Strain analysis of PVC-CFRP confined concrete column with ring beam joint under axial compression

To study the mechanical characteristics of PVC-CFRP confined concrete column with ring beam joint (PCRCJ), the experiment of nine PCRCJ specimens and one PVC confined concrete column with ring beam joint (PRCJ) subjected to axial compression, which were designed with the concept of strong connection joint and weak column, was performed in this study. Different parameters, such as the height and width of ring beam, reinforcement ratio and stirrup ratio of ring beam, and CFRP strip spacing, were considered. The PRCJ was destroyed due to the buckling of PVC tube while the failure mode of the PCRCJ was characterized by the cracking of PVC tube and fracture of CFRP strips. The ultimate strain of the PVC-CFRP confined concrete column decreased as the CFRP strip spacing increased. The height, width, stirrup ratio, and reinforcement ratio of the ring beam had no obvious influence on the ultimate strain of the column. The ultimate strain of the joint decreased as the height, width of the ring beam, or CFRP strip spacing increased. The variation of the stirrup ratio and reinforcement ratio of the ring beam had no significant influence on the ultimate strain of the joint. Models for estimating the stress-strain curves of the PCRCJ were proposed, and they agreed well with test data.