PSI - Issue 78

Gregory Santilli Di Luia et al. / Procedia Structural Integrity 78 (2026) 1513–1520

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1. Introduction Reinforced concrete bridges are a fundamental component of road infrastructure and their proper management is essential for ensuring the functional continuity of transportation and the resilience of the network, see Salvatore et al. (2024). However, many of these structures are currently subject to increasingly high-risk scenarios due to the combined effect of material aging and exposure to potentially destructive seismic events. One of the main long-term degradation mechanisms is the corrosion of the reinforcement bars, primarily caused by the penetration of chlorides or carbon dioxide through the concrete cover, especially in marine or industrial environments see Tuutti (1982). This phenomenon progressively reduces the effectiveness of the reinforcement (i.e., net cross-section, yield strength, ductility), compromising the load-bearing capacity, energy dissipation, as well as the overall performance of the structure see Biondini and Vergani (2012). At the same time, concrete undergoes a loss of stiffness, strength, and confinement, further amplifying the vulnerability of the system. From a seismic perspective, these effects impact on the dynamic behaviour of the bridge relevantly. In this context, accurate nonlinear numerical modelling of the entire bridge, including the time-dependent effects of corrosion, is crucial to estimate the seismic response under progressive degradation scenarios, to quantify the evolution of structural vulnerability over time, and to support strategies for maintenance, retrofitting, and prioritisation of interventions see Yang et al. (2025). In this context, the current paper aims to conduct the detailed vulnerability assessment of an existing bridge using a Finite Element (FE) model and taking into account the evident level of corrosion identified during the on-site inspection. To this end, the main characteristics of the bridge are described in Section 2, while the implementation of its numerical model is detailed in Section 3. Focusing on the simulation of various time-dependent corrosion scenarios, the modelling strategy and the scenarios investigated are outlined in Section 4. Finally, the main outcomes of the analyses are presented in Section 5, whereas the conclusions are provided in Section 6. 2. Case study description The viaduct under evaluation, shown in Figure 1, is part of the “S.S. 16 Adriatica”, a main road in the national route network. Built entirely in reinforced concrete between 1961 and 1980, the viaduct has a total length of 84 meters and a width of 13.50 meters. It features five spans: two end spans with a length of 15.40 m, and three intermediate spans of 17.55 m each. The roadway consists of a two-lane carriageway approximately 10.5 m wide, with a 1.50 m wide paved footpath equipped with safety barriers on both sides. The viaduct presents an isostatic structural scheme, due to the presence of Gerber saddles with internal hinges in spans 2 and 4. The piers consist of five rectangular-section shafts with cast-in-place stiffening crossbeams and vary in height from 6.90 m to 9.74 m. The abutments are monolithic, featuring a front wall and wing walls made of reinforced concrete. The bridge underwent extraordinary maintenance, during which some of the pier shafts were strengthened. However, analysis indicated that the seismic safety of the structure did not improve significantly as a result.

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Fig. 1. Investigated bridge: (a) schematic elevation; (b) detail of the deck structure.