Compressive behavior degradation of FRP-confined RC columns exposed to a chlorine environment

Abstract

Fiber-reinforced polymer (FRP) has been recognized as a promising method for strengthening reinforced concrete (RC) structures under a chlorine environment; however, it cannot prevent steel reinforcements from chloride-induced corrosion. Thus, the main objectives of this study were to (1) investigate the corrosion-induced performance degradation in FRP-confined RC columns under axial compression; (2) quantity the reduction of FRP rupture strain in FRP-confined RC columns subjected to a chlorine environment; and (3) propose a formula to estimate the load carrying capacity of FRP-confined RC columns considering the corrosion ratio. Twenty-eight columns with different FRP types (carbon fibre reinforced polymer (CFRP) and glass fibre reinforced polymer (GFRP)) and different layers of FRP (0, 1, 2, and 3) were conditioned under an accelerated corrosion process to obtain various corrosion ratios (0%, 5%, 10%, and 20%) and then tested under axial compression. The results showed that steel corrosion degraded the compressive response of FRP-confined RC columns, especially their deformation capacity. GFRP-confined RC columns generally had a better deformation capacity and were less vulnerable to steel corrosion than were CFRP-confined RC columns. Based on these test results, predictive equations for estimating the rupture strain of FRP were proposed as a function of corrosion ratio, which was introduced to modify an existing strength model of concrete confined with both FRP and steel stirrups. Finally, the ultimate load of FRP-confined RC columns with or without corrosion was predicted based on the modified concrete strength model.