Institute Suggests Expansion Of Structural Endurance Concept
The National Institute of Standards and Technology, which released on Aug. 21 a draft of its final report on the collapse of Seven World Trade Center on September 11, 2001, is recommending that procedures and practices used to ensure fire endurance of structures be enhanced to prevent global collapse in the event of "infrequent" fires that occur when life safety systems fail or fires are not fought.
The fire at Seven WTC was triggered by debris from the collapse of One WTC. The 47-story building collapsed after burning for seven hours, unattended by firefighters. The primary cause was thermal expansion of the steel girders due to heat of the fires, says the report.