Approximate expression of fundamental frequencies of large-span suspension bridges

Vibration characteristics of large-span suspension bridges are significant to their structural safeties and have been investigated extensively. Though powerful commercial finite element software is available to compute their dynamical features, approximate expressions, convenient and effective, are still valuable at preliminary design stage. In this paper, by means of Rayleigh´s method, the approximate expression of symmetrical, vertical, fundamental frequencies of large-span suspension bridges is derived accounting the kinetic energies of other structural components besides the main cables and the box girders. Comparison between analytical and finite element results reveals that the expression of this paper is useful and effective.