Full-scale shear capacity testing of an existing prestressed concrete bridge

Due to the relatively high average age of the existing bridges, a dramatic increase both in traffic volume and axle loads and because of modified design standards, a realistic prediction of the shear capacity of existing prestressed concrete bridges with little shear reinforcement has become an important topic in German research. In 2017, the Chair of Concrete and Masonry Structures of the Technical University of Munich (TUM), supported by the Federal Ministry of Transport and Digital Infrastructure, was given the unique opportunity to conduct full-scale field tests at the Hammelburg Bridge built in 1955. According to systematic strength evaluations, many concrete bridges in Germany, especially those which were built prior to 1966, show severe (theoretical) deficits regarding longitudinal shear capacity. The results of the strength evaluation can often not be verified in the real bridges though. The primary objective of the field test therefore was to determine the actual shear capacity of existing prestressed bridges aiming at closing the gap between structural analyses and experience in regard to older concrete bridges. The article at hand presents the conceptual approach, the test set-up and the execution of the in-situ testing, the used measuring equipment and essential findings gained from the conducted full-scale experiments. Furthermore, the results are discussed and the measured maximum loads of all five tests are compared to the results of different theoretical approaches and engineering models, respectively.