Finite element analysis of the seismic behavior of concrete-filled PVC-CFRP tubular column-RC beam cross-joints connected with core steel tubes

Based on experimental study on the cross-joints of concrete-filled PVC-CFRP (Polyvinyl Chloride-Carbon Fiber Reinforced Plastics) tubular column-RC (Reinforced Concrete) beam connected with core steel tubes, this study selects appropriate constitutive relations of materials and failure criteria, and establishes a finite element model using ABAQUS software to investigate the seismic mechanical behavior of such joints under low-cycle reversed loading. The hysteretic curve and skeleton curve derived from finite element simulation are in good agreement with the experimental results, proving the validity of the finite element model. Based on this, the study analyzes the stress distribution of the concrete in the joint area and the inner and outer concrete of the core steel tube in the loading process, and explores the ultimate failure mode of such joints. Finally, the experimental parameters are extended to study the effects of concrete strength grade, core steel tube radius-thickness ratio, joint area stirrup ratio, and axial compression ratio on the skeleton curve and stiffness degradation of the joint. The stress mechanism of the joint under low-cycle reversed loading is analyzed, and relevant design and structure requirements are proposed to provide a reference for the experimental design and engineering application of this type of joint.