ASCE/SEI 7‐compliant site‐specific evaluation of the seismic demand posed to reinforced concrete buildings with real and simulated ground motions

Abstract

AbstractState‐of‐the‐art seismic design and assessment methodologies rely on the utilization of ground‐motion records scaled to site‐specific risk‐targeted spectra to perform nonlinear time‐history analyses and estimate mean structural demands. Motivated by the discrepancies in structural response estimates resulting from different selection and scaling methods, this study assesses the implications of utilizing site‐specific simulated ground motions from 3‐D physics‐based wave‐propagation models as opposed to historical records from worldwide catalogs in ASCE/SEI7‐compliant procedures for seismic performance evaluations. A suite of validated realizations of an M7 Hayward Fault earthquake in the San Francisco Bay Area and two modern reinforced concrete moment‐resisting frame buildings are utilized as a case study. The 2014 USGS earthquake hazard and probability maps are employed for the hazard calculations, and the PEER NGA‐West2 database is used for the selection of the real ground motions. The building models are coupled with the simulated and real ground motions to perform a total of 30,552 nonlinear time‐history analyses. Structural demands obtained from real and simulated motions are examined and compared at the regional‐scale in terms of peak interstory drift ratio median and dispersion, and localization along the building height. The correlations between observed structural responses and ground‐motion features are discussed to potentially inform current code‐compliant methodologies for ground‐motion selection. Results show that utilizing site‐specific simulated ground motions that incorporate path, fault geometry, and site‐condition effects as opposed to historical ground‐motion records may lead to differences in the structural demands above 50%. Such differences are highly spatially variable throughout the region and difficult to predict.