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Buildings
No Reasonable Precautions Could Have Prevented Collapses
(enr.com
- 4/08/02 issue)
By Nadine Post
A draft copy of an unpublished building performance
study of the collapse of the World Trade Center towers cites their
"design and construction characteristics" as key to their
ability to withstand immediate failure after two hijacked airliners
slammed into them. The Sept. 11 collapse was caused by the combination
of the attack and resulting fires.
The study is to be released by the American
Society of Engineers and the Federal Emergency Management Agency
by early May. It was obtained and portions published by the New
York Times. "The ability of the two towers to withstand
aircraft impact without immediate collapse was a direct function
of their design and construction characteristics, as was the vulnerability
of the two towers to collapse as a result of the combined effects
of the impacts and ensuing fires," according to the draft.
"The first federal assessment of the
trade center disaster...has made clear that there may have been
no reasonable precautions that could have stopped the towers from
collapsing once they were struck and huge fires broke out,"
says the Times.
The draft report confirms that fireproofing, fire suppression systems
and water supply for hoses were disabled. It also says that the
blaze triggered by plane fuel was so intense that it "drove
temperatures as high as 2,000° F and generated heat equivalent
to the energy output of a nuclear powerplant."
Neither ASCE or FEMA would comment before the final report is released.
Last week, FEMA and the National Institute of Standards and Technology,
Gaithersburg, Md., issued a statement that the two entities have
entered into a memorandum of understanding that designated NIST
to serve "as a research and technical resource" for FEMA.
The agreement, intended to "support the federal government's
capabilities to reduce national disaster losses and enhance homeland
security," was in the works before Sept. 11. "It was just
pushed to the forefront by the World Trade Center," says Michael
Newman, a NIST spokesman. The agreement gives NIST the ability to
be called into play by FEMA sooner, he adds.
Among other plans, NIST and FEMA will implement a process fo "plan,
prioritize, select and fund projects...in fire, disaster prevention
and homeland security."
There is no money involved in the agreement. However, NIST expects
$16 million from FEMA's homeland security appropriation, now before
Congress, for a two-year technical study into the post-attack performance
of the trade center.
NIST is already planning to begin the study, though Newman says
there is no way of knowing how fast funds will become available.
Some 60 pieces of steel likely to reveal information on the sequence
of events were set aside at scrap yards by the members of the Structural
Engineers Association of New York and are in storage at NIST.
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