Study of Free Vibration Characteristic of Continuous Box-Girder Based on Hamilton Principle

Based on Hamilton principle, the differential equation of free vibration and the corresponding boundary conditions of continuous box girder with consideration for the shear lag effect meeting self-equilibrated stress, shear deformation as well as rotational inertia were induced. The ANSYS finite element solutions were compared with the analytical solutions by calculation examples and the validity of the proposed approach was verified. The obtained formulas developed the shear lag theory. Some meaningful conclusions for engineering design were obtained. The contribution of the shear lag effect decreases each order natural frequency of the continuous box-girder, at the same time the higher the order natural frequency is, the greater the influence of shear lag effect on natural frequency of continuous box-girder is. The shear-lag effect of continuous box girder increases when frequency order rises, and increases while span-width ratio decreases.