Lighter and stronger: new generation of network arch bridges
The German border bridge over the Oder near Küstrin has a supporting structure that essentially consists of 88 carbon hangers. These were developed with the Swiss Federal Laboratories for Materials Testing and Research (Empa) and reduce emissions.
A new border bridge has been spanning the Oder near Küstrin since last year. It is held in place by a network arch with a span of 130 metres and 88 carbon girders. According to a recently published Empa press release, these carbon tensioning cables were developed by Carbo-Link, an Empa spin-off from Fehraltorf. The carbon carriers are made of carbon fibre reinforced plastic (CFRP).
This innovative material not only enables flexible processing, but also saves a large amount of carbon dioxide that would be released by conventional steel constructions. The use of carbon fibre beams significantly reduces the dead weight compared to conventional flat steel hangers. Around 500 tonnes of steel and 1350 tonnes of reinforced concrete were saved in the construction.
A major advantage of the new suspension cables is their high tensile strength and lower fatigue than steel. Most of the fatigue tests were carried out by a team from Empa’s Structural Engineering department and confirmed the necessary fatigue strength of the new CFRP material. “We have thus created the basis for a new generation of filigree network arch bridges with carbon hangers as load-bearing elements,” Giovanni Terrasi, Head of Empa’s Mechanical Systems Engineering department, is quoted as saying in the press release.
Visually, the new materials offer design freedom, as the Oder bridge shows. Carbon girders have already been used in other bridge constructions, but the special feature of the Oder bridge is that it is being used for the first time for heavy goods railway transport. Trains can pass over it at a speed of 120 kilometres per hour. The bridge has been honoured with both the German Bridge Construction Award and the British Bridges International Award.