Development and seismic performance of bolted steel dampers with X-shaped pipe halves

Abstract In this paper, a modified pipe damper design which called X-shaped pipe damper (XPD) is proposed. The damper is fabricated by connecting two oppositely positioned pipe halves to form a X-shaped core, which is then bolted to connecting plates. The bolted XPDs are replaceable and can be conveniently fabricated at low costs. Cyclic tests were performed on 5 bolted XPDs and 2 welded XPDs to investigate the strength development patterns, hysteretic performances, energy dissipation abilities and failure modes. The bolted and welded XPDs were also applied to the seismic retrofit of a 6-story steel frame to investigate the performance of new dampers on the seismic response control. Experimental results indicated that the bolted XPDs can provide good ductility and stable hysteretic relations under both standard cyclic protocol and fatigue cyclic protocol. The connected pipe halves can successfully form tensile bracing modes and induced secondary strength increases at large lateral displacements. The welded XPDs possessed weaker energy dissipation capacity due to early fracture failures, but they can provide higher stiffness and yielding strength. The bolted XPDs presented good dynamic response controlling performance under both medium level and high intensity level earthquakes.