Analysis on Forced Vibration of Box Girders Considering the Effect of Bending Space
In this paper,by selecting the additional deflection as the generalized displacement of shear lag and taking into account the influence of shear lag additional deformation in the total kinetic energy of box girder system,a differenti-al equation and boundary conditions were established for the forced vibration considering the influence of bending space effect based on the theory of thin-walled structural elasticity and Hamilton's principle.Analytical solutions for forced vi-bration of simply supported and continuous box girders were provided under arbitrary harmonic loads.By introducing the stress and deflection amplification factors influenced by vibration frequency,this paper analyzed the proportion of the shear deformation and shear lag in the elementary beam results and the amplification factor distribution for simply suppor-ted and continuous box girders.The results show that the longitudinal dynamic stress considering the bending space effect is in good agreement with the finite element numerical solution.The greater the vibration frequency,the greater the stress and deflection amplification factor,the proportion of shear deformation effect,and the smaller the proportion of shear lag effect.The amplification factor of the simply supported box girder is much greater than that of the continuous box girder,and the higher the frequency,the greater the difference ratio between the two when vibrating at the same frequency.In the case of fundamental frequency vibration,the influence of shear lag can be neglected in the calculation of longitudinal stress of box girder,and the influence of shear deformation should be considered in the calculation of deflection.
box girderforced vibrationbending space effectwarping normal stressadditional deflectionamplifi-cation factor
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