ND testing and establishing models of a multi-span masonry arch bridge

The Olla bridge, built in the second half of the nineteenth century, is an arch bridge consisting of five brick masonry arches with stone masonry piers. The bridge crosses the Stura river along the State Route SS 21, connecting the French border with the South-West part of the Piedmont region, and still represents a crucial node for the local commercial traffic. The paper summarises selected results of the extensive research programme carried out to assess the structural conditions of the historic bridge, which exhibited local damage of the arches and diffused surface decay. After a discussion on the common issues arising in the structural assessment of historical infrastructures, the Olla bridge is described and full details are given on the different steps of the investigation: (a) historical research, geomatic survey, on-site visual inspection and limited local tests on materials; (b) operational modal testing and analysis; (c) development of a FE model based on architectural research and selected modelling assumptions; (d) choice of the uncertain structural parameters and identification of the optimal parameters based on the experimentally obtained data.