| Abstract: | A linear theory is developed for the free, torsional vibrations of the single-span, boxgirder suspension bridge. Both symmetric and antisymmetric modes are considered. For the symmetric modes, which induce additional cable tension, it is shown that it is imperative to include the elasticity of the cables if correct solutions are to be obtained. Three examples of bridges with widely differing properties are presented to illustrate the applicability of the theory. Orthogonality of the torsional modes of vibration is proved in Appendix I and the modification to the analysis, required when rigid centre ties are present, is outlined in Appendix II. The theories presented herein can be readily extended to the three-span bridge. |
