Theoretical Research and Numerical Analysis of a New Assembled Shuttle-Shaped Self-Centering Mild Steel Energy Dissipation Brace

To solve the problem of large residual deformation and high repair cost of traditional frame structures after an earthquake, a new type of assembled shuttle-shaped self-centering mild steel energy dissipation brace (ASSSEDB) with stable stiffness, material saving, and easy replacement was proposed. The plastic deformation of mild steel is used to dissipate energy, and the disc spring system provides a reset function. Based on the working mechanism of energy dissipation brace, a restoring force model for the ASSSEDB was established, and then the numerical analysis was carried out by ANSYS to verify the accuracy of the proposed model. The results confirm that the ASSSEDB has stable energy dissipation ability and a resetting function, with a full hysteresis curve. The finite element analysis results align well with the developed restoring force model, and the maximum deviations of initial stiffness and ultimate capacity are, respectively, 1.4% and 2.3%, which indicates that the established restoring force model can provide a theoretical basis for design of the ASSSEDB. Furthermore, the time history analysis was carried out to assess the seismic performance of a six-story steel frame structure using the proposed ASSSEDB. The results show that compared with the steel frame structure with BRBs, the proposed ASSSEDB can decrease the residual deformation of structures by up to 93.41%. The self-centering ratio of the ASSSEDB is crucial in controlling residual deformation of structures, and it is recommended to be greater than 1.0.