PSI - Issue 44

Emanuele Renzi et al. / Procedia Structural Integrity 44 (2023) 737–744 Emanuele Renzi et al./Structural Integrity Procedia 00 (2022) 000–000

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1. Introduction The Italian heritage of road and highway bridges is outdated; mainly it consists of structures dating back to the second half of the last century that are therefore approaching the end of their useful life (Pregnolato, 2019), made with common types and construction technologies, which begin to show similar signs of degradation and for which it is legitimate to expect a loss of functionality in the same time frame, conceivable in the not distant future (Jeong et al., 2016, Kreisa et al.,2016). Most of the bridges built in Italy not only begins to age, but was designed according to outdated standards, calibrated on different traffic demands and loads, and often conceived in the absence of both anti-seismic criteria and a design culture sensitive to aggressive environmental conditions, durability and sustainability (Jančula et al.,2021). Therefore, in order to maintain an adequate level of efficiency of the road infrastructures, numerous and frequent maintenance interventions are necessary to avoid more important rehabilitation works. In fact, the presence of numerous road works sites causes significant changes to the road safety and traffic flow regularity. The long queues of cars and the numerous changes in speed and lanes reduce the safety margins for both motorists and workers (Debnat et al.,2014, Shema et al, 2022). This is certainly more evident after the recent collapse of the Polcevera viaduct in Genoa in 2018, which diverted motorway traffic to the urban road network with inevitable and numerous traffic jams (Malerba, 2022, Bazzucchi et al., 2018, Calvi et al., 2018). Therefore, the assessments on bridges must be carried out with the help of an appropriate BMS structured in order to take into account all types of risks in the assessment. The Italian bridges are managed by numerous entities, ranging from the local dimension of small municipalities to large motorway and railway infrastructure managers using proprietary BMS. At the local level, the BMS are primarily conceived for the management and updating of the bridge archive, for the registration of the inspection activities carried out, for the planning of interventions and for the allocation of funds (Fattorini et al. 2022, Bortot et al.,2006, Zonta et al. 2007, Yue,2013). Many of the current BMS, when present, carry out assessments in relation to the conditions of the bridge and do not consider external factors such as seismic, hydraulic and landslide risk. In the Italian legislative framework, the regulatory interventions on the maintenance of road bridges began with the circular on the “Control of the stability conditions of roadworks” no. 6736 / 61A1 (MPW, 1967), to continue with various regulations, including “Instructions on planning road maintenance, bridges and viaducts” (CNR, 1993). The current provisions of the technical standards for constructions (MIT,2018) regarding existing structures are focused on buildings, while the comment (CSLLPP,2019) gives only indications about seismic actions on existing bridges, however without indications on the assessment under service loads. Similarly, the current Eurocode 8 – Part 2 (EN 1998-2:2005) provide rules for newly constructed bridges, while Eurocode 8 – Part 3 (EN 1998-3:2005) provide only deals with existing buildings, although the Eurocodes second generation is planned to cover at least assessment, re-use and retrofitting of existing structures and includes existing bridges. Therefore, in order to fill a regulatory gap and standardize the assessment of existing bridges, the Superior Council of Public Works has issued the guidelines for risk classification and management, safety assessment and monitoring of existing bridges (CSLLPP,2020) which have been approved as a technical code (MIMS,2020). With the issue of the Italian Bridges Guidelines a new multilevel approach was introduced and numerous experiences have been successfully carried out (De Matteis et al., 2022, Buratti et al., 2022a, Buratti et al. 2022b Santarsiero, 2021, Manarin et al.,2022). The gradual transition to bridge guidelines by road and motorway concessionaires highlighted the need for interpretative clarifications, in order to avoid excessive discretion which often resulted in overly conservative assumptions. For the reason highlighted above and in the exercise of its regulatory autonomy, Ansfisa with the collaboration of the Fabre Consortium has developed the Operating Instructions for the application of the Bridge Guidelines that will be examined in depth in this work.

Nomenclature BMS

Bridge Management System Ministry of Public Works

MPW