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Buildings
NIST Not Ruling Anything Out on WTC Probe
enr.construction.com
- 12/09/02
By Tom
Ichniowski
About three months into a two-year investigation of the
World Trade Center disaster, officials at the National Institute of Standards
and Technology say it's too early to rule out any possible scenarios for what
caused the buildings to fall.
At a Dec. 9 briefing, NIST Director Arden Bement said NIST
feels more study is needed to determine which of the various hypotheses about the
WTC collapses is "most probable." Bement adds, "We have concluded that it's too
early to exclude any potential sequence of events between the aircrafts' impact
and the collapse of the WTC towers."
NIST has run a variety of tests so far, including analyses
on some of the more than 200 pieces of WTC steel it now has. Shyam Sunder, NIST's
lead investigator in the WTC probe, says officials have located pieces representing
nine of the 12 steel strengths used in the perimeter columns and nine of the 11
strengths used for the spandrel beams.
Sunder says that about 250 chemical analyses indicate that
most of the perimeter columns are "higher-strength micro-alloyed steels...or
chromium-molybdenum steels that would meet U.S. specifications for heat-resisting
steels." Most of the columns were made from steel from Yawata Steel, which is now
Nippon Steel.
In addition, Sunder says documents from Laclede Steel,
fabricator of the WTC floor trusses, show that steel "routinely met or exceeded
the specified strengths."
Sunder says NIST has had good cooperation from the many
organizations involved in the WTC, including the Port Authority of New York and
New Jersey, Silverstein Properties, insurance companies and New York City agencies.
He says that none of the parties has refused to give NIST any data it requested,
although some information may have been destroyed in the buildings' collapses.
Bement made a request to the public and the media for photos
or video images that could aid NIST's probe. More specifically, NIST is seeking
images of WTC 7 and views from the south and west sides of the two WTC towers.
Bement says, "In particular, there is a dearth of photos of the south side of
WTC 7." That side, some have said, was hit by debris from WTC 1, which may have
started the fires that led to WTC 7's collapse." NIST is asking anyone who has or
knows of such images to contact the agency at wtc@nist.gov or by fax at
(301)975-6122.
Sunder says there may be many such photos or videos that
haven't been shown already on television or published by newspapers and magazines.
"We're not looking for the spectacular photographs," he says, but anything that
sheds light on how the buildings looked during the time from impact to collapse.
In addition, Sunder says that as part of the investigation,
NIST plans to do face-to-face interviews of as many as 600 WTC occupants and
150 first responders.
Sunder says NIST plans to add outside
contractors to supplement its 24-person, in-house WTC team.
He says the agency is looking for "world-class experts" and
will issue the contract notices "in the coming weeks" on its
web site, which is http://wtc.nist.gov.
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