ABSTRACT

ABSTRACT: Theoretical and experimental investigation of an historic cable-stayed bridge is described in the paper. The investigated cable-stayed system, known as Carpineto bridge, was designed by R. Morandi and is placed on the freeway between Potenza and Sicignano (Italy). The bridge includes a main span, 181.0m long, with two cantilevers suspended by inclined stays and connected by a central simply supported drop-in girder. The structure is characterised by the adoption of pre-stressed concrete stay-beams, as it happens in other bridges designed by R. Morandi in the 60's, like the Wadi-KufBridge in Spiac (Libya), the Magliana Viaduct in Rome (Italy) and the Polcevera Creek Viaduct in Genoa (Italy). The cable stays consist of pre-tensioned steel strands encased in a pre-stressed concrete shell; such unusual elements have made famous the bridges designed by Dr. Morandi in the bridge engineering community. The construction of the stays was carried out in successive steps. At the completion of the deck, the stays were made only of conventional tendons which carried the dead load of the cantilever girder. Successively concrete beams were cast in situ, in a segmental way, along the main tendons; the concrete beams were then pre-stressed by means of additional tendons. Finally, all the tendons were grouted so that the post-tensioned stay-beams supported almost all the live loads.