Ambient vibration measurements of steel truss bridges

Dynamic measurements of two steel truss bridges for Structural Health Monitoring (SHM) were performed. The investigated bridges were: a single supported one span truss bridge and a multi-span truss bridge. Two possibilities of measuring setup were considered. A simple arrangement made up of one polygon has been used for data acquisition of the single span truss bridge. A more complex measuring setup made up of two polygons with up to 32 channels has been used for the large bridge with an entire length reaching up to 500 m. A connection of both measuring polygons was achieved by Wi-Fi antennas. The reason why the multi-span truss bridge was chosen for SHM is that the construction is nowadays overloaded. The dynamic measurements were done, ambient and semi-ambient data were analysed. After that, some mode-shapes were identified from the acquired data and then the data were compared with numerical calculations. Finally, experiences and conclusions from the ambient data measurement are summarized.