Behavior of FRP-Confined Circular RC Columns under Eccentric Compression

Strengthening of reinforced concrete (RC) columns through lateral confinement with a fiber-reinforced polymer (FRP) jacket has become an increasingly popular technique over the last two decades. To enable the safe and reliable design of such FRP jackets, extensive research has been conducted on the behavior of FRP-confined concrete columns. Most of the existing research, however, has been focused on FRP-confined concrete columns under concentric axial compression, so the current understanding of the behavior of FRP-confined RC columns under eccentric loading is inadequate. This paper presents the results of an experimental study involving 10 FRP-confined circular RC columns with a diameter of 300 mm under eccentric compression. The variables included the FRP jacket thickness, the initial load eccentricity, and the column slenderness. The test results show that FRP confinement is effective in enhancing both the ultimate load and the ductility of circular RC columns under eccentric loading, and the load eccentricity and the column slenderness have important effects on the column behavior. Finally, the design equations in the Chinese national standard and the UK Concrete Society design guidance for the ultimate axial load of eccentrically loaded slender FRP-confined RC columns are evaluated by comparing their predictions with the test results. It is found that the design equations in both the Chinese national standard and the UK design guidance predict the test results well, with the latter providing slightly more conservative predictions.