Finite Element Analysis on Weak PVC-FRP Confined Concrete Column and Strong Joint Strengthened with Core CFST Under Axial Compression

In this paper, the axial compression behaviors of the PVC-FRP confined concrete (PVC-FRP-CC) column-RC beam joint strengthened with core concrete filled steel tube (CFST) were examined through a series of experiments, in which 11 specimens were conducted under axial load. Experimental parameters included the length of core steel tube, the height of joint, the stirrup ratio of joint, the steel ratio of core CFST and the spacing of CFRP strips. Test results indicated that all the specimens failed with column failure. The decrease in the height of joint or the spacing of CFRP strips increased the ultimate bearing capacity and yield capacity of the specimens, while the effect of other parameters was not obvious. After the specimens yielded, the decrease in spacing of CFRP strips slowed the stiffness degradation, while the decrease in stirrup ratio of joint or steel ratio of core CFST accelerated the stiffness degradation. On the basis of the experimental research, a finite element (FE) model was established by selecting reasonable constitutive relation of the materials, and the loading process of the specimens was simulated to reveal the working mechanism of the column-beam joints. What was more, parametric studies were further carried out based on the developed FE model, and some constructive measures were proposed.