An innovative design concept for improving the durability of concrete bridges

It is proposed to build concrete bridges with tendons fully encapsulated in plastic ducts and without the use of reinforcing steel. In this case the durability of the proposed bridge depends only on the durability of the concrete because corrosion is no longer a determining factor regarding the lifetime of the structure. The requirements of the serviceability and ultimate limit states are fulfilled by providing post-tensioned tendons with strands fully encapsulated in plastic ducts and watertight anchorages. Since the proposed bridge does not contain any steel, which would be endangered by material-related corrosion, there is no need for insulation to the deck. Consequently, there is also no need for pavement and edge beams. This concept of building bridges represents a breakthrough with regard to sustainability and durability of concrete bridges and is applicable to small and mediumsized bridges. The method has already been implemented for the design of the Egg-Graben Bridge in the Grosarl valley in the province of Salzburg, Austria. Prior to the actual construction of the bridge, large-scale tests were performed to obtain practical values for the serviceability, ductility and loadbearing capacity of this structural system.