Development and experimental study of a replaceable double stage coupling beam damper

A double stage coupling beam damper (DSCBD) was proposed and tested in this paper. The DSCBD comprises a viscoelastic damper and a metallic damper connected in series. Deformation of the DSCBD in the first stage was concentrated on the viscoelastic damper, which provided initial stiffness and energy dissipation capacity. With the increase in displacement and the initiation of the second stage, the deformation of the viscoelastic damper was constrained by the limiting mechanism and triggered the deformation concentrating in the metallic damper. These further increased the stiffness and energy dissipation capacity and the DSCBD exhibits the double stage behavior. The DSCBD proposed in this paper can simultaneously satisfy the seismic requirements of the main structure under different levels of seismic excitation, without installing different types of traditional dampers to achieve the same effect. A performance-based design method was proposed. Two full-scale DSCBD specimens were subjected to quasi-static multi-stage cyclic loading tests to investigate the effects of different aspect ratios. The test results showed that DSCBD with an aspect ratio of 3.2 exhibited ideal shear failure mode, and the minimum equivalent viscoelastic damping ratio in the second stage was 22.58 %, while the DSCBD with an aspect ratio of 4.4 exhibited unexpected bending failure mode, and the maximum equivalent viscoelastic damping ratio in the second stage was 19.42%. In addition, the DSCBD with an aspect ratio of 3.2 showed better low-cycle fatigue capacity, whose degradation of bearing and energy dissipation capacities can be controlled within 5% after 30 additional loading cycles. The accuracy and the correction scheme of the design method were verified by the test results.