Experimental and numerical study on cyclic behavior of a shape-optimized composite metallic yield damper with two-phase energy dissipation

Abstract

This paper proposed a novel shape-optimized composite metallic yield damper (SCMYD) consisting of an hourglass-shaped shear part and a K-shaped bending part in parallel. SCMYD is designed with the concept that only the shear part is activated under minor earthquakes and shear and bending parts work simultaneously under major earthquakes. The quasi-static test and finite element (FE) analysis were carried out to validate the shape optimization design and the seismic performance of SCMYD. Moreover, to obtain the reasonable design with superior seismic performance of SCMYD, the effects of the height to thickness ratio of the shear part (βs), the height to thickness ratio of the K-plate (βk) and the spacing ratio of the K-plate (γk) on the seismic performance were investigated by FE parametric analysis. Results indicated that the shape optimization could eliminate the stress concentration and allow a more uniform stress distribution in the damper. SCMYD enables two-phase energy consumption as expected and it demonstrates that the constraining effect of the bending part contributes to the combination effect of “1 + 1 > 2”. In addition, the parametric analysis results illustrated that reducing the βs is the most effective approach to improve the seismic performance while achieving the two-phase energy dissipation mechanism of SCMYD. It is recommended that the βs should be less than 28. Finally, a modified design formula for SCMYD considering the post-yield stiffness of the shear part is put forward, and an overstrength coefficient of 1.57 was suggested to estimate the ultimate loading capacity of SCMYD.