Remarks
by Dr. Shyam Sunder, Lead Investigator Thank you, Dr.
Bement. Good morning to you all. I'd like to share with you specific
details on the scope of the investigation, some of the advanced
tools we expect to use, the steel we have recovered from the site,
the broader data collection process, our plans to deal with human
subjects, and the team we have assembled to carry out the investigation. The NIST building
and fire safety investigation will focus exclusively on three buildings:
the WTC Towersor WTC 1 and 2, and WTC 7the 47-story
building that collapsed later in the day on September 11, 2001.
The lessons
to be derived from our investigation, that were enumerated earlier
by Dr. Bement, will benefit a broad range of new and existing buildings,
not just the three specific buildings that are studied. As part of the investigation, we plan to conduct eight specific projects that will address the overall objectives.
We intend to
use advanced scientific methods and tools extensively in the investigation.
As an example, consider the preliminary simulation of the fireball
that was generated when the second aircraft crashed into the South
Tower, WTC 2. This simulation used NIST's Fire Dynamics Simulator,
or FDS. It will help us estimate the amount of jet fuel that was
consumed in the fire balls. Other examples, included in the B-roll
tape provided to you, show how FDS can be used to evaluate the source
strength of the fire by modeling the smoke plume and to analyze
the fire and smoke movement within the buildings. In the investigation,
we plan to develop far more accurate representations of the WTC
buildings, their contents and thermal properties, and air supply
within them to reconstruct the time-evolving temperature and smoke
environment using this tool. The results of these reconstructions
will be used to evaluate the structural response of the buildings
in fire, and the behavior and fate of occupants and responders. NIST now has
in its possession in excess of 100 pieces of steel from the WTC
site that were identified by the Structural Engineers Association
of New York and other BPAT members, including NIST. These pieces,
several of which you see around here, include perimeter columns,
wide-flanged beams, and trusses. We plan to determine
the metallurgical and mechanical properties of the steel, weldments,
and connections, and to document the observed failure mechanisms
and damage. This work will be very useful in estimating the temperature
conditions in the buildings before collapse, and in analyzing both
the structural response of the buildings to fire and the damage
induced by the aircraft impact on the structural, egress, and fire
protection systems. I would like
to draw your attention to the three pieces of steel on my left.
The large upstanding piece is a prefabricated column element that
was directly impacted by the first aircraft that crashed into the
North Tower, WTC 1. The identification markings are visible clearly.
As the charts here indicate, this piece of steel is one of many,
now at NIST, tentatively identified to be from the near vicinity
of the impacted region of this tower. We expect to test this steel
at extremely high rates of loadingtypical of those that would
be encountered in an aircraft impactusing advanced technology
now under development at NIST. The second piece
is a damaged and twisted open-web steel truss. This is a rare truss
specimen that survived the collapse and was located by engineers
at the salvage yards. The WTC towers made extensive use of these
types of trusses to support the floor system by spanning the 35-
to 60-feet distance between the exterior and interior columns. There
is great interest in understanding how these types of trusses perform
in fires, the ability of spray-applied fireproofing to stay in place
on these trusses under shock, vibration, or impact, and how they
are connected to the columns. The third piece
is a highly deformed and wrinkled column from one of the upper floors
that we hypothesize could have been subjected to intense heat. A
metallurgical analysis, that carefully studies changes in the microstructure
of the steel, will allow us to estimate the temperatures reached
in this specimen. More broadly,
we intend to base all of our review, analysis, modeling, and testing
work for the investigation on a solid foundation of technical evidence.
This will require unfettered and timely access to critical data
such as building documents, video and photographic records, oral
histories, and emergency response records in addition to the steel
that has been recovered. The Port Authority
of New York and New Jersey and Silverstein Properties have offered
to provide NIST with access to all such information in their possession
or in the possession of their contractors and consultants. New York
City authorities have also offered to fully cooperate with NIST
in its investigation. We'd like to
put out a special call today for photographic and video images that
could help us better document the initial damage and the subsequent
fire growth and spread in the WTC Towers and WTC 7. We are especially
interested in WTC 7 and views of the South and West faces of the
towers. Those who are aware of or in actual possession of such materials
are encouraged to contact us. Our study of
occupant behavior, evacuation, and emergency response will require
a systematic collection of new data from survivors, families of
victims, witnesses, and others with operational responsibility on
September 11, 2001. The NIST Director
has directed us to carry out the investigation to the highest technical
and professional standards, by treating all those who experienced
this disaster first hand with kindness and sensitivity, and in accordance
with all legal and administrative requirements. We will use
established procedures to carefully review all survey and interview
questions, data collection methods, and safeguards for maintaining
privacy and confidentiality before proceeding with these critical
data collection efforts. Finally, NIST
has assembled a seasoned world-class team to carry out the investigation.
This team has the needed technical expertise as well as experience
from significant prior investigations. Over two dozen NIST experts
will be involved over the course of the investigation. In addition,
we expect to significantly augment our in-house staff with external
world-class experts in our project teams and as contractors. This concludes
my prepared remarks. Thank you. |
For additional information: WTC Contacts | Building and Fire Research Laboratory | NIST |
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Last updated: 8/20/2002