Dynamic methods for health monitoring and structural identification of bridges

Dynamic methods are a useful tool in bridge engineering. Their purpose is twofold. First, they provide guidance on the validation of a mathematical model of the structure under investigation. Second, repeated tests over time can indicate the effect of structural modifications due, for example, to the occurrence of possible damage or to the restoration works carried out on the bridge. Recent technological progress has gen-erated accurate and reliable experimental methods, enabling a good estimate of dynamic behavior of a struc-tural system. Although experimental techniques are now well-established, the interpretation of measurements still lags somewhat behind. This particularly concerns structural identification due to its nature of inverse problem in vibration. In addition, when identification techniques are applied to the study of real-world bridg-es, additional obstacles arise given the complexity of the structural behavior, the inaccuracy of the analytical models used to interpret experiments, measurement errors, and incomplete field data. This study discusses some of these aspects with reference to a series of output-only vibration tests carried out on a new curved multi-span viaduct and on a class of existing twin arches bridges.