ABSTRACT
The identification of the global characteristics of an ancient iron railway bridge was carried out. This railway bridge was built in 1896 and is still in service on the Avellino-Rocchetta-Foggia line in South Italy. At first some dynamic tests were performed using input excitations generated both by the train transit and by a mechanical vibrator. The output signals were recorded through transducers. Then the results of field tests were used to define predictive models, as well as, to validate and to update finite element models of the structure. In particular the use of a monitoring technique led to assess the dynamic characteristics (natural frequencies and mode shapes). The knowledge of the identified modal characteristics allowed to validate and to optimize the finite element model (FEM) of the bridge. Finally, the optimized model of the bridge was used to assess the dynamic response of the bridge under the transit of trains and under earthquake ground motions. In particular dynamic amplification factors and maximum acceleration responses were evaluated for different load conditions.
