Seismic fragility assessment of self-centering hybrid precast walls subjected to mainshock-aftershock sequences

Abstract

This study primarily investigates the seismic fragility of mainshock damaged self-centering (SC) hybrid precast walls in aftershocks, and the results are compared with equivalent conventional reinforced concrete (RC) walls. A 5-story case-study structure is selected and designed comparatively using SC walls and RC walls to resist all the lateral seismic forces for design requirements. Thereafter, nonlinear time history incremental dynamic analyses (IDA) are conducted for the two analytical wall models using 44 artificially constructed seismic sequences. In the first step, mainshock IDA analyses are performed followed by aftershock IDA analyses considering different mainshock damages on the considered wall models. Three mainshock damage levels relating to three distinct post-mainshock inter-story drift ratios are induced in both wall models. The IDA curves in terms of maximum inter-story drift and residual drift are produced and comparatively studied for both wall models at predefined mainshock damage levels. The results are investigated and compared regarding seismic collapse capacity, residual drift, and effects of the polarity of aftershocks. It indicates from the study that in a general sense, the SC walls and RC walls exhibit similar collapse capacities for both undamaged conditions (i.e., subjected to mainshock only) and damaged conditions (with distinct mainshock damage levels). However, SC walls are intrinsically designed with significantly reduced residual drifts (proved again in this study), which results in much less influence from the aftershock polarity as compared to RC walls.