Seismic Qualification, Fragility Testing, and Evaluation of Suspended Ceilings

摘要

Past earthquakes have demonstrated the vulnerability of nonstructural components to seismic events. In the previous editions of the building codes, little emphasis was placed on nonstructural components, partly because these components are not easily analyzed, if at all, and partly because of the lack of familiarity by practicing structural engineers with prefabricated systems usually designed by other engineering professionals. However, due to their higher cost and effect on loss of operation, these components are often critical to a building's overall seismic performance. With the advent of performance-based earthquake engineering and the publication of FEMA 356, seismic performance guidelines for nonstructural elements have been established. The new edition of the building code, IBC 2006, explicitly addresses these components. In lieu of analysis, evaluation by means of earthquake simulator testing is now allowed. However, specific test and acceptance guidelines are still evolving. One of the critical nonstructural components that could experience major damage during earthquakes and cause potential life safety hazards is the suspended ceiling. Industry standards were developed in the 1980's, in part based on the test results from a set of earthquake simulation tests. Empirical reconnaissance data from recent earthquakes were then used to advance these standards. However, no vigorous evaluation of the suspended ceilings had been performed, nor the critical parts or modes of failure of these units had been identified. Representatives from the suspended ceiling industry, academia, and structural engineering profession have collaborated to address these issues. Additionally, the partnership undertook the following: 1) to evaluate the current test methodologies and correlate the test data with past seismic performance, 2) to prepare test-derived fragility data and relate to the standards, 3) to prepare recommendations for improvements to the current test methodology and acceptance procedure, and 4) to identify areas of future research and investigations. Preliminary findings from this joint effort are presented in this paper.