Probability-Based Seismic Assessment of Buildings,considering Post-Earthquake Safety

Abstract

Advanced Seismic Assessment Guidelines, developed by researchers at Stanford University and tested by the authors, offer improvement over previous methods for seismic evaluation of buildings where post-earthquake safety is a concern. This probability-based method allows engineers to quantify expected structural performance in terms that are meaningful to building owners. Performance levels quantified in the Guidelines range from “No Damage” to “Collapse” and include intermediate performance levels based on the post-earthquake occupancy classifications “Green Tag,” “Yellow Tag,” and “Red Tag.” Other features of the Guidelines include an emphasis on correctly identifying the governing mechanism of nonlinear behavior, practical methods for addressing the effects of strength degradation and residual drift, and a probability-based approach that incorporates uncertainty. Based on their studies of example buildings, the authors present recommendations for performing seismic assessments: quantifying post-earthquake occupancy classifications, identifying mechanisms of nonlinear behavior, estimating residual drift, and modeling strength degradation in structures.