Canadian Underwriter

NIST stresses need to secure tall buildings through design

June 23, 2005   by Canadian Underwriter

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The National Institute of Standards and Technology (NIST) has recommended the technical community implement changes in the design, materials, construction, maintenance and techniques i.e. changes to codes and standards to improve tall building safety and performance.
The report, based on a three-year investigation into the destruction of the World Trade Center, states the towers may not have collapsed if the spray-on fireproofing had not been dislodged by the impact of the aircraft.
As a result of the report’s findings, the NIST’s recommendations are heavily focused on the effects of fire in relationship to other structural loads. NIST’s suggestions resonate the findings of the American Society of Civil Engineers (ASCE) and Federal Emergency Management Agency (FEMA)’s assessment report released May 2002.
“The report provides the comprehensive analysis needed to progress from determining the cause of the collapse to finding ways to improve building performance,” Gene Corley, PhD., P.E., team leader for the ASCE/FEMA study team, says. “We’ve certainly learned a lot from studying how the towers and the surrounding buildings performed when subjected to extreme forces. But we also have decades of experience with the performance of other structures subjected to intense fire.”
Structural Engineering Institute of ASCE representatives indicate that further study into the specific kinds of events and environments that compromise fireproofing materials are required and they further called for the development of testing facilities capable of studying the effects of fire on long-span steel beams. ASCE assessments have indicated that common fireproofing methods used in both steel-frame and reinforced concrete construction are vulnerable to being ‘scoured’ by the force of the debris field following a significant impact.
The ASCE/FEMA report recommended improvements in fireproofing, sprinkler systems and egress design-in the design and construction of buildings deemed likely targets of terrorist attacks
NIST issued 30 specific recommendations covering eight areas: increased structural integrity; enhanced fire resistance of structure; new methods for fire-resistant design of structures; active fire protection; improved building evacuation; improved emergency response; improved procedures and practices; and, education and training.
Some examples of specific recommendations include the use of standards and codes to prevent progressive collapse and more reliable means of predicting failure in buildings subjected to multiple hazards as well as improvements to the 100-year-old standard for fire-resistance testing of building components, assemblies and systems.
The NIST calls on private organizations that develop safety standards as well as state and local agencies that adopt and enforce them, to pursue the recommendations.

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