PSI - Issue 78

Giuseppe Santarsiero et al. / Procedia Structural Integrity 78 (2026) 560–567

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1. Introduction Bridges represent a strategic component of the national transportation infrastructure. In Italy, a large portion of the bridge stock was built during the post-war period, especially between the 1960s and 1980s, using prestressed reinforced concrete technologies. Among these, post-tensioned systems have been widely adopted due to their efficiency in spanning medium to long distances and their reduced construction time. However, these systems are also vulnerable to specific degradation mechanisms, particularly in the presence of construction defects and inadequate maintenance practices and may need urgent interventions to mitigate structural risk (Santarsiero et al. 2023). Recent collapses and critical failures, often occurring without prior visible signs of degradation, have increased the awareness of the fragility of this infrastructure class. In this context, the Italian Guidelines for bridge assessment (MIT 2020) require the execution of regular Level 1 inspections, aimed at detecting visible defects and assigning a Class of Attention (CoA) based on observed conditions. Despite their visual nature, Level 1 inspections generate a large amount of information, especially when digitised and aggregated. This paper leverages such data to perform a systematic analysis of degradation phenomena affecting post-tensioned prestressed concrete beams in a homogeneous set of bridges managed by the same authority in the Basilicata region. All the analysed bridges share common features: year of construction (around 1970), structural scheme (simply supported beams), and presence of post-tensioned cables, which represent failure critical elements. For this reason, depending on the nature and extent of degradation, post-tensioned RC beams may need interventions that can be made through several techniques, such as steel plates (Ayek et al. 2013), CFRP unbonded elements (Chen et al. 2024) or external steel tendons (Santarsiero et al. 2024).

Fig. 1. Inspection form for prestresses reinforced concrete beams.

Within this framework, the main goals of this study are: • to compute a degradation index (IDeg) for each beam based on defect severity, extent, and intensity, using the defects reported in the inspection form for prestressed reinforced concrete beams (Fig. 1); • to compare internal and edge beams within each bridge to highlight differential exposure to aggressive agents; • to provide a prioritisation of bridges for further inspections, maintenance actions or interventions, similarly to other studies (Rossi et al. 2023).