PSI - Issue 62

R. Martini et al. / Procedia Structural Integrity 62 (2024) 392–399 Martini R. et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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Figure 1. Bridge case studies: (a) satellite view (Google Maps), (b) picture of the two paired bridges, (c) longitudinal profile and static scheme

The definition of the CoA has two main purposes: ( i ) to define the risk classification of existing bridges in a standard way all over Italy, and ( ii ) to obtain a unique rating tool to define urgent safety countermeasures and to prioritize maintenance works.. In Part I visual inspections on bridge site are required, as well as special inspections when necessary (e.g., in case of pre-stressed concrete bridges). Level 0, 1, and 2 for the bridges at hand were performed by 2 teams of engineers constituted by FABRE and ANAS personnel (collaborating each other), and a CoA was achieved. Special inspections, foreseen by the Guidelines 2022 for the pre-stressing system, were not done, but are expected to be executed shortly. Part II contains recommendations to perform a safety assessment of the bridge load bearing capacity (Level 3 and 4), following rules consistent with the Italian technical code (NTC2018). Guidelines introduces different performance level for the bridge (adequate, operative, and transitability conditions), and the concept of "reference time", namely the time frame to which the verification is conventionally referred, calibrating partial safety factors and loads in spirit of the limit states approach to perform the safety assessment for each level of performance. Operative and transitability conditions are characterized by a limited time frame, after which analyses have to be repeated or countermeasures must be taken to ensure the due level of safety usage (e.g., repair works or load restrictions). This part was addressed for the bridges at hand, and the main results are reported in Section 4. Part III contains suggestions for the monitoring activities during the bridge life cycle. In this part, recommendations about short-time and long-time monitoring are provided. Furthermore, suggestions of tests that can be done to assess the static and dynamic performance of a bridge are also provided. The bridges case study have been object of numerous surveillance activities during which both static and dynamic tests were performed. Moreover, a permanent static and dynamic monitoring system has been installed on the DB that, as discussed in the sequel, is still open to traffic. A summary of the performed activities on the bridges and their contextualization within the Italian Guidelines 2022 framework is reported in Figure 2. 3. Inspection activities and class of attention The bridges were visually inspected on February 2022. According to Guidelines 2022, all the structural members were inspected, including the pavement joints and accessories. The bridge decks were inspected by using the by bridge aerial platform, which allowed for a detailed inspection of girders and supports, while the substructures and foundations (where visible) health status were inspected by accessing under the bridge.