World Trade Center Collapse Investigation

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After the infamous terrorist attack on the World Trade Center on September 11, 2001, CTLGroup, under the direction of Dr. Gene Corley, was asked to investigate the collapse of the Twin Towers, resulting from the impact of the two airplanes on the buildings. Dr. Corley was the team leader of the investigation and managed engineers from 17 other firms. Their goal was to determine why the buildings completely collapsed after being struck by the planes. The contention was that buildings of that size should have been able to withstand the collisions. The Structural Engineers Institute and FEMA gave Corley’s team a deadline of six months in which to complete the investigation and deliver the report.

Corley’s investigative team went to Ground Zero to collect information. The team studied the architectural and engineering design plans for the buildings, as well as operational and design details. They reviewed photos, videos, and data gathered from New York City’s recovery and rescue efforts.

On May 1, 2002, Dr. Corley and his team testified before Congress, submitting their written report, as well as an oral summary of the report. Their findings indicated that the lack of fire-proofing of the building led to much of the severity of the destruction. The National Institute of Standards and Technology (NIST) conducted follow-up investigations, finding that Corley’s report was correct. Data is still being collected to this day, and the report continues to stand up under intense scrutiny.

The recommendations on structural fireproofing that arose from Corley’s report are gradually being implanted in building construction throughout the industry.