PSI - Issue 64

Antonio Bilotta et al. / Procedia Structural Integrity 64 (2024) 2109–2116 "Bilotta et al." / Structural Integrity Procedia 00 (2023) 000 – 000

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1. Introduction Structural health monitoring (SHM) systems are nowadays largely used as a screening methodology for both buildings and infrastructures. A SHM system led to extensive knowledge of the real behavior of a structural system, monitoring day-by-day changing in selected pivot parameters, while identifying possible both local or extensive damages causing by material degradation during time, as well as heavy structural internal actions generated by both environment and human activities (Ko and Ni., 2005). Many studies are available in the technical literature about the SHM systems for long-span bridges, giving an intricate frame of solutions strongly dependent on the type and extension of the structures (Schlune et al., 2009; Sun et al., 2017). Conversely, few applications and approaches are proposed to design a SHM system for medium-span bridges with girder decks. In fact, for this kind of bridges a general and simpler approach can be proposed even if it still necessary high accuracy in monitoring parameters. The medium-span bridges constitute a significant portion of urban roads in many countries, thus design procedures of SHM systems for such bridges is a key issue for management of many infrastructures (Xiang et al., 2023). The paper is aimed at showing a real-case implementation of SHM system with multiple objectives: (i) having a monitoring system that can be used for day-by-day assessing of the infrastructure health due to the (natural) degradation process; (ii) helping the managing system in scheduling relevant maintenance operations; (iii) using post-processing and remodulation data acquisition in order to identify traffic loads and its time variability along the infrastructure; (iv) characterizing pivot data from the acquisition to do model updating with refined Finite Element (FE) models, allowing to predict location and intensity of possible damages. After a brief introduction of the considered bridge structures, their geographical location and historical background of the structural design, the paper discusses main structural issues arose from periodic inspections, leading the design process in terms of type of sensor to be used and their localization. Then, a specific focus on the SHM system layout is discussed, along with some preliminary data arising from first acquisitions. The road system selected for these monitoring activities is composed by eight ramp viaducts which connect the Neapolitan local city roads near the port with the A3 Italian highway infrastructure. These bridges are strategic structures on which heavy traffic loads flow from several main highways of the Italian infrastructure system, nowadays. The design of all the viaducts began in the 1971, while the construction began in the 1973 and ended in the 1978. Figure 1 shows the plan view of the infrastructure system, starting on the left from the mentioned “Via Marittima”, nowadays known as “Via Marina”, an important part of the local city roads in Naples. The eight structures here discussed in terms of structural health monitoring activities belong to the part “A”, ”B” and “C” indicated into the figure. The bridge viaducts are characterized by simply supported decks also with half joints (Gerber connection), mostly realized with PC beams with spans among 20 m and 45 m. In some cases, steel beams were used instead of concrete structures. Since the overall layout fit into a complex urban system, the design of the bridges was largely dominated by urban constraints, thus resulting in different pier shapes and not conventional arrangements for elevation purpose (examples are shown in Figure 2). Many of these bridges were designed by Riccardo Morandi that was able to find the most efficient solutions. 2. Bridges structural layout 2.1. The infrastructure system

Figure 1 Overall plan of the infrastructure system (from Morandi 1980).