大跨径钢-混组合梁桥主梁负弯矩区腹板弯-剪弹性屈曲分析

考虑翼缘弹性转动约束的腹板在弯、剪应力单独作用下的临界屈曲应力表达式可通过里兹能量法进行推导,然而在运用里兹能量法求解弹性转动约束边界下弯、剪复合作用的腹板临界屈曲应力时,会出现难以求解的复杂偏微分式。为掌握边界弹性转动约束的组合梁腹板在弯、剪复合作用下的屈曲特性,该文建立了考虑翼缘弹性转动约束的腹板有限元模型,分析腹板上、下边界弹性转动约束系数χ、弯剪应力比η、弯曲荷载应力梯度λ、宽高比γ 等参数对腹板弯、剪复合屈曲的影响。根据有限元计算结果重新拟合弹性转动约束的弯、剪复合屈曲修正方程,与一个钢-混组合梁负弯矩区腹板屈曲试验结果比较,试验结果与修正曲线误差为2.5%。

WED BUCKLING OF GIRDER IN LONG-SPAN STEEL-CONCRETE COMPOSITE BRIDGE UNDER SHEAR AND BENDING

The critical buckling stresses of web plates with boundary elastic rotational restraints under single shear or single bending can be obtained by Rayleigh-Ritz method, while in the case of web plates under composite shear and bending, the expression will become too complicated to solve. To solve the boundary rotational restraint web buckling under composite shear and bending, a finite element modal of a web plate with restrained flanges was built to analyze how the bending-shear correlation curve was affected by the flanges restraint coefficient, the ratio of shear-bending , the bending stress gradient λ and aspect ratio . Then a new bending-shear interaction equation of a web plate with restrained flanges was found by the finite analysis, the results had a good agreement with that of a steel-concrete composite girder experiment, the error was less than 2.5%.