Long Term Behaviour of an Integral Abutment Bridge Designed for its Limit Length

The attainment of an Integral Abutment Bridge (IAB) is not only possible for newly built bridges but also taking advantage of the periodical refurbishment processes of simply supported bridges that can be turned into IABs, with feasible and economically convenient processes. A very interesting issue is the search for the maximum length attainable with this kind of structures, which is intrinsically related to the thorough understanding of the soil-structure interaction behind the abutments or next to the foundation piles. The case of the world record for IABs, which derives from the transformation of a simply supported flyover, namely Isola della Scala Bridge in Verona, Italy, is presented in the following. This built structure proves that the maximum length for IABs can exceed 400 meters and for the specific boundary conditions of the present case be around 500 meters. Another important aspect to be investigated is the long term response of such a kind of bridge. For the case presented, an attempt to understand the time-dependent overall behaviour of the structure is made by a series of repeated dynamic tests proposed at regular intervals. The first results are reported in the following.