http://www.nist.gov/el/disasterstudies/wtc/wtc_contracts.cfm 1

Awarded Contracts for External Experts to Support the 

NIST World Trade Center (WTC) Disaster Investigation

Contract No. Awarded to Date Awarded

SB1341-03-W-0716 (Area 4) Teng & Associates, Inc. 7/3/2003

OUTSIDE EXPERTS FOR BASELINE STRUCTURAL PERFORMANCE, IMPACT ANALYSIS, 

STRUCTURAL RESPONSE TO FIRE, COLLAPSE, ETC.

Under solicitation number SB1341-03-Q-0322, firm fixed-price purchase orders have been awarded to 

experts in five technical areas for their experience and judgment at the most senior professional level to 

provide expert technical assistance as follows:

Area 4: Structural System Failure and Collapse Sequences

A purchase order for Area 4 has been awarded to Teng & Associates in Chicago, Illinois to provide 

technical expertise and assistance for analysis of structural systems, failure, and collapse sequences of 

WTC 1, 2, and 7. Structural system analysis includes the design, analysis, and behavior of high-rise steel 

buildings, lateral (wind) and gravity systems, connection design, structural redundancy, and load 

redistribution. Structural collapse analysis includes failure behavior and characterization of structural 

systems under extreme loads, finite element modeling of member and system failure, local and global 

instability, large deflections, yielding, fracture, and creep. The specific tasks the experts will perform 

include:

Provide expert technical assistance in finite element and analytical modeling of member failure 

sequences leading to collapse initiation, appropriate constitutive models for members 

experiencing thermally-induced capacity reduction and/or increased loads from load 

redistribution, and failure criteria for members and system failure. 

Conduct in-depth, review and critique of the work done on the collapse analysis of the WTC 

towers. The review shall include: a) appropriateness of the models for their intended uses, 

including modeling assumptions, level of detail, model geometry and material properties, and 

verification and validation procedures; and b) appropriateness of the analyses and accuracy of 

results. 

The team from Teng & Associates consists of a Principal Structural Consultant and two licensed structural 

engineers (SE) with relevant backgrounds and appropriate knowledge in structural design and analysis of 

steel high-rise buildings and the behavior and characterization of structural system failure:

Dr. Shankar Nair, Senior Vice President of Teng & Associates, is the Principal Structural 

Consultant. Dr. Nair is a licensed structural engineer with a doctorate in civil engineering and over 

33 years of experience in the design and analysis of high-rise building structures. He has 

developed many of the structural designs of Chicago’s tall buildings of 30 to 70 stories. Dr. Nair 

has published numerous technical papers on tall building design, advanced structural analysis 

methods, and global structural stability theory and analysis. The quality of engineering in Dr. 

Nair’s work has been recognized by awards from the American Institute of Steel Construction, the 

American Consulting Engineers Council, and twelve awards from the Structural Engineers 

Association of Illinois, including six of the annual Most Innovative Structure awards. He served as 

the chairman of the Council on Tall Buildings and Urban Habitat from 1997 to 2001. 
2 http://www.nist.gov/el/disasterstudies/wtc/wtc_contracts.cfm

Mr. Miroslav Sulc is a licensed structural engineer with a master’s degree in architectural and 

structural engineering and over 30 years of experience in project management, structural design 

and analysis, and review of working and shop drawings. Mr. Sulc has a broad range of 

experience of building types and construction, with a specialization in wind analysis, shear walls, 

and foundation design. 

Dr. Todd Ude is a licensed structural engineer with a doctorate in civil engineering and 

experience in structural reliability, extreme loads and dynamic response analysis. His experience 

includes detailed nonlinear analyses of an existing steel bridge structure that consider yielding, 

fatigue, and fracture failure modes.