中文摘要：

为了考察变截面薄壁箱形梁考虑大挠度和剪力滞效应的受力性能，依据势能变分原理，考虑箱梁翼缘正应力的剪力滞效应和结构竖向挠度的几何非线性影响，将5个广义位移函数（竖向挠度、扭转角和3个剪滞翘曲位移）用样条函数展开，使变截面薄壁箱形连续梁的大挠度问题转化为求解非线性代数方程组问题，并采用Newton—Raphon迭代法求解。研究结果表明：要合理地分析薄壁箱形梁的受力状态，应对翼缘板的悬臂板、顶板和底板分别取不同的剪力滞翘曲位移函数进行计算；变截面连续箱梁受力比相应等截面薄壁箱梁的压力更为合理，更能适应连续梁箱梁截面内力沿梁纵向的变化：大挠度对变截面连续梁箱梁内力、位移的影响程度取决于荷载。

英文摘要：

In order to study the mechanics behavior of the thin-walled box continuous girder with variable cross-sections considering the influence of large deflection and shear lag, by mean of potential variational theories, considering the influence of the shear lag effect of flange＇s stress and the geometry nonlinear of vertical displacement, and evolving five generalized displacements with the spline function, the large deflection problem of the thin-walled box continuous girder with variable cross-section was transformed to the nonlinear algebra equation group, which was solved with Newton-Raphon iterative method. The calculating results show that different shear lag warp functions to cantilever, top and bottom plate should be taken for analyzing the mechanics behavior of the thin-walled box continuous girder reliably. The thin-walled box continuous girder with variable cross-section has more reasonable stress state and more adaptable for the longitudinal change of internal forces in the thin-walled box continuous girder than that with equal cross-section. The influence of large deflection on the stress and displacement of the thin-walled box continuous girder with variable cross- sections depends on the load.