The Pentagon Building Performance Report

Abstract

• Sponsored by the Structural Engineering Institute of ASCE

  This report presents the significant findings of a building performance team that investigated the structural damage sustained by the Pentagon after an airplane was crashed into it on September 11, 2001. The team, which was constituted on the day of the crash, reviewed available information on the structure, crash loading, and eyewitness accounts; the team also drew on focused assessments by others. After performing impact, static, and thermal analyses, the team made recommendations for future design and construction and suggestions on areas where research and development is needed.

  With more than 150 color photographs, diagrams, and tables, this report provides a thorough assessment of the structural system that prevented extensive collapse of the building. From the redundant and alternative load paths of the unique beam and girder framing system, to the ability of the structure to absorb excess energy, the Pentagon withstood both structural and thermal trauma better than would have been expected. Complete with a chronological description of the events leading to impact, the crash and its subsequent effect on the structural system, this report reveals exactly how and why the Pentagon structure performed so well on the morning of the September 11, 2001 attacks.

  This report will be of interest to structural and forensic engineers, as well as historians and general readers seeking first-hand, technical knowledge of the Pentagon's resistance to progressive collapse.