Effect of Manufacturing Imperfections on the Service-Level Performance of Elastomeric Bridge Bearings

During the vulcanization process of steel-laminated elastomeric bridge bearings, unavoidable flow of elastomer occurs inside the mold under high pressure and nonuniform heating. This may cause the interior steel laminates to misalign or distort in the finished bearing. There has been limited research to understand and quantify the effects of manufacturing imperfections, such as vertically shifted, rotated, and bent steel laminates, on the mechanical behavior of elastomeric bearings. This paper presents a finite element investigation on the effects of manufacturing imperfections on the performance of elastomeric bridge bearings subjected to service-level loads. It is observed that such imperfections have a negligible effect on the maximum shear strain induced in the elastomer. The strain hardening behavior of the elastomer under relatively large shear strains limits the maximum shear strains to values lower than those predicted by the pressure solution. In one cycle of loading, the vertical deflection of bearings is affected slightly by these imperfections. However, manufacturing imperfections can increase the tensile stresses in the steel laminates causing plastic damage. The spread of plastic damage in the steel laminates with repeated cycling may affect the long-term performance of the bearings.