Experimental and numerical study on the seismic performance of a new self-centering brace with S-shaped steel plate dampers

This paper proposes a new self-centering brace with S-shaped steel plate dampers (SCBSSPD) that integrates two pre-compressed disc-spring stacks for self-centering and two SSPDs for energy dissipation, achieving a conveniently inspectable system with multi-function of load-bearing, energy dissipation, and multi-level seismic response control. The construction details and working principle of the SCBSSPD are expounded, followed by the derivation of theoretical design formulas. Two full scale SCBSSPD models are fabricated and tested under eight cyclic loading cases considering various pre-compression forces and SSPD dimensions. The damage mode, hysteretic behavior, energy dissipation and residual displacement are analyzed to assess the seismic performance and recoverability. Subsequently, 3D numerical modelling approach for the SCBSSPD is presented and experimentally validated, following which the effects of crucial parameters on the seismic performance are discussed by conducting substantial simulations. Furthermore, a macro numerical model is proposed and developed into OpenSees platform for facilitating the simulation of the SCBSSPD. The results show that the new device has flag-shaped hysteretic responses with stable energy dissipation capacity and excellent self-centering capacity. The 3D numerical simulations confirm its capacities of large load-bearing and multi-level seismic control of the new device. The parametric studies suggest the ratio of pre-compression force to yielding strength of the dampers to be within 1.0 ~ 1.5, and the ratio of their initial stiffness to be less than 0.5, for realizing rational distribution of energy dissipation and reducing residual deformation by 90%. The theoretical design formulas and macro numerical model present results in good agreement with those of the experiments, which can be used for the design and nonlinear dynamic analysis of structures equipped with the SCBSSPD.