The
Commerce Department’s
National Institute of Standards and Technology (NIST) today
issued its second major progress report on the agency’s
federal building and fire safety investigation into the
World Trade Center (WTC) disaster of Sept. 11, 2001. At
a press
briefing in New York City, lead investigator Shyam Sunder
said that the NIST investigation team identified a series
of issues about test methods, standards, codes and emergency
operations currently used for buildings that merit further
analysis as the investigation moves toward completion.
The
NIST investigation’s goal is to recommend improvements
in the way people design, construct, maintain and use buildings,
especially high-rises. Sunder
explained that the findings released today may be revised
and additional
findings will be included in the team’s
final report, scheduled for release as a draft document in
December 2004. He also stated that NIST is not making any
recommendations at this time. All recommendations will be
made in the final report.
Key findings in the second interim report are summarized in the attached fact
sheet. The report includes:
- A
comprehensive summary of interim findings and accomplishments
for each
of the independent investigation
objectives.
- A
working hypothesis for the collapse of WTC 1 and WTC
2 (the towers)
that identifies the chronological
sequence of major collapse events and allows for different
possible load redistribution paths and damage scenarios
currently under analysis. The hypothesis will be refined
on the basis
of these analyses to determine the most probable collapse
sequence for each building.
- A
working hypothesis for the collapse of the 47-story
WTC 7 based
on an initiating event, a vertical progression
at the east side of the building, a subsequent horizontal
progression from the east to the west side of the building,
and global collapse.
- Key
visual observations on the building, fire and smoke
conditions in all three WTC buildings (the WTC towers
and WTC 7) from analysis of a large collection of photographic
and videographic images.
- A
summary of major progress in building comprehensive
models for
analyzing the most probable collapse sequence,
from aircraft impact to collapse initiation, and simplified
analytical models with results to supplement those from
detailed models.
- Results
from experimental work to (1) analyze the recovered
WTC structural steel, (2) support the fire dynamics
and thermal modeling, and (3) conduct fire endurance
testing of typical floor systems of the WTC towers based
on the current
standard (known as ASTM E 119).
- Reports
on the inventory and identification of the steels recovered
from the WTC buildings, and on the contemporaneous
(1960s era) structural steel and welding specifications
used to construct the WTC towers.
- First-person
interviews of nearly 1,200 WTC occupants, first responders
and families of victims to collect data
on occupant behavior, evacuation and emergency response
with some early results from analysis of that data.
- A
review of the New York City 9-1-1 tapes and logs and
the transcripts
of about 500 interviews with Fire Department
of New York (FDNY) employees involved in WTC emergency
response activities (the analysis of this material is
still in progress).
- Preliminary
analysis of emergency responder communication tapes
recorded by the Port Authority, including the high-rise
radio repeater, and by the New York Police Department
(NYPD),
including internal department operations.
- Analysis
of building and fire codes and practices, including:
a review of available documents related to the
design, construction, operation, maintenance and modifications
to the three WTC buildings; and a comparison of selected
building regulatory and code requirements.
- Analysis
of the design, capabilities and performance of the
installed active fire protection systems for all three
WTC buildings (i.e., fire alarm, sprinkler, and smoke
management
systems) with documentation of the fire history of the
WTC towers.
- Progress
on both the research and development and the dissemination
and technical assistance programs related
to the WTC investigation.
- Seventeen
appendices with detailed interim reports on specific
technical tasks within the eight investigation
projects where significant progress has been made.
The complete
report, including appendices, is available
on the comprehensive NIST WTC investigation Web site, http://wtc.nist.gov.
As a
non-regulatory agency of the U.S. Department of Commerce’s
Technology Administration, NIST develops and promotes measurement,
standards and technology to enhance productivity, facilitate
trade
and improve the quality of life.
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