Reliability functions for earthquake resistant design

A unified approach is presented for the establishment of design conditions and acceptance criteria for performance objectives associated with differen t return intervals. A life-cycle optimization analysis is adopted for this purpose. Reliability and expected damage functions are defined both for ind ividual seismic events and for a long-term framework. System reliability fu nctions are determined by Monte Carlo simulation for a number of multistory frames, designed for different base-shear ratios and subjected to earthqua kes of different intensities. Systematic trends are identified about the va riation of the reliability index with the natural logarithm of the expected ductility demand of a reference system. These trends lead to the definitio n of seismic reliability functions that can easily be adapted for applicati ons to reliability-based design. The problem of transforming the results of the optimization studies into codified rules for practical design is brief ly discussed. (C) 2001 Elsevier Science Ltd. All rights reserved.