Experimental study of a steel damper with X-shaped welded pipe halves

Abstract In this paper, a new steel damper named X-shaped pipe damper (XPD), is proposed and examined. The proposed damper is made through welding two oppositely positioned pipe halves to form a X-shaped core, and connecting the X-shaped core to side plates with fillet welds or circumferential welds. The XPD damper provides the lateral resistance and energy dissipation behaviors initially through flexural bending of pipe plates, and latter through the tensile stretching at composite pipe halves. Theoretical derivations of initial stiffness and yielding properties were conducted, and the nonlinear working mechanisms and seismic performance were investigated through cyclic quasi-static tests. Effect of welding methods and pipe configurations on the stiffness, strength, ductility and energy absorption efficiency of the XPDs were studied. The XPDs can presented similar lateral load resistance with only half pipe usage than dual pipe dampers. The XPD specimens all presented stable and pump hysteretic loops, and had a steady strength increase after yielding until fracture failure. The circumferential weld XPDs displayed higher initial stiffness, strength and better deformation ability than the fillet welded ones, but also possessed fatigue fracture potential at the heat affecting zones under fatigue cyclic protocols. Based on the obtained results, the application field and improving suggestions for the XPDs are discussed.