Efficient cable arrangement in cable stayed bridges based on sensitivity analysis of aeroelastic behaviour

Construction of cable supported bridges has experienced a great impulse in the past decade. Bridges having more than 800 m of span length were built in France and Japan and some bridges with span length of more than 1 km are going to be built, such as the Stonecuters bridge in Hong-Kong, and the Chongming in China (Fig. 1). Because of the increasing length of this class of bridges, they are becoming prone to phenomena like flutter in a similar way than long span suspension bridges. Cable stayed bridges may present a few different alternatives for the cable system. At least harp, fan or modified fan arrangements can be discussed at the beginning of the design. Also variations in the number of cable planes can be studied. Usually, during the design process changes are made by carrying out a number of analyses and using trial and error techniques relying in heuristic rules that are based upon the particular skills of the engineer. This approach can be inefficient in new problems and commonly it needs to be supported with results coming from experimental testing which makes more expensive the whole design process. Instead of that, an approach based in sensitivity analysis can be very helpful for the designer.