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

5.2. Seismic attention class index CDA s The definition of the seismic attention class index CDA s considers the main parameters that influence the response to seismic actions of the bridges and road networks to which they belong. Similarly, to the definition of the structural and foundational attention class, the seismic attention class CDA s depends on hazard, vulnerability and exposure factors, determined through the combination of primary and secondary parameters. 5.2.1. Hazard (CDA s ) The evaluation of the hazard is associated directly to the peak ground acceleration and to the topographic category of the ground, combined with the soil classification. Knowing that, for our case study, the parameters were a g =0.126g, “T1” and “C” (Vs=270m/s 2 ) and the hazard classification computed by the flowchart is medium-high , as reported in Figure 7.

Figure 7. Flowchart for calculating hazard index CDA s .

5.2.2. Vulnerability (CDA s ) The evaluation method of the Italian Guideline requires the definition of 3 parameters. The first derives from the association of 4 secondary information, static scheme, mean span length, material type and spans number. This provisional class is then combined with the information associated with the design criteria (with or without seismic criteria) and the level of defects. Through flowchart reported in Figure 8, the vulnerability level is medium-high for the railway bridge.

Figure 8. Flowchart for calculating vulnerability index CDA s .

5.2.3. Exposure (CDA s ) The exposure class index was evaluated modifying the structural-foundation index in terms of exposure combined with a parameter that estimate the infrastructure strategicity. In our case study, the railwaybridge has been catalogued as strategic for the high importance of the network. The exposure definitive classification is high , see Figure 9.

Figure 9. Flowchart for calculating exposure index CDA s .

5.2.4. Final seismic attention class index CDA s The overall attention class index (CDA s ) relating to seismic risk is assigned based on the combination of the results of the previous assessments of hazard, vulnerability and exposure. No additional information is required, and the final level high automatically derives from the previous information, as is possible to see in Table 2.

Table 2. Final seismic attention class index CDA s .