Control of Flutter in Bridges

Abstract

The suppression of the flutter instability of a suspension bridge by means of feedback control is studied. To this end, the mathematical model considered consists of the midsection of a bridge, assumed to be fixed at the bridge towers. The partial differential equations of motion can be converted into a set of second‐order ordinary differential equations by using Galerkin's method. The design of optimal control is carried out by the independent modal‐space control method. The closed‐loop eigenvalues are selected so that the unstable flutter mode acquires a negative real part while the open‐loop frequency remains unchanged. A numerical example is given in which the flutter of a suspension bridge deck having aerodynamic characteristics similar to those of the original Tacoma Narrows Bridge is controlled.