Advanced retrofitting techniques with hybrid use of carbon fibre and external post-tensioning: A case study

The fast growth of the European countries and the great increase of vehicle production have determined two immediate consequences on the organization of the viability. On one side, a road network suitable for high speed communication has been developed or in some cases created. On the other, within and around cities, urban and local traffic has dramatically increased often without any clear planning or strategy and without any care about the interference between roads and urban network. Traffic demand has implied, through the years, an increasing number of roads with different level of importance and the related consequence of limiting or planning their intersections. The most economical and feasible way to face the new demand for intersections deriving from the increased number of roads and the mentioned problems has been to create a great number of flyovers and tunnels, with a clear preference for the first ones because of limited cost and ease of construction. Especially during the fifties, the need for a fast and massive reconstruction determined the creation of economical and easily repeatable structures such as simply supported decks for the case of the bridges. In Italy, differently from other European countries, there has been no meaningful evolution within the field of flyovers and the main typologies have not substantially changed form the ones with simply supported pre-stressed concrete beams used for the reconstruction after the World War II. The mentioned solutions have proved to be quite unreliable with reference to durability because of scarce detailing and because of the presence of bearings and expansion joints, actually known as critical points for the activation of corrosion phenomena. The paper illustrated a case study for the retrofitting of existing bridges aiming to reduce the need for future maintenance.