Impact of the Structural Defects on Risk Assessment of Concrete Bridges According to the Italian Guidelines 2020

The Italian infrastructure network of roads and bridges is one of the most complex in the world due to the territory orography. Italy is strongly interested in seismic and hydrogeological hazards, and, in addition, degradation and obsolescence phenomena are common in infrastructures nowadays approaching the end of their nominal life. Furthermore, these infrastructures are subjected to continuous traffic load increase over time. In 2020, the Italian Ministry of Infrastructure and Transport (MIT) published the guidelines for risk classification and management, safety assessment, and monitoring of existing bridges (LG2020) as an attempt to unify the multiple procedures of inspection, monitoring, and maintenance of infrastructures. The multilevel approach proposed in the Italian guidelines for the management of the complex existing system of bridges is herein discussed and investigated, focusing on an operational methodology to evaluate the impact of structural defects on the risk assessment. This study aims to develop an operational methodology for the application of the procedure generically depicted in the LG2020 for the attribution of the level of defectiveness based on the outcomes of the periodical inspections. In particular, such a methodology is applied to two of the most widespread bridge structural typologies in the Mediterranean area: reinforced concrete (RC) and prestressed RC (PRC) bridges. The defects’ extent and level to structural members are associated with the proposed procedure for different bridge risk ratings. The work presents a useful tool to proceed from the outcomes of the inspections to the assignment of a level of defectiveness for the bridge, which enters into the risk assessment. This is to drive decision-makers in the definition of future actions and interventions, such as the detailed assessment of safety level and relevant strengthening interventions or installation of continuous monitoring systems.