Three examples of flutter analysis of cable-stayed bridges

There are multiple configurations permitted for a cable stayed bridge such as the number of spans, tower shapes, and cable arrangements. Therefore it is always important to study the behaviour of these types of structures against strong winds so that aeroelastic instabilities do not appear. This paper contains detailed aeroelastic analyses of three cable stayed bridges of very different configurations. Talavera Bridge over the Tagus River in Spain has only a single span of 315 m with a single pylon. The bridge has a central stay cable plane that supports the deck and two skewed planes of rear cables that allow the overall balance. The project of Miradoiros Bridge over La Coruña estuary in Spain has a classical configuration with a main span of 658 m and two secondary spans of 270 m each. The bridge has two lateral stay cable planes and an aerodynamic box girder. Finally, the future cable stayed bridge over the Forth in Scotland is studied. It has three mono-towers with a symmetrical arrangement resulting in two 650 m main spans and 325 m side spans. The deck superstructure is a single cell box girder with the stay cables anchored along the centre, so the bridge has two corridors. The software that analysed the aeroelastic instabilities of these bridges has been developed by the School of Civil Engineering at the University of La Coruña and it is based on hybrid methods. The hybrid methods are computational, although they need some coefficients and functions which must be obtained experimentally in an aerodynamic wind tunnel working with a deck sectional model. These experimental data permit the analysis of the complete structure considering the fluid-structure interaction between the wind flow and the deck.