Sept. 11, 2009: Results of World Trade Center Studies by
Abolhassan Astaneh, Jin Son and Casey Heydari
Abstract
The World Trade Center
A Remembrance and the Release of Results
of a 5-Year Structural Engineering Investigation
By: Abolhassan Astaneh-Asl, Ph.D., P.E., (www.astaneh.net)
Professor, University of California, Berkeley
One week after the 9/11/2001 tragedy, started reconnaissance and investigation of the collapsed World Trade Center
towers in New York supported by the National Science Foundation. Later, in May of 2002, I testified before the
Committee on Science of the House of Representatives on my findings and received drawings of the WTC from the
Committee to continue my studies of the WTC structure. Since then, I have led a team of more than 11 highly qualified
volunteer researchers and engineers and have completed the analyses of the impact of various airplanes on the World
Trade Center towers in order to learn lessons from this tragedy that can be used to prevent such catastrophic
collapses and to save lives.
Since the 9/11, each year, I have given a Memorial Lecture on the WTC, remembering the victims and first responders
who so heroically gave their lives to save others, and then providing an update on engineering aspects of the collapse
and reconstruction of the WTC buildings. This year, I am devoting most of the Memorial Lecture to release, for the first
time, the results of our five- year studies of the structural aspects of the WTC design and the collapse. Our 5-year
analysis primarily focused on finding an answer to the question of: “What would have happened if instead of the unusual
and relatively light bearing wall structural system with no framing, used in the WTC towers, a more traditional system of
structural framing used in almost any other structure, was used? Very few people are aware of the fact that the WTC
towers did not need to follow any design code and did not need to obtain the construction permit from the City. The
structural system used in the towers was an unusual system of “Steel Exterior Bearing Walls and Interior Compression
Columns” with no framing system in between. There is no record of use of such a system before or after the design and
construction of the World Trade Center. The issue of structural design of the WTC and its effects on the fate of these
towers on that tragic day has not been studied or reported by other studies of the WTC. The results presented here will
show what would have happened if the towers were designed following the code and using the structural systems used
in almost any other building structure instead of the unique system used in the collapsed WTC towers. |
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