Principal tensile stress criterion for the shear assessment of existing concrete bridges

The structural assessment of existing road bridges that has been recently performed on the basis of the equally named provisions, issued in 2011 by the Federal Ministry of Transport and Urban Affairs, have revealed significant deficits in shear and torsion as well as fatigue resistance especially in prestressed concrete bridges. In a research project, funded by the Federal Highway Research Institute of Germany, design methods have been developed that were incorporated into the first addendum of the Structural Assessment Provisions. This paper describes the respective design methods for shear under static and cyclic loading without shear reinforcement. The procedures take into account current research results as well as the design codes for concrete bridges and are based on a verification of the principal tensile stresses. The use of the procedure and the main results are shown exemplarily by a design example of a typical box girder bridge of the German road network.