A simplified evaluation in critical frequency and wind speed to bridge deck flutter

This paper deals with the instability problem of flexible bridge decks under an approaching crosswind flow within framework of bimodal flutter involving fundamental vertical and torsional modes of bridge vibration. Start from simplifying coefficients from terms of the cubic and quartic polynomials derived from singularity conditions of an integral wind-structure impedance matrix and by using the quasi-steady approach, the approximated formula for calculating onset flutter of the aeroelastic bridge system are proposed. A good agreement is obtained comparing predictions on the onset flutter by the proposed and available formulas for several study cases from the existing bridges with difference of structural and aerodynamic characteristics of given bridge deck.