Analytical study on flutter suppression by eccentric mass method on FEM model of long-span suspension bridge

Abstract

A method of suppression of flutter in long-span bridges based on the concept of eccentric mass is presented in this paper. The auxiliary mass is placed on the windward side of a bridge deck to shift the center of gravity, and thus, the aerodynamic moment acting on the deck is reduced, resulting in an increase in the flutter wind speed. The state-space model of aerodynamic forces on the bridge deck section with eccentric mass is derived through a rational function approximation of unsteady aerodynamics. The parameters of the rational function model of a section of the bridge are obtained from the flutter derivatives experimentally determined. Then, the FEM model of full suspension bridge with main span of 2500m is derived. It is shown from numerical study that addition of an eccentric mass gives a significant improvement in the flutter wind speed. Distributing the eccentric mass in the center-span is found to be the most effective.