PSI - Issue 78

Livio Pedone et al. / Procedia Structural Integrity 78 (2026) 1991–1998

1993

Fig. 1. Schematic definition of urban areas and main steps of the proposed framework.

Urban areas are deemed as the analyzed system, which can be composed of many physical layers, including (but not limited to): building stock, road networks, water distribution networks (WDNs), gas pipelines, power distribution networks, and transportation. As pointed out previously, these layers are clustered and interconnected; thus, the possible (negative) interaction between layers should be considered in the seismic risk and loss assessment. In the proposed methodology, this is addressed through a “master - slave” approach. Specifically, it is supposed that earthquake- related damage to one layer (“master”) can lead to a loss of functionality of another layer (“slave”). In other words, the performance of the “slave” layer can be reduced due to a cascading effect from the “master” layer, even if the “slave” layer experienced no damage after an earthquake. Moving to a lower scale of analysis, the proposed methodology requires the evaluation of (aggregated) direct and indirect losses. Direct losses (DLs) are those related to damage to the layer’s components (single assets) and are typically associated with repair/reconstruction activities. DLs at the layer scale are evaluated through a simple sum of those obtained for each layer component (i.e., no considerations about interaction are needed). On the other hand, indirect losses (ILs) are those related to disruption and downtime, and can be significantly larger than the corresponding direct losses (e.g., Calvi et al., 2021). Evaluating indirect economic losses requires monetizing the indirect impact of earthquake damage to single assets, e.g. occupants’ relocation, business interruption, and missing revenues. In the proposed framework, the IL of a single asset is deemed due to (i) the experienced damage and the required recovery time, and (ii) possible cascading effects; the latter can be caused by damage to other assets of the same layer (intra-layer) or by damage to components of another layer (inter-layer). In the proposed framework, reference, maximum, and minimum values are evaluated for both DLs and ILs to account for uncertainties. Finally, at the scale of single components, loss analysis is performed based on the results of damage analysis. The latter is carried out considering different refinement levels of analysis, based on the available documentation and the specific needs of end-users and stakeholders. In this context, moving from a lower refinement level to a more refined one requires an increasing effort for data collection and higher computational cost; however, it is expected to return less uncertain results. In the proposed framework, the lowest refinement level (i.e., “Level 0”) only employs a basic knowledge of single assets, typically achievable for stakeholders: seismic hazard zone, construction period, construction material, and element use and importance. If a more detailed analysis is needed/preferred (i.e., “Level 1”), additional information is required. The latter includes , for instance, the buildings' global geometry (i.e., height, footprint, number of stories), utility network geometry (i.e., graph, pipe diameters), and soil details. These data can be collected by performing a “desktop study”, i.e. through web mapping platforms, cadastral documents, and/or available databases. Consequently, this refinement level requires a specific scientific background and technical