Method of Reliability-Based Seismic Design. II: Calibration of Code Parameters

Abstract

This is the second part of a two-part investigation on the method of a reliability-based seismic design. To account for large uncertainties in structural design under seismic load, a method of calibration of the design parameters in seismic codes is proposed based on the consideration of satisfactory performance under future earthquakes in terms of reliability. The calibration is carried out by a minimization of the difference between target and actual reliabilities against serviceability and ultimate limit states over a given period of time. The response surface method (RSM) in conjunction with a central composite design is used to expedite the minimization solution process. To reduce the computational effort required for reliability evaluation under seismic loads, the equivalent nonlinear system (ENS) developed in part I is used for dynamic-response analysis of multi–degree-of-freedom (MDOF) inelastic structures. Numerical examples on the calibration of the earthquake load factor and drift limit for selected target limit-state probabilities are given. Parametric studies are also carried out to examine the dependence of these parameters on the target reliability levels against both serviceability and ultimate limit states.