Structural Fire Engineering Applied to World Trade Center 7: Analysis of Failure and Design Recommendations

Abstract

The original World Trade Center 7 (WTC 7) collapsed on September 11, 2001 due to fire caused by falling debris from World Trade Center 1. On Floor 13, beams in the North-East quadrant of the building expanded against a critical girder and caused connection failure between the girder and an interior column. This triggered a sequence of events that led to the complete collapse of WTC 7. Although the building was designed to code, it was not able to withstand fire. The objective of this study is to analyze the initiating event of collapse in WTC 7 using the principles of structural fire engineering (SFE). SFE prioritizes safety and project-specific designs and promotes mindfulness when designing for fire. A comprehensive report on the WTC 7 collapse produced by National Institute of Standards and Technology (NIST) serves as the primary source of information. Parametric analysis is conducted in order to study the effects of frame properties on resulting forces. Of particular interest are beam layout and boundary conditions. Based on the results of the parametric analysis, recommendations for more effective fire design are proposed.