WELDED WIRE SHEAR REINFORCEMENT FOR PRESTRESSED CONCRETE BRIDGE GIRDERS

Abstract

Welded wire reinforcement (WWR) is a steel product that is prefabricated into welded sheets. While this product is seeing use as shear reinforcement in precast concrete bridge girders for some states, other states, such as Alabama, do not permit its use. The main concern is the ability of the wires to perform due to their higher yield strength and the presence of welds reducing their ductility. The perceived benefit is much faster placing times that is innate in placing sheets over single bars, leading to savings in labor. The primary focus of this study is to assess the viability of using WWR as shear reinforcement including determining the best practices and challenges regarding its use. This was achieved by performing a literature review on the material properties of WWR, on its ability as shear reinforcement in concrete, and on the best design practices surrounding the manufacture of the product. In addition, an interview was conducted to determine the constructability of WWR, and designs of typical Alabama Department of Transportation (ALDOT) girders were performed to identify design-based limitations or benefits that caused by ALDOT specifications. Finally, a survey was performed to determine the current state of practice of WWR among state departments of transportation and to register the potential interest in WWR’s use as shear reinforcement. Overall WWR appears to be acceptable for use as shear reinforcement in prestressed concrete bridge girders. While WWR does suffer from a reduction in ductility compared to typical reinforcing bars, WWR reached shear capacities and controlled cracking as well as traditional reinforcing bars. WWR does show weakness to cyclic loading, but this fatigue weakness due to welds is considered negligible if the welds are placed outside the high stress region. The benefits of WWR appear to mainly fall in its constructability, with the product greatly reducing the number of installed stirrup elements in the fabrication bed, resulting in faster placement and inspection. The removal of stirrup hooks with its cross-wires acting as anchorage further aids this process.