Variability of near‐fault seismic risk to reinforced concrete buildings based on high‐resolution physics‐based ground motion simulations

Abstract

AbstractBroadband physics‐based simulated earthquake ground motions are utilized to characterize the regional‐scale seismic risk to modern reinforced concrete (RC) structures. A highly dense dataset of ground motions covering a 100‐km 40‐km domain was generated using kinematic fault rupture models with varying rupture characteristics to represent shallow crustal earthquakes and resolved up to frequencies of 5 Hz. Over 40,000 nonlinear response history simulations of short‐ and mid‐rise RC special moment frame buildings were conducted using simulation models that are capable of representing nonlinear behavior and component deterioration effects. The spatial variability of structural risk within a single earthquake scenario and between different rupture scenarios is examined, and the regions of strongest directivity effects and highest structural demands are identified. The structural demands may vary by factor of up to 8.0 at very short distances from the fault, and the large dispersion in the demands decreases significantly beyond a distance of 15 km. The interstory drift and member rotation demands are substantially impacted by important features of the geological structure and the characteristics of the rupture scenarios, particularly the presence of localized high‐slip regions. The frequency characteristics of the structures are found to play an important role in determining the effects of near‐fault ground motions on the structural response and expected damage. The results of this study suggest that the simulated ground motions, particularly those generated using the hybrid rupture approach, may offer reasonable structural risk estimates for low‐frequency structures and conservative estimates for high‐frequency structures.