Cable stayed bridges
are generally used for bridge spans between 150m and 350m. They are
often chosen for their aesthetics, but are generally economical for
spans in excess of 250m.
Cable stayed girders
were developed in Germany during the reconstruction period after the last
war and attributed largely to the works of Fritz Leonhardt. Straight cables
are connected directly to the deck and induce significant axial forces
into the deck. The structure is consequently self anchoring and depends
less on the foundation conditions than the suspension bridge.
The cables and the deck are erected at the same time which speeds up the construction time and reduces the amount of temporary works required. The cable lengths are adjusted during construction to counteract the dead load deflections of the deck due to extension in the cable
Decks are usually of orthortropic steel plate construction however composite slabs can be used for spans up to about 250m. Either box girders or plate girders can be used in the deck, however if a single plane of cables is used then it is essential to use the box girder construction to achieve torsional stability.