Probable Cause Sequences for WTC Collapses Finalized

Apr 12, 2005

At a press briefing in New York City on April 5, the National Institute of Standards and Technology (NIST) presented its analysis of how the World Trade Center (WTC) towers collapsed after two aircraft were flown into the buildings by terrorists on Sept. 11, 2001. The study is the most detailed examination of a building failure ever conducted.

“Like most building collapses, these events were the result of a combination of factors,” said Shyam Sunder, lead investigator for the agency’s building and fire safety investigation into the WTC disaster. “While the buildings were able to withstand the initial impact of the aircraft, the resulting fires that spread through the towers weakened support columns and floors that had fireproofing dislodged by the impacts. This eventually led to collapse as the perimeter columns were pulled inward by the sagging floors and buckled.”

The probable collapse sequences update and finalize hypotheses released by NIST last October. The sequences are supported by extensive computer modeling and the evidence held by NIST, including photographs and videos, recovered steel, eyewitness accounts and emergency communication records. Additionally, this information was used to document a variety of factors affecting the performance of the buildings, the efforts of emergency responders and the ability of occupants to escape prior to the collapses. In turn, NIST has identified a number of future practices and technologies that potentially could have enhanced building performance and life safety capabilities on 9-11 had they been available for implementation.

NIST also released drafts of 15 reports from three projects of the investigation: analysis of building and fire codes and practices; occupant behavior, egress and emergency communications; and fire service technologies and guidelines.

Recommendations for improvements to building and fire codes, standards and practices derived from these and the other five projects in the investigation will be released for public comment in June, along with the draft of the final investigation report and drafts of 27 reports from the remaining five projects.

Source: NIST

Explore further: The stapes of a neanderthal child points to the anatomical differences with our species

add to favorites email to friend print save as pdf

Related Stories

Recommended for you

Destroyed Mosul artefacts to be rebuilt in 3D

Mar 27, 2015

It didn't take long for the scientific community to react. Two weeks after the sacking of the 300 year-old Mosul Museum by a group of ISIS extremists went viral on Youtube, researchers from the ITN-DCH, IAPP ...

Boys plagiarise more than girls at school

Mar 27, 2015

Research by the University of the Balearic Islands has analysed the phenomenon of academic plagiarism among secondary school students. The study, published in the journal Comunicar, confirms that this practi ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.