Seismic behavior of resilient composite steel plate shear wall using experimental investigations

Using composite encased steel plate shear wall (C-SPSW) has been attractively raised for enhancing the lateral seismic performance and increasing the useful floor area. Although, the experimental investigations have proved excellent dynamic behavior of C-SPSWs, structural damage as well as residual displacements are the main disadvantages of C-SPSWs, which are not consistent with low damage design (LDD) approaches. In the current study, the C-SPSWs performance is improved using the self-centering (SC) technique to control the both structural damage and reduce residual displacements as well. Five tests on C-SPSWs including three SC composite encased steel plate shear walls (SC-C-SPSWs) were conducted under gravity and lateral cyclic loads. The SC-C-SPSW consists of C-SPSW equipped with unbonded posttensioned tendons (UPT) to have resilience ability. For this aim, two symmetrical gaps were provided at the ends of the wall, and the UPTs were mounted at the wall ends and crossed into the foundation through the middle of the gaps. Under lateral load, the gap opening allows the elongation of UPTs that induce a high restoring forces, forcing the wall to have rocking movement above the foundation. In comparison with C-SPSWs, the SC-C-SPSWs exhibited low damages, higher shear strength capacity between 28% and 35%, larger ultimate drift capacity and more displacement ductility as 45–136% in average. Furthermore, the SC ability and the UPTs restoring forces effectively reduced the residual drift and the SC moment causes the recovery of the residual drift between 90% and 105%. Moreover, compared to C-SPSWs, the residual lateral strength of SC-C-SPSWs was improved by 30% in average.