关键词: 箱形梁, 能量变分法, 剪力滞, 高次抛物线

Abstract: Considering the shear lag longitudinal displacement, five times and six times parabola are adopted respectively to reflect the changing range of shear lag effect of thin wall box girders. And the calculation formula and boundary conditions of corresponding differential functions of shear lag effect are obtained by the adoption of energy variation method. According to the changing rules of different parabolic function of the displacement of shear lag effect in several common loading and bearing forms, a comparison between them are carried out. The results show that the vertical displacement box function is more precise when times get higher than three times parabola adopted in usual shear lag effect, which offers references and guides to the further study of shear lag effect.

Key words: box girder , energy variation method , shear lag effect , high order parabola ;