COMMITTEE ON SCIENCE
U.S. HOUSE OF REPRESENTATIVES
Learning from 9/11: Understanding the Collapse of the World Trade Center
At the same time, the
FEMA Building Performance Assessment Team (BPAT) began their important work of initiating an analysis that
could ultimately yield valuable information about the sequence of events and failures that resulted in
progressive building collapse.
BPATs are routinely deployed by FEMA following disasters caused by
events such as floods and hurricanes. The teams are formed by, and operate under the direction of the
Mitigation Directorate’s Program Assessment and Outreach Division and comprise such individuals as regional
FEMA staff, representatives from state and local governments, consultants who are experts in engineering,
design, construction, and building codes, and other technical and support personnel. A contractor for FEMA,
Greenhorne & O’Mara, Inc., maintains a roster of hundreds of mitigation specialists from across the United
States. BPAT teams are typically deployed within seven days of any disaster event.
Generally, a BPAT
conducts field inspections and technical evaluations of buildings to identify design practices, construction
methods, and building materials that either failed or were successful in resisting the forces imposed by the
event. A major objective of the BPAT’s findings and recommendations are aimed at improving design,
construction and enforcement of building codes to enhance performance in future disasters. The culmination of
the BPAT’s efforts is a report that presents the team’s observations, conclusions, and recommendations for
improving building performance in future natural disasters.
The BPAT team deployed to the WTC site
was assembled by the American Society of Civil Engineers and is headed by W. Gene Corley, Ph.D., P.E, Senior
Vice President of Construction Technologies Laboratory in Skokie, Illinois. He was also the principal
investigator in the FEMA study of Oklahoma City’s Murrah Federal Office Building. On September 11th, ASCE,
in partnership with a number of other professional organizations, commenced the formation of an independent
team of experts to conduct a building performance assessment study at the WTC site as part of ASCE’s Disaster
Response Procedure. In late September, this team, the ASCE Disaster Response team, was officially appointed as
the BPAT team and was funded by FEMA to assess the performance of the buildings and report its findings.
The BPAT team received $600,000 in FEMA funding in addition to approximately $500,000 in ASCE in-kind
The 23-member BPAT team conducted an analysis of the wreckage on-site, at Fresh Kills
Landfill and at the recycling yard from October 7-12, 2001, during which the team extracted samples from
the scrap materials and subjected them to laboratory analysis. Why the analysis was conducted only after a
delay of three weeks after the attacks remains unclear. Since November, members of the Structural
Engineers Association of New York (SEAoNY) have volunteered to work on the BPAT team’s behalf and are visiting
recycling yards and landfills two to three times a week to watch for pieces of scrap that may provide
important clues with regard to the behavior of the buildings.
In the month that lapsed between the
terrorist attacks and the deployment of the BPAT team, a significant amount of steel debris – including most
of the steel from the upper floors – was removed from the rubble pile, cut into smaller sections, and either
melted at the recycling plant or shipped out of the U.S. Some of the critical pieces of steel – including the
suspension trusses from the top of the towers and the internal support columns – were gone before the first
BPAT team member ever reached the site. Fortunately, an NSF-funded independent researcher, recognizing that
valuable evidence was being destroyed, attempted to intervene with the City of New York to save the valuable
artifacts, but the city was unwilling to suspend the recycling contract. Ultimately, the researcher appealed
directly to the recycling plant, which agreed to provide the researcher, and ultimately the ASCE team and the
SEAoNY volunteers, access to the remaining steel and a storage area where they could temporarily store
important artifacts for additional analysis. Despite this agreement, however, many pieces of steel still
managed to escape inspection.
Experts critical of the current [investigation], including some of those people who are
actually conducting it, cite the lack of meaningful financial support and poor coordination with the agencies
cleaning up the disaster site. They point out that the current team of 20 or so investigators has no subpoena
power and little staff support and has even been unable to obtain basic information like detailed blueprints
of the buildings that collapsed. ...
In calling for a new investigation, some structural
engineers have said that one serious mistake has already been made in the chaotic aftermath of the collapses:
the decision to rapidly recycle the steel columns, beams and trusses that held up the buildings. That may have
cost investigators some of their most direct physical evidence with which to try to piece together an answer.
Dr. Frederick W. Mowrer, an associate professor in the fire protection engineering
department at the University of Maryland, said he believed the decision could ultimately compromise any
investigation of the collapses. ''I find the speed with which potentially important evidence has been removed
and recycled to be appalling,'' Dr. Mowrer said. [New York Times
|"Time is short. The piles of high
strength steel evidence are being cut into chunks for export to recycling plants in the Far East. The deals
with the scrap merchants have already been made."|