Evaluation of fragility curves of a reinforced concrete viaduct in Central Italy: a preliminary analysis

Recent seismic events occurred in Central Italy drew the attention towards the resilience of the Italian road network, which is characterised by a significant number of old reinforced concrete bridges and viaducts. In this context, the fragility assessment of existing bridges is crucial, since their collapse or loss in functionality after earthquakes may lead to significant economic and social consequences. As a preliminary study oriented to characterizing the fragility level of the Italian bridge heritage, this work focuses on the real case study of the Chiaravalle viaduct, located in Centre Italy, which may be representative of a widespread class of reinforced concrete bridges in Italy. The viaduct is entirely characterized by a reinforced concrete structure, with a link continuous slab on simply supported V-shaped girders. After a preliminary study on the current structural health of the bridge, a numerical model is developed in order to capture the failure mechanisms most likely to occur. Fragility curves, built by accounting for all the relevant demand parameters and limit states, provide useful insights about the main structural deficiencies of the system at hand.