Final Reports of the Federal Building and Fire
Investigation of the World Trade Center Disaster
NIST NCSTAR 1-3: Mechanical and Metallurgical Analysis of
Structural Steel
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: Determine mechanical properties of WTC structural steel,
Determine the quality of the steel and if design requirements were met, and
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 documents.
The reports provided here are presented in .pdf format. To read these files, you can download
the
latest version of Adobe Acrobat Reader free. If you have difficulty
reading pdf files, you may need to update
your version of Acrobat reader to the latest version. These 7 pdf
files for Project 1-3 may also be downloaded as a group within a
WINZIP (.zip) file. (Note: this
file is very large - 102 MB)
