Confinement behavior and stress-strain response of square concrete columns strengthened with carbon textile reinforced concrete (CTRC) composites

In this study, with the aim of investigating the confinement behavior and stress-strain response of concrete columns strengthened with carbon textile reinforced concrete (CTRC) under a uniaxial load, a total of 20 column specimens with square cross-sections were cast and subjected to monotonic axial compression. Next, the effects of the number of textile layers, stirrup reinforcement ratio, concrete strength and short fibers on the efficiency of CTRC confining system were evaluated. The experimental results indicated that the CTRC-confined columns obtained a maximum improvement of up to 67.3% in bearing capacity and 65.2% in displacement ductility compared to the un-strengthened reference columns, and exhibited a more significant ductile failure charac-teristic. Moreover, the bearing capacity and displacement ductility of the confined columns were characterized by increasing with an increase in the number of textile layers and stirrup ratio, and a decrease in the concrete strength. The short fibers mixed in the strengthening layers also made a beneficial contribution to the bearing capacity and displacement ductility, particularly to the cracking load of the confined columns. Finally, a semi -empirical model was proposed to predict the axial stress and strain of concrete column specimens strength-ened with CTRC based on the experimental results and theoretical analysis. The results calculated by the pro-posed model were evidenced to be fundamentally consistent with the experimental results. Therefore, the proposed model in this study could effectively predict the stress-strain response of square RC columns confined with CTRC composites.