Suppression of Bridge Flutter by Active Deck-Flaps Control System

A theoretical study on an aerodynamic control method for suppression of the wind-induced instabilities of a very long span bridge is presented in this paper. The control system consists of additional control flaps attached to the edges of the bridge deck. Their rotational movement, commanded via feedback control law, is used to modify the aerodynamic forces acting on the deck and provides aerodynamic forces on the flaps used to stabilize the bridge. A time domain formulation of self-excited and buffeting forces is obtained through the rational function approximation of the generalized Theodorsen function. The optimal configuration of the deck-flaps system is found with respect to the performance index based on stability robustness of the system. A control system with the rotational center of the flaps that is located on the edges of the deck was found to be the most effective. It is also shown that this control system can provide sufficient aerodynamic damping and satisfactory stability robustness of the system with a relatively small flap size for the considered range of wind speed.