Bridge Structural Reliability for Maintenance Prioritization

A significant percentage of assets of the Italian national bridge stock have outlived their nominal design service lives, a situation that has led to an increasing number of structural failures over the years, e.g. the deadly 2018 collapse of Morandi Bridge in Genoa. It would have been impossible to replace all existing infrastructural assets, so the focus was shifted to their upkeep. This is commonly achieved through structural health assessments of bridges and through properly planned and prioritized maintenance interventions. For a proper management of their bridge stock, infrastructure managers need a prioritization tool capable of quickly assessing whether a particular unit is in immediate need of maintenance. Currently, the prioritization of each bridge inside a stock is often based on its structural reliability. Yet, whilst several complex and time-consuming structural reliability assessment methodologies exist, these often fail to be quick in application. The present article provides for this shortcoming by introducing a novel simplified structural reliability model. In particular, it provides a framework for the assessment of overload, degradation, seismic, hydraulic and landslide risk factors and a detailed formalization of the most widespread, i.e. overload and degradation. On the basis of such a swift model, infrastructure managers can quickly detect rapidly deteriorating bridges, guarantee well-timed interventions and improve infrastructure user safety.