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Buildings
Forensic Expert Studying WTC Steel
(architecturalrecord.com-
01/10/02)
By Deborah Snoonian, P.E.
Abolhassan Astaneh-Asl, P.E., a forensics
expert and structural engineering professor at the University of
California at Berkeley, is studying the World Trade Center disaster
with the goal of improving skyscraper design. Using a grant from
the National Science Foundation, Astaneh-Asl will test damaged steel
from several portions of the towers and build a computer model,
in conjunction with Lawrence Livermore National Laboratory in Livermore,
California, to simulate the crashes, fires, and collapses. The lab
has the computing power needed to recreate the disaster digitally.
By varying model parameters such as column design, construction
materials, and type of fireproofing, Astaneh-Asl hopes to find ways
to harden future buildings against catastrophic failure.
Last September, Astaneh-Asl was part of a team from the American
Society of Civil Engineers that convinced the city of New York to
delay recycling the WTC steel so that some of it could be studied
for clues to the collapses. At a scrapyard in Jersey City he has
helped identify the steel pieces to be saved.
The most important structural steel members to study are those
severed by the planes and those that sustained the heaviest fire
damage. The severed members will be studied to determine the speed
and force of impact. Fire-damaged steel will be examined under an
electron microscope for changes to its crystal structure; material
scientists can then determine how long fires burned and at what
temperature the steel failed.
Astaneh-Asl will also study structural members relatively unaffected
by the crash or fires. “There were lots of different types
of steel used in the towers—both high- and regular-strength—and
we can learn things from pieces that fell hundreds of feet as the
buildings collapsed,” he explains. Tests can measure the robustness
of bolts and connections, for example, and identify the types of
steel adequate for various structures.
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