Structural performance of FRP confined seawater concrete columns under chloride environment

To alleviate resource shortage and environmental problems, a combination of fiber reinforced polymer (FRP) and seawater concrete is an attractive option for replacing conventional reinforced concrete in marine structures. The chloride ions in concrete structures increase with extension of service time due to penetration from the marine environment, resulting in serious deterioration of concrete structures. In order to apply such a material combination to civil infrastructure safely, the performance of FRP confined concrete with different chloride concentrations has been experimentally studied. The results show that a 23% reduction in strength is observed in 1-ply FRP confined concrete column when chloride ion concentration increases from 0% to 1.57% (saturated water level). Furthermore, a design-oriented model is proposed to evaluate the stress-strain behavior of FRP confined seawater concrete, as well as concrete with elevated chloride concentrations due to prolonged service time in the marine environment. The experimental findings and the proposed design-oriented model can promote the wide usage of FRP confined seawater concrete in offshore structures and artificial islands.