Polyvinyl chloride (PVC)-carbon fiber reinforced polymer (CFRP) confined concrete (PCCC) columns shows considerable engineering application prospects due to their excellent corrosion resistance, high bearing capacity, favorable seismic behavior and reasonable price. The research on the connection between PCCC columns and reinforced concrete (RC) beams is an essential aspect to facilitate the development and application of this novel composite structural system. In this study, thirteen PCCC column-RC beam interior joints reinforced with core steel tube (CST) (hereinafter referred to as PCCCC-RBIJs-CST) are designed and tested under low cyclic loading. Several parameters, such as stirrup ratio of joint ( \(\rho_{sj}\) ), diameter-thickness ratio of CST ( \(d_{s} /t_{s}\) ), axial compression ratio of column ( \(n\) ), spacing of CFRP strips ( \(s_{{\text{f}}}\) ), reinforcement ratio of beam ( \(\rho_{b}\) ) and reinforcement ratio of column ( \(\rho_{c}\) ), are considered. All the specimens show large plastic deformation, culminating in shear damage in the joint core area. The failure mode is characterized by crushing of concrete, yielding of stirrups, CST and reinforcement in the joint area. The hysteresis curves are relatively full, and the shape of curves gradually change from shuttle shape to bow shape and eventually to anti-S shape. The impacts of the studied variables on strength, stiffness, energy dissipation capacity and ductility are systematically analyzed and the feasibility of connecting PCCC columns and frame beams by means of built-in CST reinforcement is verified. Subsequently, the shear capacity of PCCCC-RBIJs-CST is evaluated by using four different existing shear capacity formulas. The reasons for deviations between the predicted results and the measured test data are deeply elaborated. A relatively reasonable predicted formula is suggested.
