Experimental Study on the Axial Compression Performance and Bearing Capacity Calculation Method of Concrete Filled CFRP-PVC Square Tube Column

To explore the mechanical characteristics of carbon fiber reinforced polymer-polyvinyl chloride (CFRP-PVC) square tube confined concrete columns, a set of nine specimens was meticulously crafted, varying in parameters such as the quantity of CFRP layers as well as the width and spacing of CFRP strips. Axial compression tests were conducted to gauge the response of the specimens under stress. Detailed observation of the complete failure process yielded crucial parameters including axial load displacement, peak bearing capacity, ductility coefficient, and axial compression stiffness. The results unveiled distinct failure patterns: specimens under strong restraint exhibited tearing failure at the corners of the CFRP-PVC tube, whereas those with weaker restraint experienced buckling failure of the PVC tube. Moreover, adding a greater number of CFRP layers led to a substantial 46.7 % growth in maximum peak bearing capacity, albeit at the cost of a 34.5 % reduction in ductility. Similarly, widening the CFRP strip resulted in a significant 41.8 % boost in maximum peak bearing capacity and a 9.6% growth in ductility, surpassing those of specimens lacking CFRP. Remarkably, among specimens with equivalent CFRP content, those featuring CFRP strips spaced at 50 mm and with a width of 50 mm showcased superior mechanical properties. The finite element analysis adeptly replicated the observed cracking behavior. Drawing from the experimental findings and established literature calculation methods, a robust method for determining the axial compressive bearing capacity of CFRP-PVC square tube confined concrete columns is proposed.