Wind-induced flutter of bridges with streamlined, plate-like cross-sections occurs as coupled torsional and vertical oscillation. Prediction can possibly be facilated by representing the spatial system by a generalized 2-DOF system. This may, however, be inadmissible or may lead to extremely conservative results if the modes of torsional and vertical vibration differ strongly. Flutter prediction should then be based on spatial modeling. Classical methods of aircraft engineering for solving the spatial problem proceed from differential equations of motion or make use of variational principles. For appliations in bridge engineering, the finite-element concept proves to be more efficient. In this paper, two beam elements of different complexity are presented. Formulation and solution of the resulting MDOF equations of motion are described. Results of numerical calculations are stated.
