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This study proposes the development of a magnetorheological self-centering brace (MR–SCB) that can improve the energy dissipation capability of SCBs. The proposed brace reduces residual deformation and enhances the seismic performances of the structure. The disc springs enable recentering capability, while the magnetorheological fluid dissipates energy. The mechanics of the MR–SCB are presented, and a restoring force model to describe its hysteretic responses is established. Cyclic tests were conducted on the magnetorheological damping components of the brace and the entire large-scale MR–SCB specimens under sinusoidal excitations. Results confirm that the MR–SCB exhibits full flag-shaped responses, high ultimate bearing capacity, special superior energy dissipation capability, and stable restoring force. In addition, the proposed MR–SCB eliminates 96% of residual deformation. The superior energy dissipation capability of the MR–SCB can dissipate more energy and achieve greater control of seismic responses. The predicted and experimental results agree well. Thus, the Bouc–Wen restoring force model can be used to accurately describe the force–displacement behavior of the MR–SCB.

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The ability of an idealized piecewise-linear restoring force model and a nonlinear mechanical model to describe the hysteretic performances of the pre-pressed spring self-centering energy dissipation braces was evaluated based on experimental data. The hysteretic behaviors predicted by these two proposed models were compared with the experimental results of a typical prototype brace, and the results demonstrated that the two models can explain the brace force-time responses, and that the nonlinear mechanical model is more effective in describing the stiffness transition and energy dissipation of the brace. The two proposed models can be used for the design of the pre-pressed spring self-centering energy dissipation brace specimens, and the nonlinear mechanical model may be more useful for designing the structures with the pre-pressed spring self-centering energy dissipation braces. An orthogonal experiment was applied to analyze the influences of the key parameters on the performances of pre-pressed spring self-centering energy dissipation braces based on the nonlinear mechanical model. The results indicate that the friction slip force of energy dissipation mechanism, the pre-pressed force of self-centering mechanism, and the post-activation stiffness significantly affect the hysteretic performances and equivalent viscous damping ratios of the bracing system, while the changes in other parameters only produce slight effects. The determination of the pre-pressed force of the self-centering mechanism should be coordinated with the friction slip force of the energy dissipation mechanism to achieve a better hysteretic performance of the pre-pressed spring self-centering energy dissipation brace.

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