Collapse of the World Trade Center Towers. Final Report. Federal Building and Fire Safety Investigation of the World Trade Center Disaster.
Collapse of the World Trade Center Towers. Final
Report. Federal Building and Fire Safety Investigation
of the World Trade Center Disaster.
(8965 K)
National Institute of Standards and Technology; National
Construction Safety Team
NIST NCSTAR 1; 298 p. September 2005.
Order number: PB2006-100819
Keywords:
World Trade Center; high rise buildings; building
collapse; disasters; terrorists; terrorism; fire
investigations; fire safety; reconstruction; occupants;
aircraft jet fuels; damage; impact; building codes; fire
codes; building design; fire protection; steel
structures; concretes; structures; aircraft impact;
mapping; fire resistance; floors; first responders; life
safety; regulations; evacuation; simulation; temperature
Abstract:
This is the final report on the National Institute of
Standards and Technology (NIST) investigation of the
collapse of the World Trade Center (WTC) towers,
conducted under the National Construction Safety Team
Act. This report describes how the aircraft impacts and
subsequent fires led to the collapse of the towers after
terrorists flew jet fuella,den commercial airliners into
the buildings; whether the fatalities were low or high,
including an evaluation of the building evacuation and
emergency response procedures; what procedures and
practices were 11sed in the design, construction,
operation, and maintenance of the towers; and areas in
current building and fire codes, standards, and
practices that warrant revision. Extensive details are
found in the 42 companion report.s. The final report on
the collapse of WTC 7 will appear in a separate report.
Also in this report is a description of how NIST reached
its conclusions. NIST complemented in-house expertise
with private sector technical experts; accumulated
copious documents, photographs, and videos of the
disaster; established baseline performance of the WTC
towers; performed computer simulations of the behavior
of each tower on September 11, 2001; combined the
knowledge gained into a probable collapse sequence for
each tower; conducted nearly 1,200 first-person
interviews of building occupants and emergency
responders; and analyzed the evacuation and emergency
response operations in the two high-rise buildings. The
report concludes with a list of 30 recommendations for
action in the areas of increased structural integrity,
enhanced fire endurance of structures, new methods for
fire resistant design of structures, enhanced active
fire protection, improved building evacuation, improved
emergency response, improved procedures and practices,
and education and training.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899