Base Frequency Formulas of Vertical Vibration for Earth-anchored Hybrid Cable-suspension Bridge

To calculate vertical frequency of the earth-anchored hybrid cable-suspension bridge (EAHCAB)conveniently, the earth-anchored hybrid cable-suspension bridge with double-tower was taken as research object. Frequency formulas for 1st vertical vibration modes were induced by the energy method and the influence of coefficient for tower flexural rigidity was introduced. Finally, the above analytic formulas were validated by the engineering project. The results indicate that the vertical vibration character of EAHCAB is slightly higher earth-anchored suspension bridge as the same of identical span arrangement, which is caused by the contribution of cable. The error between values calculated by the analytic formulas and the finite element method (FEM) meets with the requirement of conceptual design. The analytic formulas can be applied to select reasonable parameters for the EAHCAB in conceptual design stage.