Evaluating the Mechanical Properties and Fracture Behavior of Welded-Wire Reinforcement Using Tension and Charpy Tests and Sub-Size Charpy Corrections

Abstract

Welded-wire reinforcement (WWR) is widely used as the main reinforcement in bridge decks and vertical shear reinforcement in concrete bridge girders. Past studies on concrete members reinforced with WWR have indicated that the reduced ductility of the cold-drawn wires leads to lower member ductility and rupture of shear reinforcing steel at failure. Additionally, the influence of the heat-affected zones created at the electric-resistance welds raises concerns regarding the mechanical behavior at the welded connections. To evaluate the fracture behavior of WWR meshes, an experimental program was developed involving tensile and Charpy V-notch (CVN) specimens sampled from straight bars and welded intersections. Due to size constraints, both full and sub-size CVN specimens were tested and a variety of size correction methods were trialed for degree of accuracy in comparing the two sizes of specimens tested. Tensile tests showed that the cross-welds decreased ultimate strain by an average of 10% without significantly altering yield stress, ultimate strength, or elongation at fracture. CVN tests indicated that the cross-weld tended to increase impact toughness by up to 30 J (22 ft-lbf) as the longitudinal and transverse bars became closer in size. Experimental values are evaluated using statistical methods, discussed, and compared to specification minimums in American and European standards.