Performance Evaluation of CFRP Confined Square and Circularised Reinforced Concrete Columns with Different Wrapping Schemes

Strengthening existing deficient reinforced concrete (RC) columns using fiber reinforced polymer (FRP) has been considered as an effective method to enhance the strength and ductility of RC columns. The increases in the strength and ductility of circular RC columns are much higher than the increases in the strength and ductility of square RC columns. Due to the popularity of square RC columns in practice, especially in the building structures, the behaviour of FRP wrapped square RC columns has been extensively studied in the literature. However, most of existing studies on FRP wrapped square RC columns investigated the confinement effectiveness of full FRP wrapping and a limited number of studies have focused on the confinement effectiveness of partial FRP wrapping and no study considered the confinement effectiveness of non-uniform wrapping. This study experimentally and analytically investigated the behaviour of square RC columns partially, fully and non-uniformly wrapped with CFRP under different loading conditions. The influence of the section circularisation on the confinement effectiveness of partial, full and non-uniform CFRP wrapping on the square RC columns was also investigated. Additionally, a strain model for partially FRP confined concrete was proposed in this study.