CONSTRUCTION INNOVATION  Volume 7 Number 1, Winter 2002

Newsbrief - IRC fire researcher on team of experts studying World Trade Center collapse

The Sept. 11 terrorist attacks on the World Trade Center and the Pentagon caused significant damage and destruction to buildings and infrastructure in the vicinity of both complexes. In the aftermath of these attacks, civil engineers have assumed a prominent role and are leading the effort to evaluate not only the performance of the affected buildings but also the vulnerability of buildings and infrastructure in general to future attacks.

The American Society of Civil Engineers (ASCE), together with the Federal Emergency Management Agency (FEMA), has established a team of experts, the Building Performance Assessment Team (BPAT), to investigate the factors that led to the collapse of and damage to the World Trade Center towers and other buildings around them (see box below). The team will also identify and make recommendations on further research that needs to be done as a consequence of the terrorist attacks.

The BPAT team is made up of experts in tall buildings, steel structures, connections, fire engineering, blast effects, and structural investigations.

Dr. Venkatesh Kodur, a research officer at NRC's Institute for Research in Construction and a leading world expert on the fire resistance of building materials, is the only expert from outside the United States invited to join the team.

At the beginning of October, the team visited the collapsed and damaged buildings at Ground Zero and over a period of six days collected a significant amount of data on building performance under extreme conditions. It is now in the process of analyzing this data to determine which parts of the buildings and, specifically, which columns were destroyed on initial impact, and how the fire grew and contributed to the collapse of the towers and the surrounding buildings.

Findings from the study will be published in Spring 2002 in a joint ASCE/FEMA report. Further details can be found on the ASCE's Web site at http://www.asce.org/emerg_document_pub.cfm.

Damage to the WTC and surrounding buildings
Significant damage occurred in the seven buildings of the WTC complex and to a number of high-rise buildings around the WTC (within a radius of about one kilometre):

• 4 buildings (Towers 1 and 2, Buildings 3 and 7 of the WTC) completely collapsed
• 4 buildings around the towers partially collapsed (beyond repair)
• 9 buildings incurred major structural damage
• 18 other buildings experienced minor damage
• 400 high-rise buildings required full structural assessment

The BPAT team represents a coalition of leading engineering organizations brought together and led by ASCE and FEMA, including the American Institute of Steel Construction Inc. (AISC), the American Concrete Institute (ACI), the Council on Tall Buildings and Urban Habitat (CTBUH), the International Code Council (ICC), the National Fire Protection Association (NFPA), the Society of Fire Protection Engineers (SFPE), the Structural Engineers Association of New York (SEAoNY), the Masonry Society (TMS), the National Council of Structural Engineers Associations (NCSEA), the Structural Engineering Institute (SEI) of the ASCE, and the New York Department of Design and Construction (DDC).