Experimental and theoretical analysis of PVC-CFRP confined steel reinforced concrete columns under axial compressive load

The PVC-CFRP confined steel reinforced concrete (PCSRC) is a composite structure formed by embedding steel inside PVC-FRP pipes and pouring concrete. It boasts advantages such as high bearing capacity, corrosion resistance, and the ability to withstand substantial plastic deformation. The PVC-FRP pipe is created by intermittently winding CFRP strips on the surface of a PVC pipe. To investigate the mechanical properties of PCSRC in short columns, 10 specimens under axial compression, varying different parameters including section diameter, steel content, yield strength of H-shaped steel, CFRP strip spacing, and concrete strength are designed. The test results revealed that the primary damage modes observed are PVC tube bursting and CFRP strips rupturing. The ultimate bearing capacity of the specimens increased with larger section diameters, higher concrete strength, increased yield strength of H-shaped steel, greater steel content, and narrower CFRP strip spacing. Moreover, as the concrete strength increases, the rate of degradation in axial compressive rigidity also accelerates, while the other parameters have relatively minor influences. Based on these experimental findings, a theoretical formula to predict the strength of PCSRC under axial compression is developed, and it aligns well with the experimental results.