Torsional flutter mechanism of two-edge girders for long-span cable-stayed bridge

The aim of this study is to obtain a series of fundamental data on aerodynamic characteristics of two-edge girders, such as flutter instability and vortex-induced vibration. Two-edge girders have, in general, structural and economic advantages for long-span cable-stayed bridges. The effect of geometrical shape of girders, their location and incidence angle of flow on the two-edge girders aerodynamics was investigated by a series of wind tunnel tests. The aerodynamic derivatives, associated with flutter instability, are obtained by 1° of freedom (1DOF) heaving/torsional forced vibration method. Furthermore, flutter mechanism is investigated by the unsteady pressure measurement under 1DOF heaving/torsional forced vibration. It is clear that flutter instability of two-edge girders is closely related with the exciting source on the downstream side of upper and lower surface on the deck.