Simulating the Fires in the World Trade Center.
Simulating the Fires in the World Trade Center.
(1327 K)
McGrattan, K. B.; Bouldin, C.
Volume 2;
Interflam 2004. (Interflam '04). International
Interflam Conference, 10th Proceedings. Volume 2. July
5-7, 2004. Organised by Interscience Communications
Ltd. in association with National Institute of Standards
and Technology, Building Research Establishment;
National Fire Protection Association; Society of Fire
Protection Engineers; and Swedish National Testing and
Research Institute, Edinburgh, Scotland, Interscience
Communications Ltd., London, England, 999-1008 pp, 2004.
Keywords:
fire science; fire safety; World Trade Center;
validation; experiments; simulation; temperature; fire
investigations; building collapse; fire spread
Abstract:
In the months following the attacks on the World Trade
Center and the Pentagon, there was an active debate in
the fire protection engineering community about the
fires that erupted following the impact of the aircraft
on the buildings. Because fires of this magnitude in
these types of buildings are rare, there is a wide
spectrum of opinion about the fire temperatures and
their effect on the structural steel. Much of the fire
literature consists of empirical correlations derived
from experiments ranging from bench scale to room scale.
Extrapolating these well-known correlations to the WTC
requires a re-examination of the underlying assumptions.
Many of these correlations are appropriate for a narrow
range of fire sizes and building geometries, and can not
be directly applied to the WTC fire scenarios. As a
result, computer fire models that have been developed
over the past decade are being applied to the analysis.
The National Institute of Standards and Technology
(NIST), an agency of the United States Department of
Commerce, is conducting an investigation of the collapse
of WTC 1, 2 and 7. WTC 1 and 2 were the 110 floor
towers, and WTC 7 was the 47 floor office building north
of WTC 1 that collapsed at 5:20 in the afternoon of
September 11, 2001. As part of the investigation, NIST
has conducted simulations of the fires in each building
using a computational fluid dynamics (CFD) model known
as the Fire Dynamics Simulator (FDS). This paper will
describe the experiments conducted at NIST to calibrate
and validate the FDS model for use in the WTC project,
and it will describe the techniques developed to
simulate the very extensive fires that spread over 6 to
12 floors in the different buildings. This paper does
not present any of the subsequent work to analyze the
thermal response of the steel structure, nor does it
present any collapse hypotheses. These efforts will be
described elsewhere.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899