Abstract: In order to analyze the strain development law of the PVC-CFRP confined concrete column-RC beam exterior joints with core steel tube, through low cyclic tests of ten exterior joints with core steel tube(CST) and one typical joint. The effects of the steel ratio of the CST, stirrup ratio of the joint, axial compression ratio, longitudinal reinforcement ratio of the beam, and CFRP strips spacing were analyzed. The test results show that shear failure occurred at the joints, while no damage occurred at the PVC-CFRP confined concrete columns and beams. In the early stage, the shear force of the joint is mainly borne by the concrete; when the specimen bearing capacity reaches the peak bearing capacity, the diagonal pressure of the joint is still borne by the concrete, while the joint’s ring stirrups and the column’s longitudinal reinforcement jointly bear the diagonal tension. The CST can directly participate in the shear resistance. The calculating formula of the joint shear bearing capacity is proposed by considering the influence of the steel ratio of the CST, stirrup ratio of the joint, and axial compression ratio are considered, and introducing the comprehensive influence coefficient of joint shear resistance. The calculated results agree well with the experimental data.

Key words: PVC-FRP confined concrete, joint, concrete-filled steel tubular, failure mode, strain analysis, shear mechanism, composites