扁平钢箱梁剪力滞效应分析

利用有限元法研究了扁平钢箱梁在集中荷载和均布荷栽作用下的剪力滞效应。结合扁平钢箱梁设计参数的合理取值范围, 分析了截面宽度和高度、顶板和底板厚度、纵隔板与横隔板的厚度和间距等参数对剪力滞效应的影响。根据理论分析结果, 应用回归分析法提出了扁平钢箱梁剪力滞系数的实用计算公式, 并将计算结果与有限元分析结果进行对比分析。分析结果表明: 跨宽比对剪力滞系数影响最显著, 当跨宽比由1.786增大至8.926时, 顶板与底板处的最大剪力滞系数分别由1.40、1.32减小为1.07、1.06, 减少约20%;当纵隔板厚度由10 mm增大至30 mm时, 剪力滞系数在边腹板处减小约7%, 而在其他位置变化小于1%;纵隔板间距与梁宽比由0.430增大至0.582时, 剪力滞系数增大约9%;其他参数变化对剪力滞系数的影响均可忽略。实用计算公式的计算结果与有限元分析结果的相对误差小于1%, 说明公式计算精度较高, 满足工程计算要求。

Shear lag effect analysis of flat steel box girder

The shear lag effects of flat steel box girder under concentrated and uniform loads were studied by using finite element method.Considering the reasonable ranges of design parameters of flat steel box girder, the influences of some parameters including the width and height of cross section, the thicknesses of top and bottom slabs, the thicknesses and spacings of longitudinal and transverse diaphragms on shear lag effects were analyzed.Based on the result of theoretical analysis, the practical formula was proposed to calculate the shear lag coefficient of flat steel box girder by using mathematical regression analysis, and the calculation result of practical formula was compared with the result of finite element method.Analysis result indicates that span-width ratio has the most significant influence on shear lag effects, when the span-width ratio increases from 1.786 to 8.926, the shear lag coefficients of top and bottom slabs decrease from 1.40 and1.32 to 1.07 and 1.06, and decrease by about 20%.When the thickness of longitudinal diaphragm increases from 10 mm to 30 mm, the shear lag coefficient of side web decrease by 7%, while the coefficients at other positions change by less than 1%.When the ratio of longitudinal diaphragm spacing to girder width increases from 0.430 to 0.582, the shear lag coefficient increases by 9%.Other parameters have negligible effect on shear lag coefficient.The relative error between the results of proposed practical formula and finite element method is less than1%, which conforms the formula has higher calculation precision, and meets the need of engineering calculation.