The rescue of small rolled beams embedded in concrete bridge in Germany

Iron sections embedded in concrete have been known from the beginning of the nineteenth century. This technology has been widely applied ever since and has proven to be a reliable technique for bridges with small spans. Nevertheless, the consideration of the bond between steel and concrete and the transverse load distribution of such structures has remained a broadly discussed topic among engineers. Demolition of a small German road bridge constructed in 1949 with this method was looming, as a conventional reassessment failed to provide the required load-bearing capacity. In an effort to save this historic bridge, the actual structural behaviour of the bridge was investigated by in situ testing. Displacement transducers and strain gauges mounted on selected steel beams recorded the behaviour during the application of static as well as travelling loads. Based on these results, the model for the transversal load distribution could be revised; thus, the bridge fulfilled the requirements after all.