PSI - Issue 44

Emanuele Renzi et al. / Procedia Structural Integrity 44 (2023) 737–744 Emanuele Renzi et al./ Structural Integrity Procedia 00 (2022) 000–000

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The OI should not be understood in terms of updating or modifying the Bridge Guidelines, but as a regulation tool that allows them to be broader, easier, uniform and immediately operational, also for the purpose of standardizing the approach by operators. 4. Evaluation of seismic Attention Class according to the Bridges Guidelines The road and highway infrastructures must ensure a reliable service for very long periods of time, with a view to sustainability and safety. Seismic risk has a major impact on the functionality of transport systems, as an earthquake can compromise functionality of the network. Within transport networks, bridges can be considered "sensitive" structures to seismic stresses. The approach for seismic assessments and analyses used in the Bridges Guidelines is simplified and expeditious; however, all factors influencing seismic risk are taken into account through the definition of the Attention Class, using the typical risk definition in (1): = ∙ ∙ (1) In the Bridge Guidelines, primary parameters, of greater importance for classification and secondary parameters (shown in Table 1) have been selected for each factor based on experience.

Table 1. Primary and secondary parameters for the determination of seismical hazard, vulnerability and exposure factors Primary Parameters Secondary Parameters Hazard Peak ground acceleration and topographic category Subsoil category Vulnerability Structural scheme, light and material, Defect Level Design criteria Exposure TGM Level and average span light Road alternatives Type of body bypassed

Transport of dangerous goods Strategic nature of the work

The combinations of primary and secondary parameters take place according to an approach for classes and logical operators, combining the three factors (hazard, vulnerability and exposure) the class of seismic attention of the work under examination is obtained. It must be remembered that the three factors do not have the same weight in the definition of AC. Medium Hazard Class Exposure Class High Medium-High Medium Medium-Low Low

High

High

Medium-High

Medium

Medium High

Medium-High

Medium

Medium

Medium

Medium-Low

Medium-Low

Vulnerability Class Low

Medium

Medium-Low

Low

Fig. 2. Combination example