Confinement of reinforced concrete columns with welded reinforcement grids

Experimental research was conducted to investigate structural performance of reinforced concrete columns confined with welded grids. Ten full-scale columns with different volumetric ratios, spacing, and arrangement of welded reinforcement grids were tested under simulated seismic loading. The columns were subjected to constant axial compression accompanied by incrementally increasing lateral deformation reversals. Results indicate that welded reinforcement grids can be used effectively as confinement reinforcement, provided the steel used has sufficient ductility and the welding process employed does not alter the strength and elongation characteristics of steel. The grids improved the structural performance of columns, which developed lateral drift ratios in excess of three percent with the spacing and volumetric ratio of transverse reinforcement similar to those required by the ACI 318-95 Building Code. Drift capacity further increased when grids with larger number of cells were used. Furthermore, the use of grids reduced congestion of reinforcement while the dimensional accuracy provided effective support to longitudinal reinforcement.