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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For each of the four types of risk - structural and foundational, seismic, hydraulic, landslides - the parameters of hazard, vulnerability and exposure are identified, considered most significant and distinguished in turn into primary parameters and secondary parameters, variable according to the type of risk considered, determined by processing the data collected by census and visual inspections. Depending on the value of the primary parameters, 5 levels are identified (low, medium-low, medium, medium high, high) defined with specific criteria and ranges of variation for each parameter. These classes are then corrected, by means of simple logical flows, by the value of the secondary parameters, which can in fact leave unchanged or raise or lower the class of primary parameters by one level, thus identifying the hazard class, the vulnerability class and the exposure class of the bridge. They are then combined with each other and provide the overall AC of the bridge, also declined in the usual 5 levels. The procedure is repeated, with the same logic, for the 4 types of risk identified, assuming the parameters of hazard, vulnerability and exposure significant for each of them. Known then the class of structural and foundational attention, the class of seismic attention, the class of hydraulic attention and that related to the risk of landslides, these are combined with each other to obtain the class of overall attention of the bridge (Fig. 1). The overall attention class therefore represents an approximate estimate of the risk factors, useful for the definition of an order of priority for the deepening of the investigations / checks / controls as well as for the planning of the necessary maintenance and structural interventions, but without being able to achieve the accuracy of the results of a complete risk analysis. 3. Operating Instructions for application of the Bridge Guidelines The Operating Instructions drawn up with the aim of providing a contribution of clarity and uniformity of interpretation are based on: • Experiences of supervision by the Agency on the road operators and related infrastructures; • Auditions on the application practices started by road operators in the transition process to the Bridge Guidelines; • Observations of professionals in charge of approaching the issue of risk classification of existing bridges; • Scientific studies present in literature; The preparation of an interpretative and guidance document – drawn up in the form of operating instructions inserted in the body of the text of the current Guidelines – has as its objective the identification by the operators of a common and uniform approach to the multi-level procedure that, starting from the census of the works, leads up to • explanation of the minimum information necessary for the determination of attention classes: structural foundational, seismic, hydraulic, landslide; with indication of priorities also related to the collection of such information; • concepts of inspection; • criteria for filling in the defect forms; • description of cases requiring special inspections; • indications on expeditious methods for risk assessment – in terms of hazard, vulnerability, exposure – divided into 4 separate insights that refer to the structural-foundational, seismic, hydraulic and landslide risks; • clarifications to § 8.3 "Safety Assessment" of the NTC; • clarifications on transitability checks; • clarification of the partial safety coefficients of permanent loads; • correction of the expression on the sample standard deviation of logarithms; • indications on methods for load testing on bridges/viaducts. the determination of ACs on the basis of which to activate the bridge checks. The salient contents of the OI for Bridges Guidelines can be grouped as follows: • indications regarding the prioritization of activities;