Static and dynamic evaluation of continuity effect of corbels in timber bridges

This paper presents part of the ongoing experimental and analytical work to investigate the effect of corbels on continuity in timber bridges. Full scale beams with corbels were erected for testing the extreme boundary conditions such as simply supported and fixed end conditions. The states of continuity in the test beams were assessed through a three span beam loading test set up. Dynamic tests were performed on the test beams and the modal parameters extracted were compared against those obtained for simply supported beams without corbel. Analytical investigations were conducted and then compared with the experimental results. The static experimental results obtained showed changes in the vertical displacement for different boundary conditions. The magnitude of reduction in the measured vertical displacement was fairly sensitive to the change of boundary conditions. Hence, changes in vertical displacement at mid-span can be used as an indicator for different boundary conditions, which relate to the effect of corbel on both continuity and effective span length in a structural system, especially for timber bridges. A comparative analysis of the first natural frequency for each boundary condition was then undertaken with reference to a simply supported benchmark. The analysis confirmed that the effects of changes in the boundary can be detected using modal parameters.