Experimental Study on the Seismic Performance of a Steel Slag CFDST T-Joint

In this paper, a kind of steel slag, concrete-filled double-skin steel tube (CFDST) T-joint is proposed to promote sustainable structural development. In order to examine the seismic performance of the steel slag CFDST T-joint, a series of hysteresis experiments were carried out on 4 CFDST T-joints with the main pipe under axial compression load and the brace pipe subjected to cyclic axial loading. The seismic performance of the CFDST T-joint was experimentally investigated in terms of the failure mode, load–displacement hysteresis relationship, stiffness degradation, energy dissipation and ductility. The effects of the hollow ratio and the steel slag concrete of the CFDST main pipe on the seismic performance of CFDST T-joint specimens were compared and analyzed. The experimental results show that the failure modes of the CFDST T-joint mainly included two kinds of failure, with those being main pipe fracture and joint area compression-bending failure. The seismic performance of the joints could be improved with a 12% ultimate bearing capacity and 54% ultimate deformation capacity with the hollow ratio of the CFDST main pipe increasing from 0 to 0.5. The seismic performance of the joints could be improved with a 54% ultimate deformation capacity by filling the steel slag concrete with a 0.5 hollow ratio.