Investigation on the Performance of Non-uniformly, Discretely and Continuously CFRP Confined Square Reinforced Concrete Columns under Concentric and Eccentric loads

The behaviour of non-uniformly, discretely and continuously CFRP confined square reinforced concrete (RC) columns under concentric and 25 mm eccentric axial loads was investigated in this study. Eight square RC columns with a height of 800 mm and a side length of 150 mm were cast and tested. Two columns were reference RC specimens, two columns were non-uniformly confined with CFRP rings, two columns were discretely confined with three plies of CFRP rings and two columns were continuously confined with three plies of CFRP. The experimental results showed that non-uniform and continuous CFRP confinement significantly increased the load-carrying capacity and ductility of the square RC columns while discrete CFRP confinement resulted in a considerable enhancement of the load-carrying capacity and a significant improvement in the ductility. The improvement in the load-carrying capacity of the square RC columns due to non-uniform CFRP confinement was less than that due to continuous CFRP confinement but larger than that due to discrete CFRP confinement. However, the improvement in the ductility of the square RC specimens due to non-uniform CFRP confinement was larger than that due to discrete and continuous CFRP confinement under concentric axial load. It was also revealed that the brittle failure of CFRP confined square RC columns could be avoided by the application of non-uniform CFRP confinement.