PSI - Issue 84

Pasquale Bencivenga et al. / Procedia Structural Integrity 84 (2026) 264–271

270

, ̅̅̅̅ = , − , , , , − , , = + , ̅̅̅̅ 2

(2)

(3)

In Equation (2), I C,c denotes the complementary value of I C , while the subscripts min and max reads as the minimum and maximum values of the parameter among the considered sample, respectively. This index integrates information on both structural condition and regulatory adequacy, providing a comprehensive measure of bridge criticality. For interpretative purposes, the results (Figure 3) were classified into four classes of equal amplitude. Approximately 44% of the bridges fall within the lowest class (I P < 0.25), corresponding to the safest conditions, while 36% are included in the second class (0.25 ≤ I P < 0.50), indicating moderate levels of criticality. Around 12% of the bridges belong to the third class (0.50 ≤ I P < 0.75), and the remaining 8% fall into the highest class (I P ≥ 0.75), representing the most critical structures. Bridges in this upper class may be prioritized for Level 4 assessments, involving detailed structural evaluations, targeted maintenance interventions, and potential retrofitting measures. Notably, one bridge exhibits a Priority Index of 1, with advanced signs of degradation observed in the reinforcement bars of deck elements, while its simplified safety index is equal to 1, as it was originally designed according to the 1945 standard. Overall, this classification provides a clear and practical overview of bridge criticality across the inventory, highlighting both the safest and the most vulnerable structures. It offers a straightforward and data-driven basis for planning inspections, maintenance, and resource allocation, ensuring that the most critical cases receive timely attention.

100%

80%

60%

44%

36%

40%

20%

12% 8%

0% Percentage of bridges [%]

<0,25

0,25-0,50 0,50-0,75 0,75-1,00

I P [-]

Fig. 3. Priority index (I P ) combining defect level and safety index factors

4. Conclusions This study presents a scalable approach to support efficient bridge management through the combination of the results of Level 2 and a simplified version of the Level 3 as the defined in the current Italian Guidelines for existing bridges. The methodology combines geometric and typological features with defect evaluation and a comparison between historical and current design codes. It was applied to approximately 90 road bridges in the Campania region, with detailed analysis focused on 50 representative structures classified as Medium and Medium-High Attention Class. Defect levels (I D ) were generally low to medium across the inventory, with only a small portion of bridges exhibiting higher severity that may require closer monitoring. The analysis shows that most bridges exhibit moderate safety margins, strongly influenced by the design standards in force at the time of construction. The lowest design related indices (I C ) were observed for bridges designed according to post-war regulations (1945 Circular), while the majority of bridges falls within intermediate ranges for bending moment and shear. To ensure a consistent combination of the two indices, an inverse min–max normalization to the interval [0,1] was applied to I C prior to its combination with I D . It should be noted that this approach enables meaningful prioritization within the selected sample, as the priority ranking is defined relative to the bridges managed by the same administrative authority. To integrate structural and regulatory aspects, a Priority Index (I P ) was introduced, providing a comprehensive measure of bridge criticality. According to this index, approximately 44% of the bridges fall within the lowest class,