THE 2000 NEHRP EDITION


In September 1997, NIBS entered into a contract with FEMA for initiation of the 48-month BSSC effort to update the 1997 NEHRP Recommended Provisions for Seismic Regulations for New Buildings and Other Structures. During this project, the 1997 Provisions will be revised for re-issuance in 2000 and code changes based on the 2000 Provisions will be prepared for submittal to the IBC.

In lieu of the Seismic Design Procedure Group (SDPG) used in the 1997 update, the BSSC has re-established Technical Subcommittee 1, Seismic Design Mapping, used in earlier updates of the Provisions. This subcommittee is composed of an eaqual number of representatives from the earth science community, including representatives from the USGS, and the engineering community.

An additional 11 subcommittees were formed to address seismic design and analysis, foundations and geotechnical considerations, cast-in-place and precast concrete structures, masonry structures, steel structures, wood structures, mechanical-electrical systems and building equipment and architectural elements, quality assurance, composite steel and concrete structures, base isolation and energy dissipation, and nonbuilding structures. Two ad hoc task groups have been formed: one to develop appropriate anchorage requirements for concrete/masonry/wood elements and the other to develop a simplified procedure for use in the lower seismic risk areas. No technical subcommittee has been provided in this update cycle to serve specifically as the interface with codes and standards; rather, the Code Resource Support Committee and its Technical Group are expected to provide for the needed liaison between the PUC and the model code and standards organizations.

The BSSC, through the PUC and TS's, identified major technical issues addressed during the 2000 update of the NEHRP Recommended Provisions, assessing the basis for change to the 1997 Edition, resolved technical issues, and developed proposals for change. The results of recent relevant research and lessons learned from earthquakes occurring prior to or during the duration of the project will be given consideration at all stages of this process. Particular attention will be focused on those technical problems identified but unresolved during the preparation of the 1997 Edition. Attention also will be given to the improvement of criteria to allow for design based on desired building performance levels reflecting the approach taken in the NEHRP Guidelines for the Seismic Rehabilitation of Buildings (FEMA Publication 273). The PUC also will coordinate its efforts with those individuals working with the ICC to develop the IBC. Changes recommended by those individuals will be submitted to the PUC for consideration and changes developed by the PUC will be formatted for consideration in the IBC development process.

As part of the update process, the BSSC also has worked to develop a simplified design procedure in order to improve use of the Provisions in areas of low and moderate seismic hazard.

The first ballot encompassing 146 proposals for change to the 1997 Provisions was submitted to the BSSC member organizations on April 10, 2000; the ballot deadline was June 10. The proposals for change also were posted for comment on the BSSC website – www.bssconline.org.

Of the 64 member organizations sent ballot packages, 42 responded. Of the 146 proposals, 69 passed with no "no" votes but some "yes with reservations" votes, 71 passed with "no" and "yes with reservations" votes, and 6 did not pass (i.e., received less than 67 percent "yes" and "yes with reservations" votes). The comments submitted with "no" and "yes with reservations" votes were compiled and distributed to the PUC Technical Subcommittee chairs. The PUC then met in Denver on July 13-14, 2000, to receive the TSs responses to ballot comments and formulate recommendations concerning items that need to be submitted to the member organizations for a second ballot.

In August 2000, the PUC Chair, William Holmes, briefed the BSSC Board of Direction on the results of the first ballot and recommended that 17 items be submitted to the membership for a second ballot. Ten of the proposals were revisions of previous proposals, three were new proposals, and four were proposals developed by the PUC to clarify concerns arising from the first ballot. The official second ballot package was mailed to BSSC member organizations on September 5, 2000 with completed ballots due October 5, 2000. Of the 66 BSSC member organizations, 42 responded and all proposals passed. There were, however, several "yes with reservations" and "no" votes, and the PUC met on October 30-31, 2000, to resolve the comments submitted with these votes and to formulate recommendations concerning a third ballot.

On November 1, 2000, the PUC chair presented the second ballot results to the BSSC Board and recommended that several items be submitted to the membership for a third ballot. The primary purpose of the third ballot was to permit integration into the 2000 Provisions of new steel requirements resulting from the FEMA-funded SAC effort mounted to study damage during the Northridge earthquake and of the most current version of the American Institute of Steel Constructions standard which was expected to include many of the SAC requirements. The third ballot, which included five proposals, was sent to the membership on December 28, 2000, with ballot due by February 7, 2001. Of the 65 member organizations, 44 submitted ballots (67 percent). All five proposals passed and the results were reviewed and comments resolved by the PUC Executive Committee at a meeting on March 5, 2001.

The PUC chair briefed the BSSC Board on the third ballot results on March 6, 2000, and the Board unanimously approved the 2000 Provisions for transmittal to FEMA following a final editorial review by the PUC of the Provisions document and its accompanying Commentary volume. Reports identifying the major differences between the 1997 and the 2000 Editions of the Provisions and describing unresolved issues and major technical topics in need of further study are were prepared. The final version of the 2000 Provisions was officially transmitted to FEMA in June 2002 and both the 2002 Provisions and Commentary volumes are available in pdf format for download on the BSSC website (www.bssconline.org).

Code-language versions of changes for the 2000 Provisions for submittal as proposed code changes for the 2003 Edition of the IBC and IRC have been prepared and submitted to the International Code Council (ICC) for consideration at April 2002 hearings. In addition, the Provisions underwent a detailed edit to eliminate undue repetition and inconsistencies late in the 2000 update cycle; this document is intended to serve as the base document for the 2003 update cycle following review by the 2003 PUC and balloting by the BSSC member organizations.

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