Seismic risk assessment of urban areas. An integrated multi-scale and multi-refinement framework

Over the last decades, various methodologies for seismic vulnerability and risk assessment have been developed for various applications, ranging from single buildings to municipal, regional, and national scales. However, depending on the available information and the needs of end-users/ stakeholders, these methods differ in assumptions and refinement levels of analysis, making transitions and integrations across different scales challenging. Moreover, at the urban area scale, critical interconnections between different layers (e.g., building stock, utility networks) are typically neglected. In this context, as a part of a wider research project, this paper introduces an innovative framework for seismic risk assessment of urban areas. The proposed methodology relies on both a multi-scale and a multi-refinement approach. Urban areas are idealized as systems composed of various clusters and interconnected layers, which are themselves composed of single assets such as buildings, water pipelines, and road networks. Alternative refinement levels of analysis are employed for seismic vulnerability assessment of single assets, involving: i) typological-based approaches; ii) analytical/mechanical procedures, and iii) numerical (softwarebased) simulations. A key feature of the proposed framework is the evaluation of uncertainties for each refinement level and their propagation among the different scales. Moreover, the procedure accounts for the interaction (cascading effects) among different layers. To prove the concept, an illustrative application is presented for a virtual urban area. The proposed framework can support the decision-making for the management and planning of seismic risk reduction strategies, enhancing the safety and resilience of the community.