PSI - Issue 84

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

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1. Introduction The structural safety of existing post-tensioned concrete bridges is now a matter of primary importance for infrastructure management. Indeed, many of these structures, built since the second half of the 20th century, are now characterized by the progressive aging of materials, potentially vulnerable construction details, and operating conditions that often differ from those considered during their design phase. In particular, the difficulty of directly inspecting the post-tensioning system and the potential for corrosion of active elements make it challenging to identify degradation mechanisms promptly and define intervention priorities. At the same time, management and maintenance are also crucial for recently constructed infrastructures. Although modern post-tensioning systems use more advanced materials, construction technologies, and design criteria, they continue to present specific challenges in terms of inspectability, durability, and long-term performance monitoring. For this kind of structure, early definition of management strategies and maintenance plans consistent with the expected risk profile is crucial to prevent premature deterioration, optimizing inspection activities, and ensuring adequate safety levels throughout the structure's life cycle. In this context, modern asset management strategies require objective and systematic tools to support decisions on inspection planning, maintenance scheduling, and the allocation of available resources. To this end, British Standard CS 465 (CS 465, 2020) proposes a structured approach to the management of post-tensioned concrete bridges, introducing risk-assessment methodologies to establish a hierarchy of intervention urgency based on uniform technical criteria. Indeed, the principles of risk review, risk assessment, and risk-based prioritization introduced by CS 465 have inspired multiphase approaches for special inspections, criteria for optimizing non-destructive investigations, and decision support methodologies applied to the management of post-test bridge networks (Bruschi et al., 2024; Mazzatura et al., 2023; Pettorruso et al., 2025). In particular, CS 465 defines two prioritization methods: one based on risk rating and another on the mean hazard risk level score. Both approaches are based on the results of risk review and assessment, but differ in terms of formulation, level of information aggregation, and sensitivity to input parameters. The first approach combines several weighted factors related to both the construction characteristics and the structure's context and condition, yielding a normalized overall risk index. The second approach, on the other hand, is based on the average severity assessment of the identified hazards, derived from a combination of the probability of occurrence and the associated consequences. Despite the growing adoption of these tools in professional practice, there is still limited literature that analyzes their robustness and behavior as input parameters vary. In particular, the question remains open as to how each method responds to different risk profiles and to what extent methodological choices can influence management and maintenance decisions. Using a sample case study, this study assesses the robustness of the two prioritization approaches from CS 465. The CS 465 standard is explained in Section 2, with special focus on the two suggested approaches. A multi-span bridge is described in Section 3. In Section 4, a realistic, large-scale management scenario is simulated by applying the two prioritizing methodologies to the case study. The study evaluates the two methods' sensitivity and identifies their advantages and practical drawbacks. Finally, section 5 concludes by summarizing the work's key findings and discussing how they may affect infrastructure maintenance planning and management. 2. Prioritization methods proposed by the CS465 The standard CS 465, “Management of post-tensioned concrete bridges,” is developed by the United Kingdom National Highways company as part of the Design Manual for Roads and Bridges. The primary purpose of CS 465 is to provide a structured methodological framework for managing the risk associated with post-tensioned concrete bridges, with particular reference to existing and recently constructed structures. The standard arose from the need to move beyond purely prescriptive or assessment-based approaches, introducing objective, repeatable criteria to support decisions on special inspections, intervention planning, and resource allocation. In particular, CS 465 is not intended as a structural verification code, but rather as an asset management tool geared towards risk assessment and management. It defines procedures for the risk review and risk assessment of post-