Development of fragility curves for self-centering bae-rocking walls subjected to far and near field ground motions

Nowadays, modern lateral-resisting systems capable of reducing residual displacements and post-earthquake costs have gained much more attention. Self-centering lateral load-resisting systems reduce repair costs and allow immediate occupancy by concentrating damages on fuse elements. Self-centering base-rocking concrete shear wall (SC-BRW) is one of the innovative self-centering seismic systems. In the present study, the probabilistic behavior via fragility curve of this system was investigated under three sets of seismic records including 22 Far-Field (FF) ground motions and 28 Near-Field (NF) ground motions half of which are Pulse-like (Pulse). These ground motions were used for nonlinear incremental dynamic analysis of structures with 4, 8, 12, 16, and 20 floors. Numerical modeling was conducted via OpenSEES software in a two-dimensional space. The results of fragility curves showed that short SC-BRWs subjected to NF-Pulse ground motions and tall SC-BRWs subjected to Far-Field (FF) and NF without Pulses (No Pulse) ground motions were more vulnerable. Due to the effects of high modes, the values of moment and shear in the middle of the height than the base of the structure increased with increasing the height of the structures. Increased moments in the middle height compared to the base are observed in tall walls under FF and NF-No Pulse ground motions. Also, increase in the moments is not observed in the case of short and tall SC-BRWs subjected to NF-Pulse at the mid height. The increased moment of the wall of a 20-story SC-BRW subjected to FF and NF-No Pulse ground motions at the level of CP performance is 46 and 39%, respectively. According to the results of the analyses, the residual inter-story drift values for SC-BRWs are negligible. In this respect, the maximum amount of residual inter-story drifts in the 20-story structure under far-field ground motions was about 0.0011 at the CP performance level. Finally, the NF-Pulse ground motions created a greater stress ratio than other seismic records in prestressed tendons.