Flutter aerodynamic instability is nowadays a well-known phenomenon; although, it still requires quite complex wind engineering knowledge and techniques to be analyzed.
- For Torsional Flutter the Critical velocity derivates from a Single degree of freedom torsional oscillation at the eigenfrequency of the bridge deck and the Flutter coefficient A2* that causes possible negative aerodynamic damping,
- For Classical Flutter, the flow is driven with coupled vertical and torsional oscillation. The transition from decaying to divergent oscillation has a critical velocity Ucrit. We assume the form of an unknown function that is made in order to facilitate the solution of an equation or other problem to be an oscillation and estimate Ucrit.
If there is no available data for the model, it can be also estimated as RM Bridge provides a CFD tool that can be used for a quick prediction of Flutter speed. The critical velocity is calculated using a quasi-steady approach for the torsional aeroelastic instability using the torsion-motion-related flutter derivative A*2 extracted from force vibration.
More information about Wind design Checks can be found at the link below, with an example.
communities.bentley.com/.../24-wind-design-checks