Reinforced Concrete Columns Confined by FRP Grids

Experimental investigation was carried out to verify the use of fiber reinforced polymer (FRP) grids as transverse reinforcement. The emphasis was placed on concrete confinement and seismic performance. Large-scale column specimens were tested under simulated seismic loading. The column reinforcement cages consisted of ordinary steel reinforcement as longitudinal bars and fiber reinforced polymer grids as transverse reinforcement. Grid spacing, grid pattern and the volumetric ratio of grid reinforcement, as well as the level of axial load were considered as test parameters. The results indicate improved deformability of columns when confined by properly designed grids. The grids provided easy cage assembly, savings in materials, and improved performance, while eliminating the congestion of column cage. Columns reinforced with fiber reinforced polymer grids developed at least 3% drift when current design practice was followed in terms of the amount and spacing of transverse reinforcement.