Investigation of the performance of the self-centering steel plate shear wall considering stress relaxation in pre-stressed cables

Self-centring systems are one of the novel earthquake-resistant systems that can eliminate permanent earthquake-induced damage in buildings. In these systems, damage can be limited to those members that can be easily replaced after earthquakes. Self-centring steel plate shear walls (SC-SPSW) with pre-stressed cables combine the lateral load-resisting capacity of conventional SPSWs with the self-centring capabilities of PT beamto-column connections and provide sufficient ductility and stiffness for the system. The stress relaxation phenomenon in pre-stressed cables can lead to stress reduction in cables with the passage of time. This phenomenon should not be neglected. In this study, the self-centering steel plate shear wall is simulated using finite element (FE) modeling and verified based on available experimental results; then, the effect of stress relaxation on stiffness and energy dissipation capability of the system is evaluated at different initial pre-stressing forces and time intervals. According to the results, after five years and for cables with a pre-stressing ratio of 0.7, the stiffness and dissipated energy have reduced by 26 and 5 percent, respectively, in comparison to the time just after pre-stressing. These values was 40 % and 2 % for stiffness reduction and energy dissipation capacity reduction, respectively when the cables were pre-stressed with the pre-stressing ratio of 0.9. Furthermore, A method is also suggested to improve the seismic performance of the self-centering connections which includes employing low yield point steel in energy dissipater devices. Results showed that the energy dissipation capacity of the system doubles by using low-point steel for the web plates. The cumulative dissipated energy was about 1.044 MJ with A1008 steel and it was increased to 2.058 MJ with LYP100 material. This increase was mostly observed after the 10th cycle of the hysteresis curve.