PSI - Issue 44

E. Renzi et al. / Procedia Structural Integrity 44 (2023) 355–362 E. Renzi et al./ Structural Integrity Procedia 00 (2022) 000 – 000

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will be efficiently targeted. Without prejudice of the need to carry out the assessments of the transport relevance (according to point 1.4 of the GMEB), the assessment expressed in terms of ACs related the seismic risk (of the various assets that make up the regional and local road networks) and provided by the application of the GMEB, will be a fundamental support, for the interested parties (public and private), in order to define emergency plans related to the level of seismic risk exposure. In particular: - targeted interventions will be evaluated in terms of achievement of a levelling of the Seismic AC and the OAC of the bridges that compose the reference network and, consequently, an improvement in the resilience of a specific road segment; - for the emergency plans it will be possible to take into account the “Structural/Operational” and “Seismic” ACs of the bridges, that connect to areas potentially subject to important events (identifiable from the seismic hazard maps) and characterized by a high population density (Report ISTAT 2020, Territory) and/or by a particular fragility of the territory; at a regional level, by carrying out simulations, it will be possible to predict, depending on where a seismic event may occur, the sections of the network that could best allow the transit of emergency and supply vehicles. Moreover, the assessments of resilience, conducted based on the AC, need to be extended to tunnels and other road structural components, which in the same way can constitute weak links in the chain of structural assets of the road infrastructure. The Seismic AC, which identifies the seismic risk of a bridge, carries within itself an assessment of the aspects that identify the seismic hazard of the site in which the asset is built, the vulnerability of the structure and the exposure and, therefore, represents an initial estimation of the structural performances of the asset within the territory and the transport network; the structural monitoring systems, that are implemented or that will be implemented in the subsequent years on bridges tunnels and secondary structures of the national network, and will be able to provide useful data on the response capacity of the structures to the events that may occur. To help to clarify how the resilience of a road section/network can be quantified and how it can be possible to deal with emergency situations (as well as to develop seismic retrofitting plans and to reduce economic disruptions), reference can be made to a couple of important international studies, as reported below. Nicolosi et al., 2022 have proposed an innovative methodology to stochastically assess the economic resources needed to restore damaged infrastructures that uses three types of “Measures of Resilience (MoR) indicators” , which take into account the costs of restoring infrastructures damaged by a calamitous event; in particular, in measuring resilience as the sum of the transport cost and the resources to be used to fix the damages; it is presented a method that relates the recorded Peak Ground Acceleration (PGA) with the aforementioned costs, to support decision-making aimed at optimizing future investments. Considering the resilience as the ability of a system to respond to and recover from adverse events (Susan L. Cutter et al., 2008), it is possible to associate at least two main objectives with the characteristic under consideration, namely, as suggested by Eiichi Teniguchia et al., 2012, “lifesaving” and “economic disruptions reduction”. In particular, this study prop oses a conceptual model for dealing with emergencies structured in three phases: in the first phase the objective is to improve the robustness of the network in order to prepare it to respond promptly to any unexpected events; the second phase contemplates both the analysis of the previous phase and the rapid allocation of the resources to be used for those assets with higher influence on the network capacity; the third phase has the objective of the rapid and efficient recovery of the system. In this perspective, a road network risk assessment must be analyzed in the light of the existing relationship with the territory, which must be analyzed and read on the basis of their mutual influences in terms of accessibility and usability. Worthy of reflection is the data provided by the Territory Report 2020 (ISTAT, 2020), such as the density of the motorway network evaluated in: km per 100 km 2 , km per 10,000 inhabitants, km per 10,000 cars or accessibility to the motorway network measured in terms of time. Considering that the areas with the greatest seismic risk, generally, are also those characterized by a lower density of the motorway (since the conformation and geology of the soil are in a certain manner linked to the possibility of having a seismic events as well as to the difficulty of making fast road connections), it is essential to apply the GMEB methodology of risk assessment to identify and qualify the motorway sections ’ resilience with regard to the geographical areas offering limited alternatives in terms of transport connections, especially in cases of high population density and/or in the presence of particularly vulnerable buildings.