Assessment of seismic capacity and ductility of corroded RC shear wall-frame building

Abstract

In RC shear wall-frame buildings, shear walls provide substantial strength and stiffness to withstand the effects of strong seismic events. When situated near sea, seismic performance of these buildings reduces with time as they are commonly subjected to deterioration due to chloride ion ingress with subsequent rebar corrosion. In this study, the deteriorating effect of rebar corrosion on structural performance of a six-story RC shear wall-frame structure was studied taking into account the reduced bond strength, decreased reinforcement bar diameter, deterioration of steel’s mechanical properties, deterioration in the structural integrity of the concrete cover and a corresponding reduction in the confinement capacity of columns. Initially, the shear walls were independently analysed by modelling them using plane stress element micro-models. The capacity curves of the walls were then evaluated when subjected to 5 and 10% rebar corrosion implementing all the mentioned degradation factors due to corrosion. The six-story RC shear wall-frame structure was then modelled using a macro-model with shear walls modelled as a multi-linear nonlinear link element connected rigidly in the frames and beams along with columns as nonlinear moment hinges. The RC bare frame structure was also similarly modelled. Nonlinear pushover analysis of both the shear wall-frame and bare frame structure was then carried out without and with the effect of corrosion (5 and 10%). Results indicated that ultimate load capacity and ductility of both shear wall-frame building and bare frame building decreases with the increase in level of corrosion with more pronounced effect of corrosion on ultimate capacity of shear wall-frame building.