A Memorial Lecture on the Engineering Aspects of the World Trade Center Collapse - Livestream

First, this Memorial lecture honors the memories of the victims of the tragic and criminal terrorist attacks on the World Trade Center towers on September 11, 2001, as well as pays tribute to the first responders, the firefighters, EMTs, and police officers, who so heroically sacrificed their lives to save others. Second, the lecture focuses on the engineering aspects of the tragic collapse of the World Trade Center. Dr. Astaneh, with a grant from the National Science Foundation flew to New York a week after the tragic 9/11 attacks, when the flights to New York resumed, and conducted the reconnaissance and investigation of the collapsed WTC towers. In May of 2002, he testified before the Committee on Science of the House of Representative as part of World Trade Center Public Hearings. Subsequently provided with unique access to all the plans and structural drawings of the WTC, he worked for the next six years with his team of volunteer engineers and Berkeley students, performing a detailed and extensive nonlinear finite element analysis of the impact of the planes on the towers.

His team’s investigation revealed that the World Trade Center towers were constructed using an unusual structural system called steel "Bearing Walls", where the weight of the building was given to relatively thin stiffened steel plate bearing walls on the outside and steel columns on the inside that were connected to the outside walls with steel truss joists instead of the usual vertical columns and horizontal beams connected to each other with sturdy connections. The investigation showed that from an engineering point of view, the main cause of the collapse was due to the use of this unusual steel "bearing wall" system, very vulnerable to impact and fire. The study also showed that had the structure been designed using a traditional beam and column configuration following the governing design codes instead of the unusual steel bearing wall system, the damage would have been limited to localized failure, and the towers most likely would not have collapsed.

Speaker: Albolhassan Astaneh-Asl, Professor Emeritus of Structural Engineering, UC Berkeley

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