Seismic Assessment of a 14th-Century Stone Arch Bridge: Role of Soil–Structure Interaction

The study investigates the seismic response of the Azzone Visconti Bridge, which is a fourteenth century stone arch bridge crossing the Adda River in northern Italy. Based on previous extensive three-dimensional (3D) geometric surveys and mechanical characterization of both the soil constituting the riverbed and the masonry constituting the piers, a detailed 3D finite-element (FE) model was built. On-site ambient vibration tests have allowed dynamic characterization of the bridge. A preliminary sensitivity analysis on soil–structure interaction (SSI) parameters pointed out the key role of this boundary condition in the fitting of the mode shapes and their frequencies. Fully nonlinear dynamic analysis including the SSI have highlighted the safety levels for the structure and for the foundations.