In research on the vertical bending mechanical properties of trapezoidal box girders with corrugated steel webs, the maximum angular rotation attributable to the in-plane shear deformation of flanges is traditionally considered as the generalized displacement function. However, this analysis method is very complex and the mechanical concepts are not well-understood. To address this, the presented work adopts the additional deflection induced by the shear lag effect as the generalized displacement function. Furthermore, the accordion effect, shear lag, shear deformation, and the self-equilibrium conditions of the shear lag warping stress and bending moment are considered comprehensively. The differential equations and the corresponding natural boundary conditions of the composite box girders in the elastic range are established using the energy variational method. Further, the closed-form solutions of the generalized displacements are obtained. The results of the analysis method presented, a modification of the traditional shear lag theory algorithm, had high agreement with finite element simulation results. In comparison to the traditional analysis theories, the accuracy of this modified method was improved. Thus, the method presented provides a strong basis for understanding the mechanical properties of composite box girders.

在波形钢腹板梯形箱梁竖向弯曲力学性能研究中，传统上将翼缘面内剪切变形引起的最大转角视为广义位移函数。但这种分析方法非常复杂，力学概念也不好理解。为了解决这个问题，本文采用剪力滞效应引起的附加挠度作为广义位移函数。此外，还综合考虑了手风琴效应、剪力滞、剪切变形以及剪力滞翘曲应力和弯矩的自平衡条件。采用能量变分法建立了组合箱梁弹性范围内的微分方程及相应的自然边界条件。此外，还获得了广义位移的闭式解。所提出的分析方法是对传统剪力滞理论算法的修改，其结果与有限元模拟结果具有很高的一致性。与传统的分析理论相比，该改进方法的准确性得到了提高。因此，所提出的方法为了解组合箱梁的力学性能提供了坚实的基础。