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Fireproofing dismissed as wtc collapse cause { October 19 2004 } Original Source Link: (May no longer be active)
http://www.dallasnews.com/sharedcontent/dws/news/nation/stories/101904dnnat911.6e1ca.htmlhttp://www.dallasnews.com/sharedcontent/dws/news/nation/stories/101904dnnat911.6e1ca.html
Torn fireproofing caused WTC towers' collapse
Concerns of adequate fireproofing dismissed as cause of collapse in government report
06:03 PM CDT on Tuesday, October 19, 2004
Bloomberg News
The World Trade Center likely collapsed because jetliners that slammed into the twin towers knocked fireproofing loose, not because of missing or inadequate fire protection, according to findings released today by U.S. investigators.
The two aircraft disintegrated on impact, sending a wave of debris through each building and igniting them with burning jet fuel. Fires caused steel beams in the buildings' core to shorten, stressing supports built into the towers' facade and pulling them down, the government found.
"Had the fireproofing not been dislodged, the temperature rise of the structural components would likely have been insufficient to cause the global collapse of the towers," the U.S. Commerce Department's National Institute of Standards and Technology said in a press release.
The institute, whose mission includes developing office- building safety standards, is more than two years into an investigation of the 2001 attack on the 110-story twin towers in lower Manhattan by Osama bin Laden's al-Qaeda terrorist group.
A draft of its final report and recommendations for public comment is scheduled for December or January. The press release accompanied a presentation the institute made in Washington today to the National Construction Safety Team Advisory Committee, a panel of building and fire experts that assists the organization in its work.
Questions Raised
Since the attacks destroyed the Trade Center complex, questions have been raised about whether the buildings were properly fireproofed.
Institute investigators reported four months ago that the south tower, which fell 56 minutes after it was struck by a hijacked commercial jet, had less fire protection on its steel than the north tower, which lasted 103 minutes.
The Port Authority of New York and New Jersey, owner of the towers, was in the midst of applying fresh protectant to the entire complex at the time of the attacks, the institute's chief, Sivaraj Shyam-Sunder, said in June.
Areas where fireproofing was knocked off of steel by plane debris was more a factor than "any areas where there was missing or thin fireproofing before the aircraft impacts," today's statement said.
Investigators now believe the south tower fell more quickly because the plane that struck it came in at an angle and pushed debris into a corner of the building, concentrating the damage to fireproofing and the subsequent blaze, Michael Newman, a spokesman for the institute, said in an interview. The plane that penetrated the north tower did so level and in the middle of the structure, spreading the debris more evenly, he said.
The latest information also quantified earlier findings that steel quality probably had nothing to do with the buildings' failure.
Some 87 percent of the recovered specimens tested exceeded required strength, the press release said. While 13 percent did not, "the safety of the towers was most likely not affected by the small percentage of steel below the minimum," the report said. "The structural loads on Sept. 11, 2001, were well below" the buildings' design level.
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