PSI - Issue 62

Anna Rosa Tilocca et al. / Procedia Structural Integrity 62 (2024) 1043–1050

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A.R. Tiloccai et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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Figure 3. Widespread defects on structural elements: Horizontal structures.

Figure 4. Widespread defects on structural elements: Restraints

According to the Italian Guideline, for each one macro- class such as “Over - Structure”, “Joints” and “Under - Structure”, the degradation level of a singular element is defined as maximum level among all defects level observed and reported in the element card. Subsequently, for each macro-class, the degradation level is computed in function of the percentage of defect levels of the elements that compose the relative macro-class: (i) if > 50% of levels are medium , the macro-class level is medium , (ii) if < 50% of levels are medium , the macro-class level depends on prevalence between low or medium-low levels; (iii) if on the element card there is one defect level equal to medium-high or high , the macro-class level is medium-high or high . Finally, knowing the degradation levels of all macro-classes, the infrastructure levels is defined as the maximum level obtained. For the railway bridge treated in this paper, 23 macro- classes “over - structures” were computed with degradation level rangin g from low and medium-low , 1 macro- class “joints” with medium-low level and 24 macro- classes “under - structures” with l evel from low and medium-low were also evaluated. Therefore, the degradation level for the entire infrastructure is medium-low . 5. Level 2: railway bridge classification and attention class index (CDA) The risk associated with bridges is approximately estimated using the attention class index (CDA). In fact, it is considered misleading to talk about actual risk, as its analysis requires more complex and in-depth assessments/investigations than the simple and expeditious ones expected by level 2 and cannot be based only on information collected through onsite visive inspections. The attention class index is, however, an approximate estimate of the risk factors, useful for defining an order of priority for in-depth investigations/controls as well as for planning the necessary maintenance and structural interventions. The proposed attention class index (CDA) is inspired by the common risk definition scheme, and it is the result of the combination of three main factors: hazard , vulnerability and exposure . Specifically, it is convenient to distinguish four types of risk: structural-foundational , seismic , geotechnic and hydraulic . When CDA index associated with the four risks are known, they are then combined together in order to obtain the attention class index (CDA) of the bridge that consent to plan future interventions. 5.1. Structural-foundational attention class index CDA sf The definition of structural-foundational CDA sf is based on consideration principal parameters that influence the structural behavior of the infrastructure. Common parameters related to traffic-load entity and its frequency, structural characteristics and functioning conditions of the infrastructure and of the network are considered.