Seismic performance evaluation of a novel shape-optimized composite metallic yielding damper

A novel shape-optimized composite metallic yielding damper (SCMYD) is proposed to improve the energy dissipation capacity under multiple levels of earthquakes. The SCMYD was developed by combining the shear and the bending part in parallel, where the bending part is arranged symmetrically on both sides of the shear part to restrain the out-of-plane deformation under large displacements. In SCMYD, the yielding of the shear part is designed to consume seismic energy under minor earthquakes, while the collective plastic deformation of the shear and bending parts are used to dissipate inputting energy under major earthquakes. In addition, the shear and bending parts were shape-optimized to improve fatigue performance and material utilization. The corresponding design formulas of the SCMYD were also derived. Furthermore, the effectiveness of the optimization and the seismic performance of the SCMYD were evaluated by the cyclic loading test in terms of failure mode, combined hysteretic behavior, and energy dissipation. Additionally, the effect of the yield load ratio of the shear part (β) on the seismic performance of the SCMYD is discussed. Results demonstrated that the shear and bending parts are able to achieve a uniform stress distribution after optimization, while the design formula is also available for the preliminary design of SCMYD. Compared to conventional metallic yielding dampers, the SCMYD is superior with regard to hysteresis stability, loading and energy dissipation capacity. Besides, the SCMYD is capable of consuming energy under both minor and major earthquakes as intended and exhibits desirable seismic performance when the β value is 0.4. The research findings are expected to provide a reference for the design and real-world applications of the SCMYD.