PSI - Issue 78

Manuel Capogna et al. / Procedia Structural Integrity 78 (2026) 1064–1070

1066

For bridges, this lack of segmentation means that a simple single-span bridge and a multi-span viaduct, potentially subject to diverse environmental and structural conditions across its segments, receive the same level of descriptive granularity. Such an approach often yields an averaged attention value that may fail to highlight critical local vulnerabilities, such as specific piers exposed to heterogeneous geohydrological risks (e.g., partially immersed in riverbeds or located in landslide-prone areas). This simplification can lead to misprioritization of maintenance efforts and a suboptimal allocation of resources. To address these limitations, Ansfisa (Renzi et al., 2023) and several authors have proposed specific prioritization indices for bridge maintenance (Calò et al., 2024; Floridia et al., 2024; Principi et al., 2025). 3. Proposed segment-based classification methodology To address the limitations of the current single-value attention class for bridges, this paper proposes adapting the segment-based risk classification methodology from tunnel guidelines to bridge assessment. This extended methodology enables a more detailed evaluation of attention classes across different structural segments of a bridge, moving beyond a monolithic assessment. The core idea is to divide a bridge into sections—referred to as 'segments' (or conci, in the terminology of Italian guidelines)—defined as “homogeneous portions of the structure, even of limited length, characterized by similar structural and geometric features, operating conditions, and exposure to hazards” (Italy, 2020). This segmentation enables independent risk assessments for each segment, accounting for local material degradation, specific structural configurations, and differentiated hazard profiles. The proposed approach integrates a multi-hazard analysis framework, considering risks such as seismic, hydraulic, and landslide hazards, which often vary along the length of a bridge, especially for long viaducts. For each segment, parameters influencing seismic hazard, vulnerability, and exposure are evaluated. Seismic vulnerability, for instance, is intrinsically linked to structural characteristics such as static configuration, span length, and materials used. Similarly, hydraulic and landslide risks can significantly differ for individual piers or spans depending on their specific location within a riverbed or a geological area. The model calculates an attention class for each segment based on the combination of these risk factors and a diffusion index table. A practical evaluation of this methodology has been conducted through custom-programmed Microsoft Excel spreadsheets, using as examples the ‘Viadotto Italia’ on the Lao river in Italy (on the A3 Highway) and road and railway bridges over the Paraná de las Palmas and Paraná Guazú rivers in Argentina. The first viaduct, for which the simulation was performed, is located in northern Calabria – bordering Basilicata – in the municipalities of Laino Borgo and Laino Castello, in the province of Cosenza. In 1964, it was the subject of a competition won by Carlo Cestelli Guidi, Fabrizio de Miranda, and Carmelo Pellegrino Gallo.

Fig. 2. (a) ‘Viadotto Italia’ on the Lao river - Intermediate cross-section of the deck; (b) Longitudinal profile of the steel spans - phases and times of realization