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Physical Properties of Structural Steels. Federal Building and Fire Safety Investigation of the World Trade Center Disaster (NIST NCSTAR 1-3E) ***DRAFT for Public Comments***



Stephen W. Banovic, Christopher N. McCowan, William E. Luecke


This report describes the physical properties of the structural steel recovered from the World Trade Center (WTC) towers. Analytical techniques were used to determine and evaluate the chemistry, microstructure, and thermal properties of the steels. While not a physical property, hardness of the steels was also measured and discussed in relation to strengthening mechanisms of the material. The primary focus was on structural components with known as-built locations from WTC 1 and WTC 2. Evaluation of samples without known as-built locations was conducted in order to fully characterize all of the structural elements. The physical property information was found useful in helping to identify specific grades and producers of steel used for the various components. In addition, the thermal properties were developed for the use in the models of the building response to fire. Although no recovered structural elements were from WTC 7, physical property data of steels from this building were estimated based upon values found in the literature. In addition to the structural steel, chemistry information was measured for a piece of the aluminum facade used on the WTC towers and the sprayed fire-resistive material applied to the structural elements of WTC 2 and WTC 2.
National Construction Safety Team Act Reports (NIST NCSTAR) - 1-3
Report Number


World Trade Center, high rise buildings, building collapse, disasters, fire safety, fire investigations, terrorists, terrorism, steel structures, physical properties, chemical analysis, hardness, microstructure, thermal properties
Created September 1, 2005, Updated February 19, 2017