Experimental study on the mechanical properties of concrete canvas and CFRP jointly confined circular concrete columns under axial compression

Concrete canvas (CC) has good corrosion resistance and fire resistance, but it is rarely used in civil engineering. In this study, CC and carbon fiber-reinforced polymer (CFRP) are jointly used to reinforce concrete columns (i.e., jointly confined specimens) to expand their engineering application. To explore the axial compressive perfor-mance of combined CC-CFRP confinement concrete columns, 13 sets of specimens were designed in this study based on the number of CFRP layers, number of CC layers and volumetric stirrup ratio. The conclusions are as follows: 1) based on acoustic emission (AE) technology, the presence of CC can improve the uneven deformation of the concrete, and the jointly confined specimen has better energy dissipation capacity; 2) based on the experimental data, the peak stress of the jointly confined specimen is reduced by up to 10 % compared with the CFRP-confined specimen (i.e., the single confined specimen), and the ultimate strain is increased by at least 56.2 %, which shows that the jointly confined method is reasonable and feasible; and 3) the peak stress and ultimate strain models of the jointly confined specimen are obtained by numerical fitting, and a stiffness-based design-oriented compressive stress-strain model for the jointly confined specimen is proposed. Compared to existing models, the proposed model has higher accuracy, which can provide a theoretical basis for further research.