Estimation Frequency Formulas of Vertical Vibration for Self-anchored Cable-suspension Bridge

To calculate vertical frequency of the self-anchored hybrid cable-suspension bridge conveniently, the self-anchored hybrid cable-suspension bridge with double-tower was taken as research object. Frequency formulas for the first symmetric and asymmetric vertical vibration modes were induced by the Rayleigh method and the influence of coefficient for tower stiffness was proposed. Finally, the presented analytic formulas were validated by the engineering project. The results indicate that the vertical vibration frequency of self-anchored hybrid cable-suspension bridge is slightly higher than that of the self-anchored suspension bridge. Tower stiffness which should be correctly considered in frequency calculation has a great influence on the first symmetric vertical frequency, while it has no effect on the first asymmetric vertical frequency. The error between values calculated by the proposed formulas and the finite element method (FEM) meets with the requirement of conceptual design. The proposed formulas can be applied to select reasonable parameters for the self-anchored cable-suspension bridge in conceptual design stage.