In-situ shear tests on a 64-year-old road bridge

In the summer of 2017, unique field studies regarding the shear capacity of existing bridges were conducted by the Chair of Concrete and Masonry Structures of Technical University of Munich (TUM). In total, five load-to-failure tests took place at a 64-year-old, 163.0 m long pre-stressed concrete bridge in the town of Hammelburg in Bavaria. The continuous road bridge over the Franconian Saale river was chosen because of the relatively large number (seven) of bridge spans and the small amount of shear reinforcement (less than 36.5% of the present minimum according to Eurocode 2) which is typical for this construction period. The primary objective of the field test was to determine the shear capacity of existing bridges with a construction time before 1966 (year of implementation of minimum shear reinforcement in German standards). The five full-scale in-situ tests were carried out in different bridge spans and at the area of the inner supports (near the points of zero moments). The test loads were short-circuited, via a 31.65 long box girder made of steel, into the supporting points of the examined bridge span. The intended behaviour - a shear force failure of the main girder with corresponding oblique shear cracks - was achieved in all five experimental tests.