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Thread: NIST Final WTC7 Report News Archives

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    NIST Final WTC7 Report News Archives

    8:15 a.m. - Report Due on 9/11 Building Collapse

    http://arkansasmatters.com/content/f...ws/?cid=102561

    Reported by: RNS
    Thursday, Aug 21, 2008 @08:15am CST

    A report will be presented Thursday by the U.S. Commerce Department's National Institute of Standards and Technology regarding the collapse of World Trade Center Building 7 during the terror attacks of September 11, 2001.

    The report on its findings and recommendations from its building and fire safety probe will be unveiled in Gaithersburg, Maryland.

    WTC-7 was a 47-story building that collapsed nearly seven hours after the World Trade Center towers went down.

    The report will identify the probable collapse sequence for the building and will recommend ways that building and fire safety in similar structures can be enhanced.

    The original building was replaced with the new 7 World Trade Center which opened in 2006.

    It's 52 stories tall and its design emphasizes safety, with a reinforced concrete core and thicker fireproofing of steel columns.
    No One Knows Everything. Only Together May We Find The Truth JG


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    Fed gov't finds fires took down building next to twin towers

    http://www.examiner.com/a-1548037~Fe...in_towers.html

    By DEVLIN BARRETT, AP
    8/21/2008

    GAITHERSBURG, Md. (Map, News) - Government investigators have issued a report refuting conspiracy theories that a skyscraper next to the twin towers was brought down by explosives. The report says that fires destroyed World Trade Center 7 on Sept. 11.

    Scientists with the National Institute of Standards and Technology say their three-year investigation of the collapse of the 47-story building was the first known instance of fire causing the total failure of a skyscraper.

    The investigators also conclude that the collapse of the nearby twin towers broke the city water main, leaving the sprinkler system in WTC 7 without water.

    The collapse of building 7 has long been the subject of conspiracy theories that something else brought down the tower.
    No One Knows Everything. Only Together May We Find The Truth JG


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    NIST WTC 7 Investigation Finds Building Fires Caused Collapse

    Report and Recommendations for Improving Building Safety Released for Comment

    http://www.nist.gov/public_affairs/r...wtc082108.html

    8/21/2008

    GAITHERSBURG, Md.—The fall of the 47-story World Trade Center building 7 (WTC 7) in New York City late in the afternoon of Sept. 11, 2001, was primarily due to fires, the Commerce Department’s National Institute of Standards and Technology (NIST) announced today following an extensive, three-year scientific and technical building and fire safety investigation. This was the first known instance of fire causing the total collapse of a tall building, the agency stated as it released for public comment its WTC investigation report and 13 recommendations for improving building and fire safety.

    “Our study found that the fires in WTC 7, which were uncontrolled but otherwise similar to fires experienced in other tall buildings, caused an extraordinary event,” said NIST WTC Lead Investigator Shyam Sunder. “Heating of floor beams and girders caused a critical support column to fail, initiating a fire-induced progressive collapse that brought the building down.”

    “Video and photographic evidence combined with detailed computer simulations show that neither explosives nor fuel oil fires played a role in the collapse of WTC 7,” Sunder said. The NIST investigation team also determined that other elements of the building’s construction—namely trusses, girders and cantilever overhangs that were used to transfer loads from the building superstructure to the columns of the electric substation (over which WTC 7 was constructed) and foundation below—did not play a significant role in the collapse.

    According to the report, a key factor leading to the eventual collapse of WTC 7 was thermal expansion of long-span floor systems at temperatures “hundreds of degrees below those typically considered in current practice for fire resistance ratings." WTC 7 used a structural system design in widespread use.

    Citing its one new recommendation (the other 12 are reiterated from the previously completed investigation of the World Trade Center towers, WTC 1 and 2), the NIST investigation team said that “while the partial or total collapse of a tall building due to fires is a rare event, we strongly urge building owners, operators and designers to evaluate buildings to ensure the adequate fire performance of the structural system. Of particular concern are the effects of thermal expansion in buildings with one or more of the following features: long-span floor systems, connections not designed for thermal effects, asymmetric floor framing and/or composite floor systems.” Engineers, the team said, should be able to design cost-effective fixes to address any areas of concern identified by such evaluations.

    The investigators also reported that if the city water main had not been cut by the collapse of World Trade Center towers 1 and 2 (WTC 1 and WTC 2), operating sprinklers in WTC 7 would likely have prevented its collapse. “Nevertheless,” Sunder said, “we recommend that building standards and codes be strengthened beyond their current intent to achieve life safety by preventing structural collapse even during severe fires like this one, when sprinklers do not function, do not exist or are overwhelmed by fire.”

    Sunder identified several existing, emerging or even anticipated capabilities that could have helped prevent WTC 7’s collapse. He cautioned that the degree to which these capabilities improve performance remains to be evaluated. Possible options for developing cost-effective fixes include:
    • More robust connections and framing systems to better resist effects of thermal expansion on the structural system.
    • Structural systems expressly designed to prevent progressive collapse, which is the spread of local damage from a single initiating event, from element to element, eventually resulting in the collapse of an entire structure or a disproportionately large part of it. Current model building codes do not require that buildings be designed to resist progressive collapse.
    • Better thermal insulation (i.e., reduced conductivity and/or increased thickness) to limit heating of structural steel and to minimize both thermal expansion and weakening effects. Insulation has been used to protect steel strength, but it could be used to maintain a lower temperature in the steel framing to limit thermal expansion.
    • Improved compartmentation in tenant areas to limit the spread of fires.
    • Thermally resistant window assemblies to limit breakage, reduce air supply and retard fire growth.
    The 12 recommendations reiterated from the WTC towers investigation address several areas, including specific improvements to building standards, codes and practices; changes to, or the establishment of, evacuation and emergency response procedures; and research and other appropriate actions needed to help prevent future building failures.

    Determining the probable collapse sequence for WTC 7, NIST found that the impact of debris from the collapse of WTC 1 ignited fires on at least 10 floors of WTC 7, and the fires burned out of control on six lower floors. The heat from these uncontrolled fires caused thermal expansion of the steel beams on the lower floors of the east side of WTC 7, damaging the floor framing on multiple floors. Eventually, a girder on Floor 13 lost its connection to a critical interior column that provided support for the long floor spans on the east side of the building. The displaced girder and other local fire-induced damage caused Floor 13 to collapse, beginning a cascade of floor failures down to the fifth floor. Many of these floors had already been at least partially weakened by the fires in the vicinity of the critical column. This collapse of floors left the critical column unsupported over nine stories.

    “When this critical column buckled due to lack of floor supports, it was the first domino in the chain,” Sunder explained. “What followed in rapid succession was a progression of structural failures. Failure first occurred all the way to the roof line—involving all three interior columns on the most eastern side of the building. Then, progressing from east to west across WTC 7, all of the columns in the core of the building failed. Finally, the entire façade collapsed.”


    Diagram 1—Typical WTC 7 floor showing locations of columns (numbered). The buckling of Column 79 was the initiating event that led to the collapse of WTC 7. The buckling resulted from fire-induced damage to floors around Column 79, failure of the girder between Columns 44 and 79, and cascading floor failures. [Download high-res version]

    The investigation team considered the possibility of other factors playing a role in the collapse of WTC 7, including the possible use of explosives, fires fed by the fuel supply tanks in and under the building, and damage from the falling debris of WTC 1.

    The team said that the smallest blast event capable of crippling the critical column would have produced a “sound level of 130 to 140 decibels at a distance of half a mile,” yet no noise this loud was reported by witnesses or recorded on videos.

    As for fuel fires, the team found that they could not have been sustained long enough, could not have generated sufficient heat to fail a critical column, and/or would have produced “large amounts of visible smoke” from Floors 5 and 6, which was not observed.

    Finally, the report notes that “while debris impact from the collapse of WTC 1 initiated fires in WTC 7, the resulting structural damage had little effect in causing the collapse of WTC 7.”

    The investigation team found that the design of WTC 7 was generally consistent with the New York City building code in effect at the time. The estimated 4,000 occupants of WTC 7 on the morning of Sept. 11 were evacuated without any fatalities or serious injuries.

    To reach the conclusions in its report, NIST complemented its in-house expertise with private-sector technical experts; accumulated an extensive collection of documents, photographs and videos related to the WTC events of 9/11; conducted first-person interviews of WTC 7 occupants and emergency responders; analyzed the evacuation and emergency response operations in and around WTC 7; and performed the most complex computer simulations ever conducted to model a building’s response behavior and determine its collapse sequence due to a combination of debris impact damage, fires and a progression of structural failures from local fire-induced damage to collapse initiation, and, ultimately, to global collapse.

    NIST welcomes comments on the draft report and recommendations—available online at http://wtc.nist.gov—received by noon Eastern Daylight Time on Sept.15, 2008. Comments (instructions for submission are available at http://wtc.nist.gov) may be submitted via:
    • e-mail to wtc@nist.gov;
    • fax to (301) 869-6275; or
    • surface mail to WTC Technical Information Repository, Attn: Stephen Cauffman, NIST, 100 Bureau Dr., Stop 8611, Gaithersburg, Md. 20899-8610.
    The NIST investigation of WTC 7 was conducted under the National Construction Safety Team (NCST) Act, as part of its overall building and fire safety investigation of the World Trade Center disaster. The act gives NIST the responsibility for conducting fact-finding investigations of building failures that resulted in substantial loss of life or that posed significant potential of substantial loss of life. NIST has no regulatory authority under the NCST Act.

    As an agency of the U.S. Department of Commerce, NIST promotes U.S. innovation and industrial competitiveness by advancing measurement science, standards and technology in ways that enhance economic security and improve our quality of life.
    No One Knows Everything. Only Together May We Find The Truth JG


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    Feds say fires downed building next to twin towers

    http://ap.google.com/article/ALeqM5i...8_BvgD92MPC580

    By DEVLIN BARRETT – 15 minutes ago

    GAITHERSBURG, Md. (AP) — Federal investigators issued a report Thursday concluding that fires brought down a skyscraper next to New York's twin towers on Sept. 11, refuting conspiracy theorists who have long believed that explosives somehow caused the collapse.

    Scientists with the National Institute of Standards and Technology say their three-year investigation of the collapse of the 47-story World Trade Center 7 was the first known instance of fire causing the total failure of a skyscraper.

    The investigators also concluded that the collapse of the nearby towers broke the city water main, leaving the sprinkler system in the bottom half of the building without water.

    The structure has been the subject of a wide range of conspiracy theories for the last seven years, partly because the collapse happened about seven hours after the twin towers were felled. That fueled theories that something else might have caused the collapse.

    Dr. Shyam Sunder, the lead investigator on the project, said his team investigated the possibility that an explosion inside the building brought it down, but found there was no large boom or other noise that would have occurred with such a detonation.

    Investigators also concluded there was no evidence that the collapse was caused by fires from a substantial amount of diesel fuel that was stored in the building.

    The 77-page report concluded that the weakening of a critical steel support column led the rest of the building to fall apart.

    "When this critical column buckled due to lack of floor supports, it was the first domino in the chain," said Sunder.

    The NIST investigators issued more than a dozen building recommendations as a result of their inquiry, most of which repeat earlier recommendations from their investigation into the collapse of the two large towers.

    In both instances, investigators concluded that extreme heat caused some steel beams to lose strength, causing further failures throughout the buildings until the entire structure succumbed.

    The recommendations include building skyscrapers with stronger connections and framing systems to resist the effects of thermal expansion, and structural systems designed to prevent damage to one part of a building from spreading to other parts.
    No One Knows Everything. Only Together May We Find The Truth JG


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    No One Knows Everything. Only Together May We Find The Truth JG


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    As federal agency declares 'new phenomenon' downed WTC 7, activists cry foul

    http://rawstory.com/news/2008/BREAKI...y_on_0821.html

    Stephen C. Webster
    Published: Thursday August 21, 2008

    According to a federal agency report released Thursday, a "new phenomenon" known as thermal expansion was directly responsible for the mysterious collapse of World Trade Center 7 on Sept. 11, 2001.

    This study, posed by the National Institute of Standards and Technology -- a federal scientific agency which promotes technical industrial standards -- marks the first 'official' government theory on the collapse.

    The building's demise occurred some seven hours after the twin towers collapsed on Sept. 11, 2001, and has been the source of numerous conspiracy theories key to the "9/11 Truth" movement, most of which argue that the symmetrical, seven-second collapse was brought about by a controlled demolition.

    Dr. Shyam Sunder, director of Institute's building and fire research laboratory, oversaw the government's three-year research efforts. The report aims to disprove the controlled demolition argument.

    However, Richard Gage, founder of Architects & Engineers for 9/11 Truth and a member of the American Institute of Architects, doesn't believe a word of the theory.

    His group, which has swelled to over 400 architectural and engineering professionals, immediately responded to the Institute's claim in a press conference.

    "Tons of [molten metal] was found 21 days after the attack," said Gage in an interview with a Vancouver, Canada television station. "Steel doesn't begin to melt until 2,700 degrees, which is much hotter than what these fires could have caused."

    "There are holes in this story that you can drive a truck through," Gage added during the press conference. His group asserts that thermite, a steel cutting agent, was used to bring the building down.

    Dr. Sunder disagreed.

    "We conducted the study without bias, without interference from anyone," said Dr. Sunder. "We have only one single-minded goal in this effort."

    While the Institute said it considered the possibility of a controlled demolition taking place at WTC 7, the notion was dismissed due to the absence of any recordings of an explosion sound.

    Thermite, however, does not make an explosion sound. And while this was raised to Dr. Sunder in the media's Q&A session, he dismissed it as impossible.

    "FEMA found it," said Gage. "Dr. Steven Jones found it, in the dust that landed in the entire area of lower Manhattan. And he finds it in the chunks of previously molten metal [from the towers]."

    Specifically, in Appendix C of its World Trade Center Building Performance Study, FEMA claimed:
    Evidence of a severe high temperature corrosion attack on the steel, including oxidation and sulfidation with subsequent intergranular melting, was readily visible in the near-surface microstructure. A liquid eutectic mixture containing primarily iron, oxygen, and sulfur formed during this hot corrosion attack on the steel... The severe corrosion and subsequent erosion of Samples 1 and 2 are a very unusual event. No clear explanation for the source of the sulfur has been identified.
    Yet, no study of the mysterious sulfur or melted steel was included in the NIST report.

    After New York City officials cut off the water main to the tower Sept. 11, 2001, the building's sprinkler system was unable to function, Dr. Sunder said. This allowed fires across 10 floors to burn uncontrolled for nearly seven hours.

    The Institute asserts that due to the lack of water supply, an “extraordinary event” occurred, and for the first time ever, steel expanding due to heat from the flames caused columns to separate from structural concrete. Column 79 was the first to fail, according to the report, which brought about a quick succession of failures in adjoining columns.

    "Thermal expansion of long-span floor systems" was a critical element in the collapse, said Dr. Sunder. The "kink" seen in the building's penthouse portion in video of the collapse was in-line with the columns which failed first.

    "If water had been available, it is likely that sprinklers would have operated and the building may still be here today," he said.

    "It looks like they want to wrap-up this investigation and blame [the collapse] on normal office fires," said Gage during counter-conference.

    WTC 7's structural system is in "widespread use" in other buildings, he added, insisting that such effects may also be present elsewhere. The Institute's report also includes recommendations for the strengthening of building codes to avoid future thermal expansion-driven collapses.

    The collapse of WTC 7 is "no longer a mystery," Dr. Sunder claimed.

    The Institute's full report is available at wtc.nist.gov.

    Further details from the Architects & Engineers for 9/11 Truth press conference are forthcoming.
    No One Knows Everything. Only Together May We Find The Truth JG


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    Report Says Fire, Not Explosion, Felled 7 W.T.C.

    http://www.nytimes.com/2008/08/22/ny...in&oref=slogin

    By ERIC LIPTON
    Published: August 21, 2008

    GAITHERSBURG, Md. — Fires in the 47-story office tower at the edge of the World Trade Center site undermined floor beams and a critical structural column, federal investigators concluded on Thursday, as they attempted to curb still-rampant speculation that explosives caused the building’s collapse on Sept. 11, 2001.

    No one died when the tower, 7 World Trade Center, tumbled, as the estimated 4,000 office workers there at the time had evacuated before it gave way, nearly seven hours after the second of the twin towers came down.

    But the collapse of 7 World Trade Center — home at the time to branch offices of the Central Intelligence Agency, the Secret Service and the Giuliani administration’s emergency operations center — is cited in hundreds of Web sites and books as perhaps the most compelling evidence that an insider secretly planted explosives, intentionally destroying the tower.

    A separate, preliminary report issued in 2002 by the Federal Emergency Management Agency questioned whether diesel fuel tanks installed in the tower to supply emergency generators — including one that powered the Giuliani administration’s emergency “bunker” — might have been to blame.

    But Shyam Sunder, the lead investigator from the National Institute of Standards and Technology, based here in suburban Washington, also rejected that theory on Thursday, even as he acknowledged that the collapse had been something of a puzzle.

    “Our take-home message today is the reason for the collapse of World Trade Center 7 is no longer a mystery,” Dr. Sunder said at a news conference at the institute’s headquarters. “It did not collapse from explosives or fuel oil fires.”

    The institute’s findings were released on Thursday as part of a 915-page report resulting from the work of more than 50 federal investigators and a dozen contractors over three years.

    Conspiracy theorists have pointed to the fact that the building fell straight down, instead of tumbling, as proof that that explosives were used to topple it, as well as to bring down the twin towers. A Scripps Howard/Ohio University poll suggested that as many as one in seven Americans believed that theory.

    During the last four decades, other towers in New York, Philadelphia and Los Angeles have remained standing through catastrophic blazes that burned out of control for hours because of malfunctioning or nonexistent sprinkler systems. But 7 World Trade Center, which was not struck by a plane, is the first skyscraper in modern times to collapse primarily as a result of a fire. Adding to the suspicion is the fact that in the rush to clean up the site, almost all of the steel remains of the tower were disposed of, leaving investigators in later years with little forensic evidence.

    Using videos, photographs and building design documents, the investigators at the National Institute spent the last three years building an elaborate computer model of 7 World Trade Center that they used to test various chains of events to figure out what caused the collapse, Dr. Sunder said.

    The investigators determined that debris from the falling twin towers damaged structural columns and ignited fires on at least 10 floors at 7 World Trade Center, which stood about 400 feet north of the twin towers. But the structural damage from the falling debris was not significant enough to threaten the tower’s stability, Dr. Sunder said.

    The fires on six of the lower floors burned with particular intensity because the water supply for the sprinkler system had been cut off — the upper floors had a backup water supply — and the Fire Department, devastated by the collapse of the twin towers, stopped trying to fight the blaze.

    Normally, fireproofing on a skyscraper should have been sufficient to allow such a blaze to burn itself out and leave the building damaged but still standing. But investigators determined that the heat from the fire caused girders in the steel floor of 7 World Trade Center to expand. As a result, steel beams underneath the floors that provided lateral support for the tower’s structural columns began to buckle or put pressure against the vertical structural columns.

    These fires might have been fed partly by the diesel from tanks and a pressurized fuel line, which were on the fifth to the ninth floors, Dr. Sunder said. But the analysis showed that even in the worst case, the diesel fuel-fed fire would not have burned hot enough or long enough to have played a major role in weakening the structure. The investigators determined that the fire that day was fed mainly by office paper and furnishings.

    The collapse started when a girder on the 13th floor disconnected from a critical column — listed as Column 79 — that supported a long open floor span, the report said. Once that floor gave way, the floors below it down to the fifth floor also collapsed, although this was not visible from the building’s exterior.

    Without lateral support for nine stories, Column 79 buckled, and the floors above gave way all the way up to the roof. Only then did the collapse become visible from the exterior with a penthouse area on the roof first falling in, followed by what looked like the sudden implosion of the tower, Dr. Sunder said.

    “The physics is consistent, it is sound, it has been analyzed,” he said.

    Skeptics have questioned whether explosives were planted at the three towers at ground zero, as at well the Pentagon, often contending that the Bush administration had planned the catastrophes to provide a justification to invade Iraq and Afghanistan. What started as a small number of such conspiracy theorists ballooned into a movement of sorts, largely fed by Internet sites and homemade videos.

    Dr. Sunder said the investigators considered the possibility that explosives were used, but ruled it out because the noise associated with such an explosion would have been 10 times louder than being in front of the speakers at a rock concert, he said, and detectable from as far as a half a mile away. He said that interviews with eyewitnesses and a review of video taken that day provided no evidence of a sound that loud just before the collapse.

    The skeptics — including several who attended Thursday’s news conference — were unimpressed. They have long argued that an incendiary material called thermite, made of aluminum powder and a metal oxide, was used to take down the trade center towers, an approach that would not necessarily result in an explosive boom. They also have argued that a sulfur residue found at the World Trade Center site is evidence of an inside job.

    Dr. Sunder said the investigators chose not to use the computer model to evaluate whether a thermite-fueled fire might have brought down the tower, since 100 pounds of it would have had to have been stacked directly against the critical column that gave way, which he said they did not believe had occurred.

    To the skeptics, it was a glaring omission.

    “It is very difficult to find what you are not looking for,” said Shane Geiger, one who had come to Maryland from Texas to quiz Dr. Sunder about his findings, with a bumper sticker on his laptop computer that says, “9-11 was an inside job.”

    Dr. Sunder attempted to patiently answer the questions that Mr. Geiger and another obvious critic presented to him during the news conference. Five armed police officers and a bomb-sniffing dog stood guard near the rear of the room.

    Dr. Sunder said there were no apparent flaws in 7 World Trade Center’s design that contributed to its collapse and that it met New York City codes. But there are some important lessons for other skyscrapers, he said, as engineers and architects should consider how the heat from fires can cause structural elements, potentially causing a so-called progressive collapse.

    Owners of tall buildings with a similar floor design — he could not estimate how many such towers exist in the United States — should immediately consider whether to install reinforcements, he said, and perhaps codes should be changed to address the weakness.

    A new, substantially different 7 World Trade Center — now 52 stories — reopened at roughly the same site in 2006. The new building has a number of extra safety features, including wider emergency stairwells and a fire-resistant refuge area on each floor.

    Within moments after the news conference ended, leaders of a group called Architects and Engineers for 9/11 Truth held their own telephone conference briefing, dismissing the investigation as flawed.

    “How much longer do we have to endure the cover up of how Building 7 was destroyed?” said Richard Gage, a California architect and leader of the group.

    Told of the doubts, Dr. Sunder said he could not explain why the skepticism would not die.

    “I am really not a psychologist,” he said. “Our job was to come up with the best science.”
    No One Knows Everything. Only Together May We Find The Truth JG


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    6 Debunked 9/11 Conspiracy Claims From Today's NIST Report

    http://www.popularmechanics.com/scie...h/4278927.html

    By Arianne Cohen
    Published on: August 21, 2008

    GAITHERSBURG, MD. — Shyam Sunder, the lead investigator on the National Institute of Standards and Technology (NIST) report, responded directly to many conspiracy claims here this morning at his press conference in NIST headquarters in Gaithersburg, Md., which was attended by mainstream media and a handful of conspiracy theorist media, including a representative from InfoWars.com, a Web site that puts forward 9/11 conspiracy theories. Sunder specifically addressed conspiracy claims linked to WTC 7. "Before I tell you what we found, I'd like to tell you what we did not find," Sunder told reporters. "We did not find any evidence that explosives were used to bring the building down. The collapse was also not due to fires from the substantial amount of diesel fuel stored in the buildings."

    Here is a summary of some common 9/11 conspiracy theory claims regarding WTC 7, along with NIST's response:

    Claim: "No combination of debris damage, fuel-tank explosions and fires could inflict the kind of simultaneous damage to all the building's columns required to make the building implode," says WTC7.net, a Web site dedicated to conspiracy theories. "The precision of such damage required to bring Building 7 down into its footprint was especially great, given the ratio of its height to its width and depth."

    NIST report and press conference: Fire did indeed inflict enough column damage to destroy the building through a previously undocumented collapse sequence of thermal expansion. "Anyone who has run a tight jar lid under water to help loosen it knows that the metal expands when it gets hot," Sunder said. "Heat also causes steel to lose strength and stiffness. Thermal expansion occurs at temperatures much lower than those required to reduce steel strength and stiffness." The report found that as WTC 7's steel beams expanded in the heat, numerous structural connections throughout the building failed. That weakened the structure even before the collapse of any vertical columns.

    Claim: The shape of the building's tidy pile of wreckage is consistent with a demolition, conspiracy theorists say.

    NIST report and press conference: Sunder agrees that the wreckage was tidy and explained why. "If you look at columns 79, 80 and 81 [three of the building's central columns], the floor area that they're carrying is very large—particularly column 79, which was carrying about 2000 sq. ft. of floor area." Column 79 was the first column to fail. "It was an interior column that failed, followed by two more interior columns [80 and 81], then east to west. So what you're seeing is an interior collapse, then to the outside. What you're getting is an impression of a controlled demolition, but it's not."

    Claim: The way the building fell was caused by demolition or thermate. (Thermate is thermite mixed with sulfur and sometimes other chemicals, which produces brief but intense and highly localized incendiary effects.)

    NIST report and press conference: Sunder said that his team investigated these hypothetical causes and ruled them out. "We asked ourselves what is the minimum amount of charge we could use to bring the building down," he said. "And we found that even the smallest charge would release an extremely loud sound heard half a mile away." There were no reports of such a sound; numerous observers and video recordings found the collapse to be relatively quiet.

    Prominent conspiracy theorist Steven Jones and others have suggested that thermate could have been inserted into a column, exploding the column without the loud boom of a demolition. Sunder said his team considered that theory. "In order for the thermate reaction to melt steel to take place, there has to be materials. If you look at the amount needed—at least 100 pounds for one column—you need someone to get that amount in the building, and place it, and for the reaction to take place. It is unlikely."

    Claim: At the press conference, theorists questioned why NIST had just now found a previously undocumented cause of building collapse.

    NIST report and press conference: The particulars of WTC 7's design contributed to the thermal expansion. WTC 7 had floor spans up to 54 ft. long. "Longer beams can be subject to proportionally greater expansion effects," Sunder noted. "Other tall buildings have burned for as long or longer in similar fires without collapsing—when sprinklers either did not exist or were not functional. So we knew from the beginning of our study that understanding what happened to Building 7 on 9/11 would be difficult. It did not fit any textbook description that you could readily point to and say, yes, that's why the building failed." The issue, Sunder said, was that buildings are not typically tested for their structural response to fire.

    Claim: The minimal wreckage available for later investigation has generated speculation. Some conspirators point to the fast removal of debris as evidence of a government coverup.

    NIST report and press conference: Compared to WTC 1 and 2, NIST had very little WTC 7 wreckage to study. The site was cleared quickly in a search-an- rescue effort, and much of the debris was transported to salvage yards. "There was no loss of life," Sunder noted. "In hindsight, we knew that the building was evacuated. But we didn't know that on that day." Hundreds of investigators at the salvage yards later found that the Twin Towers' steel columns were labeled and numbered, while the columns from Towers 5, 6 and 7 were not. "I am not surprised that there wasn't a lot of identifiable debris," Sunder said. "But at the time, we were concerned about terrorists who attacked our country and search and rescue. I think the fact that they [invesigators] didn't collect [wreckage] was the least important activity that happened that day."

    Claim: Many theorists have suggested that the long delay in an explanatory report is further proof of a government coverup.

    NIST and press conference: NIST first had to complete the investigation on the collapse of the Twin Towers and publish its report before turning to WTC 7. The Twin Towers report was released in September 2005. "We thought we might be able to do things much quicker and faster because of our tower experience," Sunder said. "I think we underestimated the amount of effort that would be required to answer the questions that we raised." In addition, new computer models of the collapse had to be created. "A typical fire simulation for a single floor of the building took up to two days with a state-of-the-art cluster of Linux computers. We had computer programs that took six to eight months to get a correct run, and we wanted to make sure we got this right. And three years is not an unusual length of time." Sunder emphasized that previous reports were preliminary and provisional. "We didn't have the insight that thermal expansion could have happened until early last year," Sunder said. "After that it was smooth sailing." Until last year, NIST was still investigating other hypotheses, including whether the building's location on top of an electric substation played a critical role and whether 6000 gal. of diesel fuel used to power backup generators in the building directly weakened the columns. Both hypotheses were abandoned.

    Sunder classified the report's conclusions as "simple, straightforward, elegant and going along with what was observed. I would say that the findings we have are incredibly conclusive that fire is why WTC 7 collapsed."
    No One Knows Everything. Only Together May We Find The Truth JG


  10. #10
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    Fire caused collapse of World Trade Center 7: probe

    http://afp.google.com/article/ALeqM5...psTpGQ-ORg_Uqw

    1 hour ago

    NEW YORK (AFP) — A raging, long-burning fire caused the collapse of World Trade Center building number 7, which tumbled hours after hijacked jets hit the twin towers on September 11, 2001, investigators said Thursday.

    The National Institute of Standards and Technology (NIST) found that the 47-story building, which stood right next to towers 1 and 2, caught fire due to the debris that flew into it after the planes struck.

    It eventually fell after seven hours due to instability caused by the fire, not by explosives as some conspiracy theorists have claimed.

    "Our study found that the fires in WTC 7, which were uncontrolled but otherwise similar to fires experienced in other tall buildings, caused an extraordinary event," said lead investigator Shyam Sunder.

    "Heating of floor beams and girders caused a critical support column to fail, initiating a fire-induced progressive collapse that brought the building down," he said.

    "Video and photographic evidence combined with detailed computer simulations show that neither explosives nor fuel oil fires played a role in the collapse of WTC 7."

    He said debris from tower 1 sparked the blaze on at least 10 floors of the building, which burned for about seven hours while some of its sprinkler systems were non-operational due to a city water main cut.

    "We did not find any evidence that explosives were used to bring the building down," he said.

    "This size blast would have produced an incredibly loud sound that was not recorded on videos of the collapse nor reported by witnesses."

    He added that the "collapse was also not due to fires from the substantial amount of diesel fuel stored in the building."

    A team of 50 experts from diverse fields, including engineering, explosives, fire, and construction took part in the probe.

    The September 11 attacks on New York killed nearly 3,000 people.
    No One Knows Everything. Only Together May We Find The Truth JG


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