Seismic behaviour of stone arch bridges in Sicily

The present paper concerns the seismic analysis of stone arch bridges, constituted of spans and piers in stone brick built in the Sicily in the XVIII and XIX centuries. The Ponte di Mare is located in Palermo over the Oreto river. It collapsed in 1772 due to river overflow, and was rebuilt in 1792. The bridge has three low arches: the central span is 12.15 m length and the keystone rise is about 4.00 m, while the lateral spans have both length of 10.40 m and keystone rise around 3.15 m. The Cinque Archi bridge overpass the Salso river linking the towns of Villarosa and Santa Caterina, respectively in the Enna and Caltanissetta provinces. It was built between 1857 and 1870. Each of the five arches has span lenght of 11.56 m and keystone rise of 3.72 m. The limit analysis are performed, based on the Heyman theory, assuming that the masonry is incompressible with no tensile strength and that sliding between units cannot occur. The results are compared with the Italian rules in order to evaluate the seismic safety.