The effect of temperature actions on single‐sided fillet welds in small‐sized box girders of bridges

The use of small‐sized box girders has shown to bring numerous benefits in the design of bridges with short to medium spans. Therefore, it has become an established construction method in Germany. However, the beams are not accessible for inspection due to their small size, requiring the girder to be welded airtight. The limited accessibility also has consequences on the manufacturing process. Two of the four longitudinal fillet welds can only be executed from outside resulting in single‐sided fillet welds. As a result of the airtight construction, temperature actions lead to fluctuation of the internal pressure of the box. The single‐sided fillet welds are consequently subjected to unscheduled bending stress, which has an unclear impact on the weld. Subject of the research project, presented in this paper, is the influence of this unscheduled load case on the load‐bearing capacity of the girder. To quantify the temperature which leads to changes of the internal pressure, numerical studies based on meteorological data are performed. The load‐bearing behavior of single‐sided fillet welds is investigated in experiments. It can be shown that the load‐bearing capacity is underestimated by simplified calculation methods.