FEM modelling of the Paderno d’Adda bridge (Italy, 1889)

The Paderno d’Adda bridge, also called San Michele bridge, is a marvellous arch iron bridge built in 1889 that allows to connect the two provinces of Lecco and Bergamo across the Adda river, between Paderno d’Adda and Calusco d’Adda. Despite its nearly 122 years of age, the bridge is still in service, allowing for alternated single-way transit of trains and vehicles. However, its present state of conservation seems rather poor and questions arise about its current health conditions. In light of this, an assessment of its present structural performance appears to be necessary. Towards this goal, the assembly of a complete FEM model of the bridge seems crucial for enquiring various aspects of mechanical response, specifically referring to both static and dynamic behaviours. Following recent previous work on this, with reference to conditions at the original design stage, the present paper attempts a first contribution to the modelling of the dynamic behaviour of the bridge, by investigating the different modal properties of the structure arising from the assembled FEM model.