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选取剪力滞效应引起的附加挠度作为广义位移,在定义新的剪力滞广义力矩及广义翘曲位移函数基础上,将薄壁箱梁的剪力滞变形状态从初等梁挠曲变形状态中分离出来作为一种独立的基本变形状态进行分析。对广义翘曲位移函数引入两个修正系数以充分考虑剪力滞翘曲应力的自平衡条件。提出了剪力滞翘曲应力的简便计算公式,它与初等梁弯曲应力公式具有相同的形式。用能量变分法建立了剪力滞控制微分方程,以广义力矩、广义剪力、附加挠度及其变化率作为四个初参数,给出了微分方程的初参数解。对两跨连续箱梁模型的应力计算表明:本文计算值与实测值及其它文献给出的计算值均吻合良好,从而验证了该文分析方法的正确性。挠度计算表明:剪力滞效应使该箱梁在集中荷载和均布荷载作用下的跨中挠度分别增大17%和16%。
The additional deflection caused by shear lag effect is selected as the generalized displacement. Based on the definition of general shear moment function and generalized warping displacement function, the shear lag deformation state of thin-walled box girder is deduced from the flexural deformation of primary beam Separated out as an independent basic deformation state analysis. Two correction factors are introduced into the generalized warping displacement function to fully consider the self-balance condition of the shear lag warpage stress. A simple calculation formula for shear stress of warpage is proposed, which has the same form as that of primary beam. The governing equations of shear lag with energy variational method are established. The initial parameter solutions of the differential equation are given by taking the generalized moment, generalized shear force, additional deflection and its rate of change as the four initial parameters. The stress calculation for the two-span continuous box girder model shows that the calculated values are in good agreement with the measured values and the calculated values from other literatures, which verifies the correctness of the method. The deflection calculation shows that the shear lag effect increases the span mid-deflection of the box girder by 17% and 16% respectively under the concentrated load and uniform load.