Bridge flutter and how to prevent it at low cost
8th International Conference on Structural Engineering, Mechanics and Computation (SEMC 2022)
Contribution to Conference
The mechanism of flutter and the main features of its mechanical description are explained. Its mathematical treatment as a two-parametric complex eigenvalue problem and a solution procedure for computing the flutter wind speed are outlined. It thus becomes clear why flutter is the all-dominating criterion in the design of very long-span bridges. Various known ways of stabilizing a bridge against flutter, such as the twin deck concept or movable control surfaces, are discussed and it is shown that all are associated with certain disadvantages, such as substantial additional costs or reliability and maintenance concerns. An alternative device is described that avoids these disadvantages: The eccentric-wing flutter stabilizer. In contrast to similar devices proposed in the past, the wings do not move relative to the bridge deck and they are positioned outboard the bridge deck to achieve a greater lateral eccentricity. This enables the wings to produce enough aerodynamic damping to effectively raise the flutter speed. Results of a parametric flutter analysis study are presented in which both the properties of the bridge and the configuration of the wings are varied. Conclusions can thus be drawn about the type of bridges for which the device is particularly effective and cost-efficient.