PSI - Issue 84

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

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The final risk rating is obtained by combining these scores into a dimensionless index for comparing different structures or configurations of the same structure. This approach provides an overview of the risk profile, which is particularly useful for preliminary screening and network-scale management. However, the highly aggregated nature of the method implies limited sensitivity to local conditions and specific degradation phenomena. 2.2. Mean hazard risk level scoring approach The mean hazard risk level score is based on a hazard-oriented approach, directly linked to the risk assessment results and inspection information. CS465 requires identifying all risks associated with post-tensioning systems, such as cable corrosion, loss of cable protection, or voids in post-tensioning ducts. For each identified risk, a likelihood level and a consequence level are assigned. The combination of these parameters allows the determination of a hazard risk level using the risk matrix shown in Fig. 1.

Fig. 1. Risk matrix, from (CS 465, 2020)

The mean hazard risk level score is determined by summing the individual hazard scores for each span. Each hazard risk level is assigned a hazard score that reflects the intensity of the identified hazard, ranging from 1 (for “negligible” hazards) to 6 (for “very high” hazards). The final mean hazard risk level score is calculated as the average hazard score for each identified hazard within each span, as defined in Eq. 2. = ∑ (2) Where is the individual hazard score, and is the total amount of identified hazards. 3. The case study The case study analyzed in this paper comprises a large post-tensioned concrete bridge, built between 2005 and 2009, which extends over more than 50 km. The infrastructure is predominantly developed in elevation. It represents a significant example of a continuous network-scale bridge. From a structural point of view, the bridge is a multi-span infrastructure, characterized by repetitive static schemes and geometric configurations. The extensive use of post-tensioning systems, adopted to ensure structural slenderness, continuity, and adequate static performance, makes the structure particularly representative of the issues addressed by CS 465 in terms of risk management and maintenance planning. The analysis in this paper is restricted to a subset of 55 spans, chosen as a representative sample of the full infrastructure, for clarity and compactness. To ensure that the outcomes are noteworthy in relation to the study's goals, a variety of structural types, deck lengths, and configurations are included in the selection.