Cyclic loading test for concrete-filled U-shaped steel beam–RC column connections

Concrete filled U-shaped steel beams are used to increase the flexural strength and stiffness of the steel beams by using concrete fill. In this study, a seismic detail for the concrete filled U-shaped steel beam–RC column connection was developed. A special detail using diagonal re-bars and welded re-bar connections was used to strengthen the beam–column joints. To verify the seismic performance of the beam–column connection, two full-scale specimens were tested under cyclic loading. The test parameter was the size of the U-shaped steel beam. The depths of the composite beams were 610 mm (steel plate thickness = 6 mm) and 710 mm (steel plate thickness = 8 mm) including the slab depth of 160 mm. The test results showed that the specimens exhibited good strength, deformation, and energy dissipation capacities. The deformation capacity exceeded 4% inter-story drift ratio. The primary failure mode of the specimens was buckling and fracture of the steel plate in the beam.