In the last decade, the Italian bridge heritage, mostly made of ordinary or pre-stressed reinforced concrete structures, has increasingly shown signs of ageing, testified by the recent collapses as consequences of concurrent lack of maintenance, degradation of materials, increase in vehicular traffic and exceptional actions (e.g. due to landslides and floods). The recent Guidelines for classification and risk management of existing bridges confirm the large interest at policy-making level for accurate assessment of the in-service infrastructural heritage. In this context, the use of nonlinear analysis methodologies, which are already envisaged under appropriate safety formats for new structures, potentially represent an interesting alternative to ordinary safety evaluations to reduce uncertainty and over-conservativeness in the prediction.

In this paper, the application of the safety formats and analysis methodologies as those proposed by Eurocode 2 (UNI EN 1992-2) is critically reviewed in light of the specific aspects of existing reinforced concrete bridges. In particular, the definition of the design material properties and constitutive relationships is investigated in relation to the actual level of knowledge about the current state of the structure and the conditions of use. Furthermore, estimation of modelling uncertainty is proposed as a means to define some acceptance criteria for the specific numerical solution strategy to be used, following the most recent international research outputs. Finally, the relationship between the predictions provided by nonlinear analysis and those obtained by linear methodologies at different levels of detail is comparatively investigated with reference to a specific case study.