Integral Arch Bridge of Unlimited Length

Abstract

When it comes to the construction and maintenance of bridges, integral constructions have many economic advantages. The abutment areas of conventional integral bridges with lengths over 70 m often cause problems due to the length variations caused by temperature changes of the concrete in particular. A new bridge construction technology has been developed at the Institute for Structural Engineering of TU Wien to make the construction of very long integral bridges possible. The new construction method is based on the positive behavior of arch constructions. By using arches, which are situated between two fixed abutments, the temperature changes as well as length variations caused by creep and shrinkage are translated into a raise and a lowering of the tops of the arches. This “breathing” of the arches makes the construction of integral bridges of arbitrary length possible since all longitudinal strains are eliminated. Tendons, which connect the springers of the arches, enable the bridge construction in stages without temporary bracings, despite of slender piers. Further advantages are the reduction of bending moments of the arches and the piers for traffic loads positioned in a single span as well as the redundancy of the entire structure. To test the new technology under real conditions a 30 m long prototype, representing a segment of a very long integral bridge was built.