移动荷载作用下薄壁曲线箱梁剪力滞效应分析

Analysis on Shear Lag Effect of Thin-Walled Curved Box Girder Under Moving Load

采用有限元法研究了移动荷载作用下曲线箱梁剪力滞效应及主要结构参数对剪力滞效应的影响。结合曲线箱梁设计参数合理取值范围,通过建立不同腹板宽度、不同曲率半径下的曲线箱梁空间板壳有限元模型,对简支曲线箱梁剪力滞效应进行参数化分析,得到了荷载运动到跨中截面时跨中顶板应力分布及内外侧剪力滞系数变化规律。根据分析结果,利用最小二乘法提出了计算曲线箱梁剪力滞系数经验公式。分析结果表明:在移动荷载作用下,动剪力滞系数峰值出现在顶板与腹板交界处,最大值接近1.6,剪力滞效应严重;腹板宽度和曲率半径对箱梁剪力滞效应的影响十分明显,二者相互影响;外侧结点剪力滞系数峰值大于内侧;腹板宽度的增大和曲率半径的减小使外侧结点剪力滞效应更加显著,在车辆荷载作用下箱梁外侧部分更易遭到破坏。经验公式的计算结果与有限元分析结果相对误差为3.27%,满足工程计算要求。

Shear lag effect of curved box girder and the influence of main structure parameters on it under moving load were investigated by using the finite element method.Considering the reasonable ranges of design parameters of curved box girder,parametric analysis on shear lag effect of simply supported curved box girder was performed by setting spatial shell finite element models under different web widths and curvature radii,therefore the change rules of stress distribution in the roof of mid-span section and shear lag coefficient inside and outside were obtained when the loads moved to the mid-span.Based on the analysis,the empirical formula was proposed to calculate shear lag coefficient of curved box girder with the least square method.The results show that under moving loads,the peak dynamic shear lag coefficients present at the junction of roof and web,the maximum of it nearly reaches 1.6,shear lag effect is severe.Shear lag effect is greatly influenced by web width and curvature radius which affect each other,peak shear lag coefficients of outer nodes are bigger than that of inner /or outer nodes,the increasing of web width and decreasing of curvature radius make shear lag effect more prominent.The outer part of box girder is damaged more easier under vehicle loads.The relative error between the results of proposed empirical formulas and finite element method is 3.27%,which meets the need of engineering calculation.