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Contracts
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THERMAL-STRUCTURAL
RESPONSE OF THE WORLD TRADE CENTER TOWERS WITH AND WITHOUT IMPACT DAMAGE
TO DETERMINE PROBABLE COLLAPSE INITIATION SEQUENCES
Under solicitation
number SB1341-03-R-0044, an indefinite deliverable, indefinite quantity
(IDIQ) purchase order has been awarded to Simpson Gumpertz & Heger
Inc. (SGH) of Waltham, Massachusetts, to determine the response of structural
components and systems to the fire environment in the World Trade Center
towers and to identify probable structural collapse mechanisms.
SGH is an engineering
firm that specializes in design, investigation and retrofit of buildings
and structures of all types. SGH has a highly skilled technical staff
with expertise in building structures, materials, and investigation and
specialized research and is well qualified to conduct the structural fire
response and collapse analysis of the World Trade Center towers.
SGH strengths include:
advanced finite element analysis capabilities; expertise in building technology,
materials analysis and testing and engineering mechanics; sophisticated
investigative capabilities utilizing state of the art NDE and monitoring
technologies. SGH is partnering with Computer Aided Engineering Associates
(CAEA), an engineering consulting company specializing in advanced engineering
analysis services. CAEA specializes in thermal-stress analysis and has
extensive experience in applied mechanics, dynamics, contact mechanics
and finite element code development.
Together, SGH and
CAEA bring many years of experience in nonlinear finite analysis, high-rise
building design, material studies for thermal effects and failure investigations.
The specific tasks
that SGH will perform include:
- Develop and validate
thermal-structural models of floor and column component and subsystem
models, including passive fire protection.
- Determine the
transient thermal-structural response of the component and subsystem
models to standard test fire conditions (ASTM E119 and E1529).
- Estimate the
thermal environment necessary to damage or fail critical members or
connections.
- Develop and validate
a global thermal-structural model, including passive fire protection,
assuming no impact damage. Conduct analysis for ASTM E119 and E1529
standard fires and for estimated heat flux densities and temperatures
in undamaged compartments.
- Develop and validate
global thermal-structural models with aircraft impact damage by modifying
the undamaged model for each tower. Conduct thermal and structural analysis
of possible fire growth and spread sequences in each tower.
- Conduct parametric
studies to determine the effect of uncertainty in influential parameters
on predicted outcomes and on the most probable collapse sequence.
The studies are based
upon the approach described in the paper “Assessing the Most Probable
Structural Collapse Sequence: Integrating Impact Damage, Fire Dynamics,
Thermal-Structural Response, & Collapse Initiation.”
- Identify candidate
collapse initiation hypotheses for each tower from analyses.
The key personnel
at SGH and CAEA include: Project Manager, Mehdi Zarghamee; Structural
Performance Review Committee, Glen Bell, Ronald Hamburger and Pedro Sifre;
Computation/Modeling Review Committee, Said Bolourch, Atis Liepins and
Peter Barrett; and Computation Manager, Frank Kan.
- Mehdi S. Zarghamee,
a Principal and Head of the Engineering Mechanics and Infrastructure
Division at SGH, has 30 years of engineering experience in analysis
and design of precision structures. He has been responsible for analysis,
design, and failure investigation of complex structural and mechanical
systems. Dr. Zarghamee earned his Ph. D. in Structural Engineering from
the University of Illinois and his S.M. in Mathematics from the Massachusetts
Institute of Technology.
- Glen Bell, Principal
and Chief Executive Officer, has been with SGH for 28 years. Mr. Bell
specializes in structural failure investigations and has extensive experience
in earthquake engineering, structural design and rehabilitation. He
received his B.S. degree in Civil Engineering from Tufts University
and his M.S. in Structural Engineering and Structural Mechanics from
the University of California at Berkeley.
- Ronald Hamburger,
a Principal at SGH, has 28 years of experience in civil and structural
engineering, damage and forensic investigations, engineering research,
building code and standards development and project management. He was
a member of the Building Performance Assessment Team that investigated
the collapse of the World Trade Center Buildings in New York. Mr. Hamburger
received his M.B.A. from Golden Gate University and his B.S. and M.S.
from the Polytechnic Institute of New York.
- Pedro Sifre, Senior
Project Manager, has 16 years of experience in high-rise building design
and optimization of lateral load resisting systems. He received his
B.S. in Civil Engineering and his M.S. in Aeronautics and Astronautics
from the Massachusetts Institute of Technology and his M.S. in Structural
Engineering from the University of California at Berkeley.
- Atis Liepins,
a Senior Associate has been with SGH for 25 years. He is an expert in
the performance of finite element analysis, structural design, and failure
analysis. Mr. Liepins received his S.B., S.M., and C.E. in Civil Engineering
from the Massachusetts Institute of Technology.
- Said Bolourchi,
Staff Consultant, has 24 years of experience. His expertise is in risk
assessment and failure analysis and evaluations including nonlinear
dynamic analysis and response spectrum analysis of structures. Dr. Bolourchi
received his B.S. in Mechanical Engineering from Queen Mary College,
London, and his M.S. in Mechanical Engineering and Ph.D. in Applied
Mechanics from the Massachusetts Institute of Technology.
- Peter Barrett,
Consultant, has over 20 years of experience in thermal-structural analysis
applications using the finite element method and has been with CAEA
since 1993. He has conducted numerous geometric and material nonlinear
static and dynamic analyses to evaluate the strength, stability, and
fatigue life of structures.
- Frank Kan, a Senior
Project Manager, has been with SGH for 16 years. He has been involved
in structural and seismic analysis, design, and investigation of buildings,
bridges and special structures. Mr. Kan received his B.Eng. in Civil
Engineering and Engineering Mechanics from McMaster University, Ontario,
and his M.S. in Civil Engineering from the Massachusetts Institute of
Technology. As Computation Manager, Mr. Kan will be responsible for
all computational aspects of the project as well as coordination between
the SGH Computation Team and the CAEA Consultant Team.
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