Report of recent advances in the development of welded reinforcement grid products and processes

Present day seismic design of concrete and masonry structures relies upon the ability of the confined concrete to absorb energy while being subjected to many cycles of stress reversals. Design engineers rely upon transverse reinforcement to properly confine the concrete (and/or grout) cores so that adequate inelastic deformations occur during an earthquake. Post earthquake investigations have shown that equally important to proper design is proper field installation of transverse reinforcement and placement of the core concrete around the longitudinal steel. This paper discusses a new proprietary Welded Reinforcement Grid (WRG) product, developed to replace conventional transverse reinforcement. The product is called BauMesh(R). Comparisons will be made of structural performance of this product as compared to conventional hoops, crossties and stirrups. Contractor reports of significant savings in material, labor, time and ease of concrete placement are discussed. A new manufacturing quality assurance protocol especially written for WRG, which will become a part of ASTM and ACI standards, is described. Recently developed computer controlled automated welding and testing procedures are discussed as they relate to ICBO approval of WRG. Comparison studies of material and labor cost, for recently completed conventional and WRG reinforced ductile concrete frames and shearwall buildings, are reported. Recent advances toward fully automated construction of concrete structures in seismic regions, using WRG technology, are reported, showing results of recently completed comparative time and motion studies performed by workers of concrete reinforcement subcontractors at their Southern California yards.