The significance of soil-foundation compliance on the dynamic identification of the Chiaravalle viaduct

The paper addresses the significance of soil-structure interaction on the dynamic behaviour of the “Chiaravalle viaduct”, based on ambient vibration measurements and numerical simulations through a finite element model. The viaduct is located in Central Italy and is founded on piles in an eluvial-colluvial soil deposit. Experimental modal properties are evaluated by means of the operational modal analysis on accelerometric data, and the role of soilstructure interaction in the interpretation of tests is identified by means of a refined finite element model of the viaduct. In the soil-structure interaction models the local site conditions in correspondence of each bridge pier (resulting from geotechnical and geophysical investigations) are taken into account in the definition of the soilfoundations impedances. Comparisons between the experimental and numerical results highlight the role of the pile-soil-pile interaction, the radiation problem, the pile cap embedment and the variability of the soil stratigraphy along the longitudinal direction of the viaduct in the interpretation of the experimental data.