Strengthening Bridges with Unbonded Prestressing

In response to the need for a simple, efficient method to strengthen existing bridges, the use of unbonded prestressing has gained wide acceptance. The use of unbonded prestressing in bridge construction is not new. Several bridges were built this way earlier this century. The first in Germany was the bridge at Aue in 1936, designed by Franz Dischinger. This bridge, built before the wide development of prestressing steel, is prestressed by high strength steel bars. The use of unbonded prestressing is a major trend in the construction of bridges today, along with the development of high strength prestressing steel and anti-corrosion systems for unbonded tendons. This technology, not only for new bridges, increases the load-carrying capacity of a bridge, as well as enhancing the structures durability.