ABSTRACT
ABSTRACT: Rehabilitation and strengthening of existing concrete structures has become more and more in focus during the last decade. All over the world there are structures intended for living and transportation. The structures are of varying quality and function, but they are all ageing and deteriorating over time. Some of these structures will need to be replaced since they are in such a bad condition. However, it is not only the deterioration processes that make upgrading necessary, errors can have been made during the design or construction phase so that the structure needs to be strengthened before it can be used. The causes for repair and/or strengthening can be many, but normally deteriorated concrete, steel corrosion, change of use, increased demands on the structure, errors in the design or/and construction phase or accidents are governing factors. Many methods to repair or/and strengthen concrete structures exists such as concrete overlays, shotcrete, use of external prestressed tendons, just to mention a few. Prestressing is in particular interesting with several comparable advantages to other methods. In this paper the use of prestressing for repair and strengthening are briefly discussed and tests on concrete T-beams with external Prestressed tendons of steel or CFRP (Carbon Fibre Reinforced Polymer) are presented. The tests shown that prestressing is a very effective way to increase the existing load carrying capacity of existing concrete members. The presented project is a small part of a larger European funded project, the “Sustainable Bridges”, where the aim is to evaluate the load carrying capacity and life of existing railway bridges with the purpose to increase existing load carrying capacity with 25% and the train speed to 350 km/h.
