Probabilistic Seismic Safety Assessment of Chinese RC Frame Structures Using Fragility Curves

Abstract

A simulation-based procedure was adopted to generate fragility curves for five Chinese-code conforming reinforced concrete (RC) frame structures with increasing design-based earthquake (DBE) intensities. Two important elements, namely probabilistic seismic demand analysis (PSDA) and probabilistic seismic capacity analysis (PSCA), were involved in the procedure. In PSDA, 100 real ground motion records were selected to perform nonlinear time history analyses for representing the influence of earthquake uncertainties on structural demands. In PSCA, a group of ten structural parameters were considered as random and then the conventional (deterministic) pushover analysis was extended by introducing 100 building samples according to the principle of the Latin hypercube sampling technique. From the derived pushover curves, the thresholds corresponding to the limit states, namely “slight damage”, “moderate damage”, “extensive damage” and “complete damage”, were obtained for statistics. Finally, fragility curves were generated through combining the results of PSDA and PSCA, and the exceeding probabilities of the example frames conditioned on the three mostly concerned earthquake levels, i.e. FE (frequent earthquake), DBE and MCE (maximum considered earthquake), were consequently calculated. The results show that the increase of fortification earthquake intensity cannot correspondingly promote the probabilistic safety level.