Ductility of Concrete Members Reinforced with Welded Wire Reinforcement (WWR)

Past research studies have been conducted on the ductility of concrete members reinforced with welded wire reinforcement (WWR) and determined a new phenomenon called strain localization reduces member ductility due to superior bond between WWR and concrete. Such studies have concluded that strain localization adversely affects the ductility of members reinforced with WWR and it is unsafe to use WWR as tension reinforcement. In this study, 50 simply-supported, concrete slabs with a representative slab width of 2 ft (610 mm), thickness of 7 in. (180 nun), and total length of 21 ft (6.4 m) were tested to further examine the strain localization phenomenon on global deformations. Two major parameters were investigated, cross-weld spacing and wire diameter. The impact of these two parameters on strength, ductility, and mode of failure of concrete members reinforced with WWR was also studied. Moment curvature analysis was used to estimate inelastic deflections and ductility to investigate the effect of the reinforcement total elongation at failure of the wire material on the overall member ductility. It was observed that members reinforced with WWR with cross-weld spacing of 14 in. (355 mm) or more had similar ductility as members reinforced with loose wires (without cross-weld). Members reinforced with WWR with closely spaced cross-weld (i.e., 3 or 7 in. (75 or 180 mm)) showed erratic and often less ductility, however, the wire itself was shown to have low ductility. Failure of members reinforced with WWR provided sufficient warning prior to failure as evidenced by the ductility ratios in excess of 2.5. Additionally, a moment-curvature analysis based parametric study showed that an acceptable level of ductility can be achieved with a minimum total elongation of wire reinforcement of 3% at failure.