PSI - Issue 84

L. Zoccolini et al. / Procedia Structural Integrity 84 (2026) 167–174

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The spans analyzed in this study are made of prefabricated reinforced concrete segments with a U-shaped cross section (Fig. 2). The deck was constructed using a span-by-span post-tensioning system, with the segments laid using an overhead gantry.

Fig. 2. A representative U-shaped segmental cross-section used in the analysed spans

Within this construction framework, the study examines different span structural types. The first configuration is represented by simply supported isostatic spans, characterized by a single-span static scheme with variable lengths from 26m to 36m and a planimetric pattern that can be straight, curved, or a transition between the two. In addition to these configurations, the case study also includes continuous beam spans, in which the deck extends in structural continuity over two or three consecutive spans, with lengths ranging from 44m to 72m. 4. Application of prioritization methods The two prioritization methods presented in CS465 are applied to the case study described in the previous section, using the 55 spans selected as a representative sample of the entire infrastructure. Each span is treated as an independent assessment unit, in line with the regulation, and analyzed for risk review and risk assessment to obtain the corresponding risk indicators. The methods are applied systematically and consistently across all spans considered, using a uniform set of input information, to allow a direct comparison between the results provided by the risk rating and the mean hazard risk level score. In particular, the analysis takes into account the construction and structural characteristics of the spans, the construction period, the span typologies and operating conditions, as well as the available information on the state of conservation. The form factor is defined according to the structural type of the span, distinguishing between simply supported isostatic spans and continuous beam spans developed over two, three, or four consecutive spans. In accordance with the provisions of CS465, isostatic spans made with prefabricated segments are considered to have a “very high” risk of brittle failure, as the loss of resistance capacity of a single element or post-tensioning system can lead to collapse with little possibility of redistributing the actions. On the contrary, continuous beam spans, thanks to their structural continuity and greater degree of redundancy, are classified by the regulations as having a “medium” risk of brittle failure, due to their greater ability to redistribute stresses and maintain a certain level of functionality even in the presence of localized damage. This distinction directly impacts the assignment of risk ratings and explicitly reflects the role of structural robustness in defining intervention priorities at the network level. The vulnerable details and materials factor is assumed to be constant across the entire studied sample, based on the available information and the construction characteristics. Specifically, the number of hazards related to 4.1. Risk rating approach The risk rating method is applied during the risk review phase, assigning each span scores based on CS465's scores for the various risk factors. Significant weight is given to the year of construction, which is the same for all spans and fell within the post-1996 range, reflecting the adoption of recent post-tensioning technologies and more advanced construction procedures than those used in older works.