PSI - Issue 78

Carlo Pettorruso et al. / Procedia Structural Integrity 78 (2026) 1190–1196

1193

The flexibility of the WSM lies in the ability to assign custom weights to each evaluation category. Three standard scenarios are proposed: • Accuracy-driven, ideal for precise diagnostics on critical or deteriorated structures; • Cost-driven, suited for large-scale inspections where budget optimization is essential; • Impact-driven, used in high-traffic environments where minimizing disruption is a priority. The weights of each scenario are reported in Table 1. In each case, the most relevant category is assigned a dominant weight (e.g., 0.6), while less critical aspects receive proportionally lower values. If a factor is deemed irrelevant (e.g., no traffic interference), it can be excluded by assigning it to a weight of zero.

Table 1 Proposed scenarios

Accuracy-Driven Scenario

Impact-Driven Scenario

category

Cost-Driven Scenario

weight factor

Accuracy

0.60

0.20

0.20

w 1

Ease of Use Traffic Impact

0.15

0.10

0.10

w 2

0.15

0.10

0.60

w 3

Cost

0.10

0.60

0.10

w 4

This structured, scenario-based approach ensures that the ranking of NDT methods is both quantitative and adaptable, supporting decision-makers in selecting the most suitable technique for different bridge inspection contexts. 4. Practical application of the framework The methodology described in the previous section was implemented on a real-world case study involving a bridge directly inspected by the authors. The structure is representative of typical bridges found within the Italian infrastructure network. As an initial phase, a visual inspection was performed following the LLGG2020 guidelines to assess the general condition and identify potential defects in the post-tensioned elements. Based on the recommendations in the proposed SI Guidelines, the number and positioning of test locations were then established. Given that the bridge is part of a non-strategic provincial road and lacks viable alternative routes, the selection of the most appropriate NDT technique for identifying voids in ducts was guided by the developed methodology. This was applied under three predefined decision-making contexts: the Accuracy-Driven Scenario, the Cost-Driven Scenario, and the Impact-Driven Scenario. 4.1. Case study The case study bridge is a seven-span structure with simply supported prestressed concrete girder decks, each approximately 22.1 m long, for a total length of 155.2 m. Each deck contains four post -tensioned concrete beams spaced at 2.55 m, with a known tendon layout. The beams use unbonded tendons: external beams contain five 42ɸ 5 tendons, and internal beams include four 42 ɸ 5 and one 13 ɸ 5 tendon. Crossbeams are also post-tensioned with two 26 ɸ 5 tendons each. The superstructure is supported by six reinforced concrete piers and two abutments. Based on the visual inspections and historical-critical analysis following LLGG2020, three distinct tendon populations, in accordance with the proposed SI Guidelines, were identified: Population 1 is composed by 42 ɸ 5 tendons in beams (126 total); Population 2 by 13 ɸ 5 tendons in central beams (14 total); and Population 3 by 26 ɸ 5 tendons in crossbeams (56 total). Risk assessments were conducted for each population by evaluating the probability (P) and consequence (C) indices, all leading to a medium risk class and medium traffic impact. Assuming a 20% defect rate and 75%