Mechanical and Metallurgical Analysis of Structural Steel. Federal Building and Fire Safety Investigation of the World Trade Center Disaster.
Mechanical and Metallurgical Analysis of Structural
Steel. Federal Building and Fire Safety Investigation
of the World Trade Center Disaster.
Gayle, F. W.; Fields, R. J.; Luecke, W. E.; Banovic, S.
W.; Foecke, T.; McCowan, C. N.; Siewert, T. A.;
McColskey, J. K.
NIST NCSTAR 1-3; 184 p. September 2005.
World Trade Center; high rise buildings; building
collapse; disasters; fire safety; fire investigations;
terrorists; terrorism; steel structures; mechanical
properties; failure analysis; specifications; steels;
construction; damage; physical properties; structural
This report is an overview of the results of the
mechanical and metallurgical analysis of structural
steel from the World Trade Center (WTC), part of the
National institute of Standards and Technology
Investigation of the WTC disaster of September 11, 2001.
The goal of the study was threefold: (1) Determine
mechanical propetties of WTC stnctural steel, (2)
Determine the quality of the steel and if design
requirements were met, and (3) Analyze the recovered
steel to provide insight into failure mechanisms to
guide and/or validate models of building performance.
Structural steel recovered from the WTC site was
analyzed for composition, microstructure, and mechanical
properties, including room temperature properties (for
modeling baseline building performance), high
temperature properties (for modeling structural response
of the building to fire), and behavior at high strain
rates (for modeling airplane impact). Failure analysis
of the recovered steel, complemented by pre-collapse
photographs of the damaged building, was used to
establish failure modes and temperature excursions
experienced by the steel. In addition, documents from
the construction era covering issues ranging from steel
specifications to engineering design drawings were used
to help interpret the results and supplement models of
mechanical properties used in the models of building
performance. The analysis focused on the WTC 1 and WTC
2. Although no steel was recovered from WTC 7, a
47-story building that also collapsed on September 11,
properties for steel used in its construction were
estimated based on literature and contemporaneous