Fully bio-based-composite footbridge : strain monitoring during use phase

Last year a bio based pedestrian bridge, first in its kind, has been installed at the TU/e University campus in Eindhoven. Material test formed the basis for the innovative design and the research project resulted in the production and installation of the bridge. Because there are still a lot of unknowns in the material behaviour of the used bio-composites, it was decided to monitor and test the bridge further after production. For this purpose optical FBG sensors have been installed. The FBG sensors show the material strains in good detail and the results of the thus measured strains in load tests are shown. The test results are compared with results from earlier material tests. The short term structural behaviour follows closely the used elastic models based on calculated as well as measured stiffnesses. The long term time dependent behaviour however shows a number of different influences from creep, temperature and moisture content that can not yet be fully explained by earlier measurements and tests.