Book Description

Among the FEMA documents covering the topic of making existing buildings more resistant to the effects of earthquakes, this volume occupies a unique position: it is the only one that fulfills a historical need. When the decision was made to convert the performance-based Guidelines for the Seismic Rehabilitation of Buildings, FEMA 273, into a prestandard containing mandatory language (FEMA 356), there was considerable concern among design professionals that some of the major characteristics and salient features of the original document (or indeed its very fabric) would be adversely affected in the conversion process. This Global Topics Report is the third in a series of reports chronicling the development of the FEMA 273 NEHRP Guidelines for the Seismic Rehabilitation of Buildings into the FEMA 356 Prestandard and Commentary for the Seismic Rehabilitation of Buildings. The purpose of this report is to provide a narrative discussion and permanent record of the technical changes made to Guidelines as the document evolved into the Prestandard. It is the vehicle by which new technical information was introduced into the Prestandard, as issues were identified and, when possible, resolved by the Prestandard Project Team. For completeness, this report also includes a brief discussion of new concepts introduced to the engineering profession in the publication of the original FEMA 273 Guidelines and FEMA 274 Commentary documents. As the Guidelines were used by the industry, questions arose regarding application of certain procedures, interpretation of some provisions, and results stemming from portions of the methodology. These questions have been formulated into statements, termed global issues, and recorded in this report for reference during the prestandard project and future revisions of the document. At the time the Guidelines were published, it was known that additional research was needed to refine the accuracy and applicability of certain procedures, and analytical studies were required to test and substantiate certain new concepts and philosophical themes. Unresolved issues, reported by BSSC to be present at the time of publication, are incorporated into this report and identified with the designation 'previously unresolved' in the classification of the issue. The purpose of Global Topics Report 1, Identification of Global Issues, dated April 12, 1999, was to formulate a statement and classify global issues that had been identified as of the date of the report. The issues identified in that report were presented and discussed at the ASCE Standards Committee Meeting on March 3, 1999, in San Francisco. The discussions resulted in clarifications to some of the issues, as well as a consensus on the recommended classification of each issue. Comments from Standards Committee members were incorporated into the report, and were used by the Project Team in moving issues toward resolution. Global Topics Report 2 was published on March 22, 2000. The purpose of the second report was to formulate statements for new global issues identified since Global Topics Report 1, and to document resolution of issues that were incorporated into the Second Draft of the Prestandard. This third and final Global Topics Report contains new global issues identified since the publication of the previous two reports, and final resolutions of previously identified issues. The appendices to this report contain the results of special focused studies, which serve as back-up data to the resolution of selected issues. These studies are referenced in the body of this report, where applicable, and included in the appendices for future reference. Upon completion of the Case Studies Project, the final report FEMA 343 Case Studies: An Assessment of the NEHRP Guidelines for the Seismic Rehabilitation of Buildings was made available to the Prestandard Project Team.