Axial Compressive Performance of Confined Concrete Columns Reinforced with FRP Grid Cage Stirrups

Fiber-reinforced polymer (FRP)-reinforced concrete columns have gained interest for use in corrosive environments due to their high tensile strength and corrosion resistance. This study aims to improve the compressive strength and deformability of FRP-reinforced concrete (FRP-RC) columns by investigating the mechanical behavior of FRP stirrups and longitudinal reinforcement. A mechanized FRP grid-cage confinement for concrete columns was advanced, and its axial compressive performance was experimentally evaluated. The results demonstrated that the FRP grid cage stirrups effectively limited concrete damage compared with glass FRP hoop-confined concrete specimens. Reducing stirrup spacing was found to be the most effective way to enhance the compressive behavior of FRP grid cage–confined concrete (FGCC). Furthermore, the effective confined area of FGCC was defined, and an existing model was modified. The updated axial load–strain model accurately predicted the compressive performance of FGCC.