PSI - Issue 84

172 L. Zoccolini et al. / Procedia Structural Integrity 84 (2026) 167–174 construction details and materials is represented by , which is set to 7. A lack of redundancy in the post-tensioning system, cable ducts with curved profiles, and match-cast glued segmental joints are some of these hazards Similarly, the condition factor is assumed to be uniform for all the spans analyzed. Based on available information on the state of conservation, a total of 29 hazards affecting the structure's current condition have been identified. The main hazards include cracks in post-tensioned concrete elements, damaged or missing bridge joints, and delamination and/or expulsion of concrete attributable to corrosion. In accordance with CS465, the is set at 10, the maximum value allowed by the standard. Although the number of hazards identified exceeds this threshold, CS465 imposes that the must be between 0 and 10; consequently, when 10 hazards are exceeded, the factor is saturated and further defects do not increase the score. Lastly, the severity of the effects that a possible collapse or disruption of bridge service may have is used to establish the consequence factor . This factor remains constant across the spans under consideration, since all the spans are part of the same infrastructure. The is set to 5 in compliance with CS465, a value that reflects the high impact of an operational railway line on the deck. In the case of a bridge collapse or reduced performance, this arrangement has serious implications for safety, service continuity, and socio-economic effects. Once all the risk factors required by CS465 are defined and the corresponding scores assigned for each span, the risk rating can be calculated. The risk rating is expressed as a percentage and is obtained by combining the individual factors, as shown in Eq. 1. The risk factors adopted for the different span types considered in the case study, along with their corresponding risk ratings, are summarized in Table 1.

Table 1. Summary of the risk rating approach

Isostatic Spans

Continuous Beam spans

Year of construction factor Form Factor Vulnerable details and materials factor Condition factor Consequence factor Risk rating R [%]

Review Data

Factor Value

Review Data

Factor Value

Post 1996 Very High 7 hazards 29 hazards

1

Post 1996 Medium 7 hazards 29 hazards

1 8 7

12

7

10

10

Railway on the deck

5

Railway on the deck

5

62.6

58.7

4.2. Mean hazard risk level scoring approach The mean hazard risk level scoring approach is applied during the risk assessment phase to identify the hazards associated with post-tensioning systems for each span. Due to the lack of specific inspection for the analyzed spans, the definition of hazards is based exclusively on general information available for the entire infrastructure. In accordance with CS465, the analysis considers the main hazard scenarios typical of post-tensioned structures, including hazards associated with construction details and materials, as well as those related to the state of conservation already analyzed in the previous approach. In addition, the history hazards and assessment hazards are considered. Of the seven hazards identified in relation to vulnerable details and materials, 4 are classified as medium level hazards and 3 as low-level hazards. Similarly, of the 29 hazards associated with the state of conservation, 27 are medium-level, and 2 are low-level. In addition to these, there are two low-level hazards related to historical hazard and a further low-level hazard related to assessment hazard. After that, each hazard is assigned a score ( ) ranging from 1 to 6 based on its intensity. The mean hazard risk level score (H) is then obtained using Eq. 2 as the average of the contributions from all considered hazards. Table 2 summarizes the results of the mean hazard risk level scoring approach.