Aeroelastic instability of long-span bridges: contributions to the analysis in frequency and time domains

According to research currently developed by several authors (including the present ones) arnmultimode approach to the aeroelastic instability can be appropriate for suspension bridges with very longrnspan and so with close natural frequencies. Extending that research, this paper deals in particular with: i)rnthe role of along-wind modes, underlined also by means of the flutter mode representation; ii) the effectsrnof a variation of the mean wind speed along the span. A characterisation of the response in the timerndomain by means of an energetic approach is also discussed.