Analytical model of large-scale circular concrete columns confined by pre-stressed carbon fibre reinforced polymer composites under axial compression

In recent years, for the reinforcement of concrete structures, fibre-reinforced polymers have been extensively employed, thus enhancing the structural properties of the reinforced materials. This paper presents a pre-stressing strengthening method for the confinement of large-scale circular concrete columns. The axial compressive behaviour of confined columns was tested and analysed. The experimental and analytical results indicated that the stiffness, ductility, and bearing capacity of reinforced concrete (RC) columns strengthened with pre-stressed carbon fibre-reinforced polymer (CFRP) composites were significantly higher than those of non-prestressed columns. A theoretical relationship between the peak strength and bearing capacity of large-scale RC columns actively confined by pre-stressed CFRP composites was proposed. A tri-linear stress-strain model for the actively confined large-scale concrete columns was presented and compared with the experimental results. Moreover, the model is sufficiently simple for use in design. The results of the proposed model were compared with the experimental results of small-scale columns, and the influence of size was found to be critical to the analysis of RC columns confined by pre-stressed CFRP composites.