GNGTS 2021 - Atti del 39° Convegno Nazionale

321 GNGTS 2021 S essione 2.2 A set of weighting coefficients, p j , were calibrated to derive an ‘equivalent shear wave velocity’, V Seq and an ‘equivalent soil-structure stiffness ratio’, σ eq , by considering the influence of both foundation embedment and soil layering in the calculation of weighted values of shear modulus, G eq , and mass density, ρ eq . For a given building slenderness ratio, h / b , the corresponding regression coefficients, α and β , were calibrated so that the frequency reduction ratio f * / f 0 (where f * is the soil-foundation-structure fundamental frequency) can be estimated as a function of σ eq through the expression reported in Fig.1. 2. Application to a case study: Matera The proposed procedure was assessed with reference to an extensive investigation carried out by CNR-IMAA (Tito Scalo, Potenza) throughout the city of Matera (Southern Italy), characterised by a peculiar geomorphological and lito-stratigraphic setting (Fig.2a). In the framework of CLARA project ( Cloud platform and smart underground imaging for natural risk assessment - Smart Cities and Communities and Social Innovation ), a total of 230 single-station ambient noise measurements (134 on the soil surface and 96 on masonry and reinforced concrete buildings) were carried out and analysed with the Horizontal to Vertical Spectral Ratio technique (Gallipoli et al, 2020). For this study, a set of 7 masonry buildings (shown in Fig. 2a) was selected, since located on deformable soil and characterized by a structural configuration similar to those considered in the parametric study reported by Piro et al. (2020). Fig.2. Matera: (a) geological map (b) reference schemes of SFS system for the application of the simplified approach.