Impact of Different Earthquake Types on the Statistics of Ductility Demand

Abstract

Probabilistic assessments of the seismic ductility demand for hysteretic bilinear single-degree-of-freedom systems have been reported in the literature. However, a systematic assessment of possible differences in the estimated ductility demand for different earthquake types using recorded ground motions is not available, although ground motion prediction equations for different earthquake types are developed. The assessment of the differences can be important for estimating structural reliability and expected damage cost under seismic excitations since partial damage and collapse could be related to the ductility demand. Therefore, if the differences are significant one must use consistent sets of ground motion prediction equation and ductility demand relation for each earthquake type affecting a site of interest to evaluate the seismic hazard and risk. To assess the differences of the ductility demand, 413 records for Mexican interplate earthquakes, 275 records for Mexican inslab earthquakes, and 592 records for California earthquakes are employed. The evaluation considers ranges of values of natural vibration periods and ratios of initial to postyield stiffness. The obtained results indicate that the statistics of displacement ductility demand differs for different earthquake types. The results are used to develop empirical relations for predicting the expected displacement ductility demand.