Axial Compressive Behavior of Square-Section Concrete Columns Transversely Reinforced with FRP Grids

Using grid-type stirrups as transverse reinforcements in reinforced concrete (RC) columns can not only provide higher confinement of the concrete core but also lead to an improved concrete cover and better protection to longitudinal reinforcements when compared with conventional stirrups. Fiber-reinforced polymer (FRP) grids, which combine the advantages of grid-type stirrups and FRP composites, are viable for use as transverse reinforcement in square-section RC columns in corrosive environments. However, there were few researches addressing RC columns reinforced with FRP grids. To investigate the axial compressive behavior of RC columns transversely reinforced with FRP grids, experimental investigations were conducted on 17 short square-section columns in small scale (180 x 180 x 600 mm(3)). Columns were transversely reinforced by CFRP/BFRP grids, weld reinforcement grids (WRG), and steel hoops. The results indicate that although FRP grids could provide less confining pressure than WRG, their performance is better than that of conventional hoops. Finally, an analytical model for predicting the stress-strain behavior of concrete core reinforced with grid-type stirrups is proposed considering the arching action of the confined concrete core. The proposed model shows a good agreement with the present test results as well as those from the existing literature.