Experimental Study on the Seismic Performance of 3D Joints between Concrete-Filled Square Steel Tubular Columns and Composite Beams

Six three-dimensional (3D) joints between concrete-filled square steel tubular columns and composite steel-concrete beams were tested under bidirectional reversal loads. The primary purpose of this experiment was to investigate the seismic performance of these composite joints, including load-deformation performance, hysteretic behavior, failure modes, and damage patterns, emphasizing the effects of loading history, connection details, and joint geometries. The test specimens exhibited good strength and stiffness retention capacities and excellent energy dissipation. The typical failure mode of the specimens was shear damage of the joint panel. The influence of the bidirectional loading was minor during the initial response of the joint in elastic range; however, it became significant when the joint was loaded into plastic range. The composite action between steel girder and concrete slab enhanced the capacity of the joint in terms of ultimate strength, stiffness and ductility. Concrete encased in the steel tubular column improved the seismic performance of the joints.