变截面连续箱梁剪力滞效应及其形成机制

为分析变截面连续梁的剪力滞效应,推导了变截面连续梁剪力滞效应的比拟杆控制方程,以某三跨连续梁为例检验了本文算法的正确性,讨论了箱梁梁高变化对连续箱梁剪力滞系数的影响,通过分析箱梁顶板和腹板内剪力流沿跨长的分布规律,探讨了梁高变化对连续箱梁正负剪力滞的影响规律。研究发现:连续梁正弯矩区呈现正剪力滞现象,负弯矩区的剪力滞现象与悬臂梁类似;梁高沿跨径方向的变化减弱了连续箱梁负弯矩区内剪力滞效应,但增大了正弯矩区的正剪力滞效应;工程设计时可以增大连续梁在负弯矩区内梁高的变化梯度,并减小正弯矩区内梁高的变化梯度,以最大程度地减小箱梁剪力滞效应。

Shear Lag Effect of Variable Box Section Continuous Girder and Its Formation Mechanism

In order to analyze the shear lag effect of continuous beam bridge with varying depth,differential equations of shear lag effect for variable-section continuous box girder were deduced and confirmed by the finite element analysis results of a continuous bridge with three spans.The effects of girder depths on shear lag coefficients and span lengths of positive shear lag region were discussed.The results show that the positive shear lag effects in the region are corresponding to positive moment,and negative shear lag effects of continuous bridges are similar to cantilever bridge.Girder depths variation with respect to span may decrease the shear lag effect in negative moment regions,but increase the shear lag effect in positive moment regions.It is recommended that the gradient of section depth's variation in negative moment regions should be as large as possible,but contrary in positive moment area,so as to minimize the shear lag effect of box girder.