It will be suggested that some parts of the aircraft may have damaged the core even after crashing through the exterior wall. According to the National Institute of Standards and Technology (NIST): “Moving at 500 mph, an engine broke any exterior column it hit. If the engine missed the floor slab, the majority of the engine core remained intact and had enough residual momentum to sever a core column upon direct impact.” [National Institute of Standards and Technology, 9/2005, pp. 107 ] According to NIST’s base case computer model, three of the core columns are severed and another ten suffer some damage. [National Institute of Standards & Technology, 9/2005, pp. 189 ] If this is accurate, it means that the impact damage to the core reduces the Tower’s strength by another approximately 7.5 percent, meaning that the building loses about 15 percent of its strength in total. This damage will be cited after 9/11 by NIST and others researchers as an event contributing to the building’s collapse (see October 23, 2002 and October 19, 2004). In addition, some of the fireproofing on the steel columns and trusses may be dislodged. The original fireproofing on the fire floors was mostly Blazeshield DC/F, but some of the fireproofing on the flooring has recently been upgraded to Blazeshield II, which is about 20 percent denser and 20 percent more adhesive. [National Institute of Standards & Technology, 9/2005, pp. xxxvi, 83 ] Photographs and videos of the towers will not show the state of fireproofing inside the buildings, but NIST will estimate the damage to it using a computer model. Its severe case model (see (October 2002-October 2005)) will predict that 43 of the 47 core columns are stripped of their fireproofing on one or more floors and that fireproofing is stripped from trusses covering 60,000 ft2 of floor area, the equivalent of about one and a half floors. NIST will say that the loss of fireproofing is a major cause of the collapse (see April 5, 2005), but only performs 15 tests on fireproofing samples (see October 26, 2005). [National Institute of Standards and Technology, 9/2005, pp. 23 ] According to NIST, more fireproofing is stripped from the South Tower (see 9:03 a.m. September 11, 2001). 8:57 a.m. September 11, 2001: Jet Fuel in North Tower Burns Up
] Engineering professor Forman Williams will say the jet fuel “burned for maybe 10 minutes.” [Popular Mechanics, 3/2005] Flight 11, a Boeing 767, had a fuel capacity of 23,980 gallons, but was only carrying about 10,000 gallons when it hit the WTC. NIST will estimate that less than 1,500 gallons were consumed in a fireball inside the tower and a comparable amount was consumed in the fireballs outside the building. Therefore, approximately 7,000 gallons splashed onto the office furnishings and started fires on various floors. However, after the jet fuel is used up, office fires burn until the building collapses. NIST will calculate that there were about four pounds per square foot of combustibles in the office space, or about 60 tons per floor. Offices in the WTC actually have fewer combustibles than some other similar spaces due to the small number of interior walls and limited bookshelf space. NIST will later find that only three of sixteen perimeter columns it recovers reached a temperature of 250°C and neither of the two core columns it retrieves reached this temperature. NIST will also find that none of the samples it acquires reaches a temperature above 600°C (see August 27, 2003). Although steel does not melt until its temperature is about 1,600°C, it may begin to lose significant strength at over 500°C. [National Institute of Standards and Technology, 9/2005, pp. 20, 29, 24, 77 ] The jet fuel will also burn up in the South Tower about 10 minutes after it is hit (see 9:13 a.m. September 11, 2001). 9:03 a.m. September 11, 2001: Flight 175 Crashes into WTC South Tower; Millions Watch Live on Television
Flight 175 hits the WTC South Tower. The picture was taken from a traffic helicopter. [Source: WABC 7/ Salient Stills]Flight 175 hits the South Tower of the World Trade Center (Tower Two). Seismic records pinpoint the time at six seconds before 9:03 a.m. (rounded to 9:03 a.m.). [New York Times, 9/12/2001; CNN, 9/12/2001; CNN, 9/17/2001; North American Aerospace Defense Command, 9/18/2001; USA Today, 12/20/2001; Associated Press, 8/19/2002; USA Today, 9/2/2002; New York Times, 9/11/2002] Millions watch the crash live on television. The plane strikes the 77th through 85th floors in the 110-story building. Approximately 100 people are killed or injured in the initial impact; 600 people in the tower eventually die. All but four of those killed work above the crash point. The death toll is far lower than in the North Tower because about two-thirds of the South Tower’s occupants have evacuated the building in the 17 minutes since the first tower was struck. [USA Today, 12/20/2001; National Institute of Standards and Technology, 9/2005, pp. 5-9, 41 ] The combined death toll from the two towers is estimated at 2,819, not including the hijackers. [Associated Press, 8/19/2002] The impact severs some columns on the south side of the South Tower. Each of the Twin Towers is designed as a “tube-in-tube” structure and the steel columns which support its weight are arranged around the perimeter and in the core. The plane, which is traveling at an estimated speed of around 500 mph (see October 2002-October 2005), severs 33 of the building’s 236 perimeter columns and damages another one. [National Institute of Standards and Technology, 9/2005, pp. 39 ] The perimeter columns bear about half of the tower’s weight, so the damage to them reduces the tower’s ability to bear gravity loads by about 7.1 percent. [National Institute of Standards and Technology, 9/2005, pp. 6 ] The actual damage to the 47 core columns is not known, as there are no photographs or videos of it, but there will be much speculation about this after 9/11. It will be claimed that some parts of the aircraft may have been able to damage the core even after crashing through the exterior wall (see 8:46 a.m. September 11, 2001). [National Institute of Standards and Technology, 9/2005, pp. 107 ] According to NIST’s base case model, five of the core columns are severed and another five suffer some damage. [National Institute of Standards & Technology, 9/2005, pp. 235 ] This may reduce the tower’s ability to bear loads by a further approximately 8 percent, meaning that the aircraft impact accounted for a loss of about 15 percent of the building’s strength. This damage will be cited as an event contributing to the building’s collapse after 9/11 (see October 23, 2002 and October 19, 2004). NIST’s base case estimate of damage to the North Tower’s core will be similar, even though the aircraft impact there was dissimilar (see 8:46 a.m. September 11, 2001). Flight 11 hit the North Tower’s core head on, whereas Flight 175 only hits the corner of the South Tower’s core. [National Institute of Standards and Technology, 9/2005, pp. 20-23, 38-41 ] In addition, some of the fireproofing on the steel columns and trusses may be dislodged (see 8:46 a.m. September 11, 2001). [National Institute of Standards & Technology, 9/2005, pp. xxxvi, 83 ] Photographs and videos of the towers will not show the state of fireproofing inside the buildings, but the National Institute of Standards and Technology (NIST) will try to estimate the damage to fireproofing using a series of computer models. Its severe case model (see (October 2002-October 2005)) will predict that 39 of the 47 core columns are stripped of their fireproofing on one or more floors and that fireproofing is stripped from trusses covering 80,000 ft2 of floor area, the equivalent of about two floors. NIST will say that the loss of fireproofing is a major cause of the collapse (see April 5, 2005), but only performs 15 tests on fireproofing samples (see October 26, 2005). [National Institute of Standards and Technology, 9/2005, pp. 41 ] According to NIST, less fireproofing is stripped from the North Tower (see 8:46 a.m. September 11, 2001). 9:13 a.m. September 11, 2001: Jet Fuel in South Tower Burns Up
] Engineering professor Forman Williams will say the jet fuel “burned for maybe 10 minutes.” [Popular Mechanics, 3/2005] Flight 175, a Boeing 767, had a capacity of 23,980 gallons, but was only carrying about 9,100 gallons of fuel when it hit the WTC. NIST will estimate that less than 1,500 gallons were consumed in a fireball inside the tower and 910 to 2,275 gallons were consumed in the fireballs outside the building. Approximately 6,100 gallons therefore splashed onto the office furnishings and started fires on various floors. However, after the jet fuel is used up, office fires burn until the building collapses. NIST will calculate that there were about four pounds per square foot of combustibles in the office space, or about 60 tons per floor. Offices in the WTC actually had fewer combustibles than other similar spaces due to the small number of interior walls and limited bookshelf space. NIST will later find that only three of sixteen perimeter columns it recovers reached a temperature of 250°C and neither of the two core columns it retrieves reached this temperature. NIST will also find that none of the samples it acquires reached a temperature above 600°C (see August 27, 2003). While steel does not melt until its temperature is about 1,600°C, it may begin to lose significant strength at over 500°C. [National Institute of Standards and Technology, 9/2005, pp. 29, 38, 42, 77 ] The jet fuel also burned up in the North Tower about 10 minutes after it was hit (see 8:57 a.m. September 11, 2001). When a group of firefighters reach the bottom impact floor in the South Tower just before collapse, they only find two isolated fires (see 9:52 a.m. September 11, 2001). (9:21 a.m.-9:59 a.m. September 11, 2001): Exterior Wall of South Tower May Bow Outwards or Inwards before Collapse
] A wall in the North Tower also apparently bows before the building collapses (see 10:23 a.m. September 11, 2001). 10:23 a.m. September 11, 2001: Exterior Wall of North Tower May Bow Outwards or Inwards before Collapse
] September 12, 2001-September 2005: Duration of WTC Collapse in Dispute
] In the dispute over the reason for the WTC’s collapse after 9/11, it is claimed that, if the towers fell in ten seconds, then this is evidence they were destroyed by explosives. For example, David Ray Griffin, a theologian and outspoken critic of commission’s report, writes, “For a 1,300-foot building, however, ten seconds is almost free-fall speed. But if each floor produced just a little resistance, so that breaking through each one took half a second, the collapse of all those floors—80 or 95 of them—would have taken 40 to 47 seconds. Can we really believe that the upper part of the buildings encountered virtually no resistance from the lower part?” [Griffin, 2004, pp. 16] But according to Canadian scientist Frank Greening, who studies the Twin Towers’ collapse, the freefall time would be about 9.6 seconds, but he calculates that it takes longer for the buildings to fall—twelve to thirteen and a half seconds—and states this does not indicate that explosives were used. [Canadian Broadcasting Corporation, 8/25/2005] September 12, 2001-September 2005: Weight of WTC Towers in Dispute
Ronald Hamburger, a member of NIST’s WTC team and advocate of the ‘piledriver’ theory. [Source: National Council of Structural Engineers' Associations]After 9/11, the scientists investigating the WTC collapse give very different figures for the buildings’ weight. Some sources say that each building weighed 500,000 tons. For example, MIT professor Thomas Eager writes, “The total weight of each tower was about 500,000 t.” [Scientific American, 10/9/2001; Eagar and Musso, 12/2001; Frank Greening, 2/16/2006, pp. 23 ; PBS, 8/2006] However, the National Institute of Standards and Technology (NIST) states that the buildings weighed only 250,000 tons each. [National Institute of Standards and Technology, 9/2005, pp. 32 ] One theory explaining the building’s total collapse is that the upper section acts as a “piledriver” and smashes through the floors below it. [BBC, 9/13/2001; Stanford Report, 12/5/2001] The heavier the upper block above the impact zone, the more likely it is to be able to destroy the other floors as it falls. December 2001: Scientific Journal Describes ‘Eutectic Mixture’ in WTC Steel
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 ] August 21, 2002: Commencement of NIST Investigation Announced
] (October 2002-October 2005): NIST Adjusts Input Data so Computer Simulations of WTC Result in Collapses
] October 2002-October 2005: NIST Tries to Estimate Speed of Aircraft Impacting WTC
] 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 ; National Institute of Standards & Technology, 9/2005, pp. 152-165 ; National Institute of Standards and Technology, 9/2005, pp. 109 ] May 7, 2003: NIST Investigators Issue Progress Report; Say Tests Were Not Conducted Regarding How WTC Would Cope With Major Fire
Insulated trusses in the World Trade Center.
[Source: Gilsanz Murray Steficek]At a press briefing in New York City, the National Institute of Standards and Technology (NIST) releases a 122-page progress report on its investigation into the WTC collapses. NIST began its study in August 2002 (see August 21, 2002). Investigators say they believe that the Port Authority of New York and New Jersey, who built the Twin Towers, failed to carry out vital tests to establish how the buildings would cope with a major fire. They have been unable to find evidence that tests were conducted on the fireproofing material used in the buildings. Their report also states that in 1969, builders directed contractors to coat the WTC floor supports with half an inch of spray-on fireproofing. In 1999, the Port Authority issued guidelines to triple the thickness of the fireproofing, and by 9/11, about 30 floors in the upper areas of the two towers had been upgraded. Almost all the floors in the impact zone of the North Tower had their fireproofing upgraded, while in the South Tower just the 78th floor—the lowest in its impact zone—had been upgraded. As the New York Times states, though, “investigators took great care… to say they were nowhere close to definitively determining how and why the towers collapsed after they were struck by hijacked airliners.” [National Institute of Standards and Technology, 5/2003, pp. 81 ; National Institute of Standards and Technology, 5/7/2003; Guardian, 5/8/2003; New York Times, 5/8/2003] August 27, 2003: NIST Investigators Rule Out Weak Steel as a Factor in Collapses
] October 19, 2004: NIST Releases Latest Findings of WTC Investigation; Presents New Hypotheses as to Why the Twin Towers Collapsed
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] November 11, 2004: Laboratory Director Questions Cause of WTC Collapses
April 5, 2005: NIST Releases Latest Findings; Blames WTC Collapses on Loss of Fireproofing
June 23, 2005: NIST Releases 43 Draft Reports; Recommends Changes to Improve Safety of Tall Buildings
September-November 2005: Questions Raised over NIST’s Claims of Pre-Collapse Tilt of WTC Towers
] However, these findings are criticized by Canadian scientist Frank Greening. After examining photo and video evidence, Greening says that the South Tower tilted by no more than two degrees and the North Tower by no more than three degrees before collapse initiation. Greening also says that the tilt angles NIST gives cannot correspond to the downward movement of the towers’ walls NIST claims before they started to fall, and points out that the tilt angles NIST uses are inconsistent throughout its reports. Though Greening agrees with NIST that the towers were destroyed by the plane impacts and fire damage, he concludes that its computer model is “highly inaccurate and therefore of no value in explaining the demise of the Twin Towers.” [Greening, 11/2005 ] Greening is a leading figure in the post-9/11 dispute over why the WTC collapsed and publishes a series of papers dealing with various aspects of the Twin Towers’ collapse. For example, a CBC documentary uses Greening for analysis of the WTC’s fall. [Canadian Broadcasting Corporation, 8/25/2005] October 6, 2005: NIST Refuses to Show Computer Visualizations of WTC Collapses
October 26, 2005: NIST Releases Final Report on Twin Towers Collapses
] 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 ] 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 ] October 26, 2005: NIST Describes WTC Fireproofing Tests
; National Institute of Standards & Technology, 9/2005, pp. 263-274 ; National Institute of Standards and Technology, 9/2005, pp. 149 ] NIST conducted a series of fifteen tests. In the tests projectiles were fired at fireproofing mounted on 12 inch x 12 inch plates, and steel bars with a one inch diameter. The fireproofing used in the tests was Blazeshield DC/F, one of the two grades of fireproofing used on the impact floors. In thirteen of the tests the projectiles were buckshot, which was fired at the steel samples from a modified shotgun at a distance of 29.5 ft. The other two tests used steel bolts and hexagon nuts, fired with less velocity and at closer range. According to NIST, “The test results support the assumption that, within the debris field created by the aircraft impact into WTC 1 and WTC 2, the SFRM [i.e., fireproofing] used for thermal insulation of structural members was damaged and dislodged.” [National Institute of Standards & Technology, 9/2005, pp. 83, 263-274 ] March 20, 2006: Head of US Investigation in WTC Building 7 Does Not Know Why It Collapsed
August 30, 2006: NIST Counters Allegations of Explosive Demolition of the WTC
Regarding whether NIST considered a controlled demolition hypothesis: “NIST found no corroborating evidence for alternative hypotheses suggesting that the WTC towers were brought down… using explosives… Instead, photographs and videos from several angles clearly show that the collapse initiated at the fire and impact floors and that the collapse progressed from the initiating floors downward until the dust clouds obscured the view.” However, it admits, “NIST did not test for the residue” of explosives in the remaining steel from the towers.
Its explanation for puffs of smoke seen coming from each tower as it collapsed: “[T]he falling mass of the building compressed the air ahead of it—much like the action of a piston—forcing smoke and debris out the windows as the stories below failed sequentially.”
Its explanation for a stream of yellow molten metal that poured down the side of the South Tower shortly before it collapsed (see (9:50 a.m.) September 11, 2001). NIST previously claimed it was aluminum, but this should not have been yellow in color: “Pure liquid aluminum would be expected to appear silvery. However, the molten metal was very likely mixed with large amounts of hot, partially burned, solid organic materials (e.g., furniture, carpets, partitions and computers) which can display an orange glow.”
Regarding reports of molten steel in the wreckage at Ground Zero (see September 12, 2001-February 2002): “Any molten steel in the wreckage was more likely due to the high temperature resulting from long exposure to combustion within the pile than to short exposure to fires or explosions while the buildings were standing.”
Regarding the collapse of WTC 7 (see (5:20 p.m.) September 11, 2001): “While NIST has found no evidence of a blast or controlled demolition event, NIST would like to determine the magnitude of hypothetical blast scenarios that could have led to the structural failure of one or more critical elements.” [National Institute of Standards and Technology, 8/30/2006] In response to the fact sheet, Kevin Ryan, the coeditor of the online Journal of 9/11 Studies, says, “The list of answers NIST has provided is generating more questions, and more skepticism, than ever before.” He says, “NIST is a group of government scientists whose leaders are Bush appointees, and therefore their report is not likely to veer from the political story.” [New York Times, 9/2/2006; Reuters, 9/2/2006]