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Overview of the Structural Design of World Trade Center 1, 2, and 7



Therese P. McAllister, Fahim Sadek, John L. Gross, Jason D. Averill, Richard G. Gann


This paper summarizes the primary structural systems which comprised World Trade Center 1, World Trade Center 2, and World Trade Center 7. The buildings were destroyed in the terrorist attacks of September 11, 2001. This paper describes the four major structural subsystems in the towers: the exterior wall, the core, the floor system, and the hat truss. Additionally, the major structural systems within WTC 7 are described: foundation, lateral load resisting system, floor system, and columns.
Fire Technology


World Trade Center, Investigations, Building Collapse, Structural Design


McAllister, T. , Sadek, F. , Gross, J. , Averill, J. and Gann, R. (2012), Overview of the Structural Design of World Trade Center 1, 2, and 7, Fire Technology, [online], (Accessed April 19, 2024)
Created September 1, 2012, Updated November 10, 2018