Suspension bridges are long, slender flexible structures which have the potential to be susceptible to a variety of types of wind-induced instabilities, the most serious of which are divergence (due to stationary wind forces) and flutter (due to aerodynamic forces). Flutter occurs at certain wind speeds where aerodynamic forces acting on the deck feed energy into an oscillating structure, so increasing the vibration amplitudes. If this situation is approached the basic safety of the bridge is threatened. This paper describes a computational method for predicting flutter speed based on a modal technique. A selection of the lowest vertical and torsional natural mode shapes is included with the aerodynamic forces in an interaction analysis, which yields an unsymmetric matrix eigenvalue problem. Flutter instability is indicated when, at some wind speed, one of the complex eigenvalue pairs resulting from the solution of the eigenvalue problem has a zero real part and a non-zero imaginary part. (Author/TRRL)

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  • Corporate Authors:

    Butterworth Scientific Limited

    Journals Division, P.O. Box 63, Westbury House, Bury
    Guildford, Surrey  England  GU2 5BH
  • Authors:
    • AGAR, TJA
  • Publication Date: 1989-4

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Filing Info

  • Accession Number: 00493239
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD, TRIS
  • Created Date: May 31 1990 12:00AM