Experimental and theoretical research on a shear-bending-metallic-damper with a double-phased yield mechanism

Aiming at improving the performance and practicability of metallic dampers, this paper proposes a novel shear-bending metallic damper with a double-phased yield mechanism (SBD-DY) by setting bending and shear plates with different yield strengths in parallel. The double-phased yield mechanism enables the damper to provide proper energy dissipation ability and stiffness for the primary structures during various earthquakes. Design methods of SBD-DY, including the elastic stiffness, the yield strength, the yield displacement, the force-displacement relationship and the membrane effect, are proposed. Ten SBD-DY specimens are tested under monotonic and cyclic loading to verify the workability of the bending and shear plates. The test results reveal that the SBD-DY specimens demonstrate satisfactory plastic development with full hysteresis curves, favorable energy dissipation ability and good ductility. Two types of failure modes, namely the weld failure of bending plates and fracture of strips, are summarized. Test specimens with fracture of strips exhibit better residual load capacity and energy dissipation ability than specimens with weld failure of bending plates. The effects of parameters including width of bending plates (B), height of bending plates (H) and width of the strips (S) are compared and analyzed. The theoretical results agree well with the experimental results, clearly revealing the double-phased mechanism of SBD-DY. Finally, potential improvements are also proposed to avoid premature weld failure of SBD-DY.