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First Comprehensive Set of Model Code Changes Adopted Based on Recommendations from Commerce's NIST World Trade Center Investigation
For Immediate Release: June 20, 2007
Michael E. Newman
GAITHERSBURG, Md.-Safer buildings-especially tall structures-that are more resistant to fire and more easily evacuated in emergencies are the goal of the first comprehensive set of building code changes recently approved by the International Code Council (ICC) based on recommendations from the Commerce Department's National Institute of Standards and Technology (NIST). The recommendations were based on the findings of NIST's three-year investigation of the collapses of New York City's World Trade Center (WTC) towers on Sept. 11, 2001. The changes will be incorporated into the 2007 supplement to the ICC's International Building Code (IBC), a model code used as the basis for building regulations promulgated and enforced by U.S. state and local jurisdictions. Those jurisdictions have the option of incorporating some or all of the code's provisions but generally adopt most provisions.
"We fully endorse these code changes and are gratified that NIST's WTC recommendations have stimulated fundamental and substantial changes in U.S. building codes and standards that represent a significant improvement in public safety over current practice," says Shyam Sunder, lead WTC investigator for NIST. "NIST is committed to continuing our work to support industry and the nation's building and fire safety officials so that the remaining recommendations are also fully considered."
All but one of the proposed changes (one change was approved earlier) to the IBC based on the NIST WTC investigation recommendations were submitted in March 2006 by the ICC's Ad Hoc Committee on Terrorism Resistant Buildings, its Code Technology Committee and the U.S. General Services Administration. The proposals were developed and refined on the basis of feedback provided by building code experts convened by the National Institute of Building Sciences (NIBS) with support from NIST.
The proposals addressed areas such as increased resistance to building collapse from fire and other incidents, use of sprayed fire-resistive materials (commonly known as "fireproofing"), performance and redundancy of fire protection systems (i.e., automatic sprinklers), fuel oil storage/piping, elevators for use by first responders and evacuating occupants, the number and location of stairwells, and exit path markings.
The model code changes consistent with the NIST WTC investigation recommendations that are now required by the IBC-including those approved at the ICC final action hearings in Rochester, N.Y., during May 21-26, 2007-are:
"In the first case, a broad industry coalition has made excellent progress toward developing a proposal to be submitted by the August 2007 deadline for the next code revision cycle," according to Sunder.
If adopted, the new model code provision would recommend that structures be designed to mitigate disproportionate progressive collapse and ensure, for the first time, minimum structural integrity and robustness requirements for structures as complete systems.
The second proposed code change would require the use of a nationally accepted standard for conducting wind tunnel tests routinely used for determining wind loads in the design of tall buildings. During its investigation of the collapses of the WTC towers, NIST found that wind load estimates from three separate wind tunnel tests on WTC models differed greatly. This code change proposal is awaiting final adoption of a standard for conducting wind tunnel tests by the American Society of Civil Engineers (ASCE). A nationally accepted standard for estimating wind loads and their effects on tall buildings based on wind tunnel testing and directional wind speed data-a NIST recommendation above and beyond the standard for conducting such tests-remains to be developed.
Four model code change proposals that were not accepted into the IBC this time are being revised using feedback from ICC members at the May final action hearing. The revised proposals are expected to be resubmitted this August for adoption in the next code revision cycle for the IBC in 2009. These proposals require:
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