On the influence of drag force modeling in long-span suspension bridge flutter analysis

Abstract

The present study aimed at investigating the role played by the description of the drag component on the predicted flutter velocity (and fre-quency) of very long-span suspension bridges. Based on a detailed finite element model of the central span of the Akashi Kaikyo Bridge, implemented in ANSYS, flutter analyses were run according to the following descriptions of the wind aerodynamic actions: (a) unsteady lift, moment and drag; (b) unsteady lift and moment plus steady drag, and (c) unsteady lift and moment, without drag. The finite element results are compared with those obtained by an in-house MATLAB code based on a semi-analytic continuum model. The latter includes flexural-torsional second-order effects induced by steady drag force in the bridge’s equations of motion, in addition to the unsteady lift and moment actions.