Large-scale risk analysis is typically performed considering existing fragility curves, calculated in most cases without adequately accounting for local site amplification (SAmp) and soil-structure interaction (SSI) effects. Nevertheless, foundation flexibility and local site effects may lead to a substantial difference in the fragility or loss estimates. Including these effects on the city-scale vulnerability analysis is challenging due to the complexity of defining the whole interacting urban system. We propose a novel framework for the fragility assessment of structures considering the influence of SSI and local site amplification effects, suitable for large-scale applications. The applicability of the proposed approach is based on globally available data regarding the soil, the foundation, and the building portfolio. Site amplification is considered directly in the resulting fragility curves using site response analyses. An improved taxonomy is adopted to make the approach implementable in the OpenQuake software, introducing V_S,30 and H/B within the structural features as proxies for the site and SSI effects. Finally, following the performance-based earthquake engineering framework, the outcomes of the methodological framework are adopted to estimate the nominal probability of failure for selected building classes belonging to the majority of structural types of the city of Thessaloniki, Northern Greece. The main findings demonstrate that the conventional way of calculating fragility curves may lead to a different seismic risk evaluation, especially in soft soil formations.

For years, soil-structure interaction (SSI) has been a subject of interdisciplinary studies, although full-scale SSI experiments and the use of real data are rare. To study SSI in a well-known and controlled environment, a full-scale experiment, EuroMASS, was conducted at the Piana di Toppo test site in Northeast Italy. For the needs of the experiment, a simple structure consisting of a lumped mass overtopping a steel column on a concrete base was designed and assembled at the test site. In April 2022, a three-component instrumentation network was installed to record the seismic noise, weak earthquake motions, and active source signals to study the structure, the foundation, and the soil seismic responses. The experiment was designed to collect data that can be used for accurate dynamic characterization of the structure and analysis of wave propagation in the soil-structure system.