Final Report on the Collapse of World Trade Center Building 7.
Final Report on the Collapse of World Trade Center
Building 7.
(18325 K)
National Institute of Standards and Technology; National
Construction Safety Team
NIST NCSTAR 1A; 130 p. November 2008.
Keywords:
World Trade Center; building collapse; disasters;
building fires; building construction; fire
investigations; fire investigators; evacuation; fire
safety; structural collapse; high rise buildings;
structures; fire protection; combustibles; fire spread;
scenarios; structural analysis; failure; debris; impact;
damage; reconstruction; thermal effects; life safety;
emergencies; codes; standards; building design; human
performance; human factors engineering; fire endurance;
structural integrity; education; training; legislation;
structural design
Abstract:
This is the final report on the National Institute of
Standards and Technology (NIST) investigation of the
collapse of World Trade Center Building 7 (WTC 7),
conducted under the National Construction Safety Team
Act. This report describes how the fires that followed
the impact of debris from the collapse of WTC 1 (the
north tower) led to the collapse ofWTC 7; an evaluation
of the building evacuation and emergency response
procedures; what procedures and practices were used in
the design, construction, operation, and maintenance of
the building; and areas in current building and fire
codes, standards, and practices that warrant revision.
Extensive details are found in the companion reports,
NIST NCST AR 1-9 and NIST NCST AR 1-9A. Also in this
report is a summary 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; conducted
first-person interviews of building occupants and
emergency responders; analyzed the evacuation and
emergency response operations in and around WTC 7;
performed computer simulations of the behavior of WTC 7
on September 11, 2001; and combined the knowledge gained
into a probable collapse sequence. The report concludes
with a list of 13 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 emergency response, improved procedures and
practices, and education and training. One ofthese is
new; the other 12 are reiterated from the investigation
into the collapse of the WTC towers. Each of the 13 is
relevant to WTC 7.
