PSI - Issue 64

F.-B. Cartiaux et al. / Procedia Structural Integrity 64 (2024) 285–292 Cartiaux / Structural Integrity Procedia 00 (2019) 000 – 000

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1. Introduction Ageing transportation infrastructures have become a stringent concern in developed countries, and among them prestressed concrete bridges often appear critical. Indeed, their structural safety relies on the good state of the prestressing elements like tendons, which can be subject to prestress losses and loss of material due to corrosion. In addition, such structures are facing both a strongly increasing traffic and sometimes harsher environmental events due to the climate change, for which they were not designed initially. Thus, the efficient maintenance of prestressed concrete bridges deserves comprehensive monitoring means, to release a relevant and frequently updated knowledge of their structural state. Structural Health Monitoring (SHM) with continuous on-site measurements can contribute to this knowledge (Cartiaux et al., 2023a). However, it remains challenging to establish the link between raw measurements and clear synthetic indices, easily understandable and useful for the operational maintenance. A proposal for this simple health index has been documented in the case of the Mont-Blanc tunnel (Cartiaux et al., 2023b), but it may not be directly applicable on prestressed concrete bridges. This contribution presents the first steps of an ongoing case study which addresses this challenge in the case of a large undamaged prestressed concrete viaduct in France. Strain, vibration, and acoustic emission measurements have been gathered for more than two years, to build a database which is used by several research actions with the aim of giving a reliable and synthetic index of the health of the bridge from large volumes of SHM data. 2. Description of the Jules Verne viaduct The Jules Verne viaduct is located in Camon, near Amiens in northern France. It spans the river Somme with a double continuous box girder deck of 943 m length (Fig. 1). The two parallel prestressed concrete decks are independent and were built at different times, the upstream one in 1988 and the downstream one in 2002. Despite of a similar geometry and same length for their 19 spans, they show significant differences in their cross-section and in the prestress design. The deck structure is in a good state for both parallel decks, without any specific issue like cracks or other damages. Thus, the viaduct has been chosen as a case study for applying preventive SHM techniques on an undamaged structure yet undergoing its normal ageing process. It is also interesting to compare results on two similar decks with 14 years age difference. The aim of the study involving OSMOS Group, the Gustave Eiffel University, the CEREMA and the University of Le Mans is to gather as much valuable SHM data as possible to use it eventually in the design of health indices, which could be applied more generally to undamaged concrete bridges in the frame of preventive maintenance.

Fig. 1. The Jules Verne viaduct.