A concrete-filled steel tube (CFST) column has the advantages of high bearing capacity, high stiffness, and good ductility, while reinforced concrete (RC) structure systems are familiar to engineers. The combinational usage of CFST and RC components is playing an important role in contemporary projects. However, existing CFST column-RC beam joints are either too complex or have insufficient stiffness at the interface, so their practical engineering application has been limited. In this study, the results of a practical engineering project were used to develop two kinds of CFST column-RC beam joints that are connected by vertical or U-shaped steel plates and studs. The seismic performance of full-scale column-beam joints with a shear span ratio of 4 was examined when they were subjected to a low-cyclic reversed loading test. The results showed a plump load-displacement curve for the CFST column-RC beam joint connected by steel plates and studs, and the connection performance satisfied the building code. The beam showed a bending failure mode similar to that of traditional RC joints. The failure area was mainly concentrated outside the steel plate, and the plastic hinge moved outward from the ends of the beam. When the calculated cross section was set at the ends of the beam, the bending capacity of joints with the vertical or U-shaped steel plates and studs increased compared to the RC joint. However, when the calculated cross section was set to the failure area, the capacity was similar to that of the RC joint. The proposed joints showed increases in the energy dissipation, average energy dissipation coefficient, and ductility coefficient compared to the RC joint.
Mechanical Properties of Strengthened RC Beams using Steel Plates