Near fault ground motion effects on seismic resilience of frame structures damaged in Wenchuan earthquake

Abstract

This paper reports the study of the effects on structural seismic resilience of near fault pulse-like ground motions recorded in the 2008 Wenchuan earthquake. Some near fault pulse-like and far fault nonpulse-like ground motions recorded in the Wenchuan earthquake were selected as excitations for nonlinear dynamic analysis. A low-ductile reinforced concrete frame and a modern ductile frame were considered to compare seismic resilience of frames constructed before and after the Wenchuan earthquake. The building-based loss evaluation approach in HAZUS was modified to explicitly consider the effect of residual story drifts, which provides an accurate loss evaluation method and still retains simplicity. Fragility curves were derived from incremental dynamic analysis. Loss vulnerability curves for frames were obtained based on the proposed method. Functionality restoration curves and resilience index were then estimated. The results show that the Wenchuan near fault pulse-like ground motions can induce higher collapse and demolition risks for frames. Total losses of frames are higher under pulse-like ground motions, and the resilience of frames is reduced. Ignoring residual story drifts will underestimate total losses, especially for frames under pulse-like ground motions. Finally, the modern ductile frame shows enhanced earthquake resilience compared with the low-ductile frame.