分段施工钢箱梁桥最不利荷载效应作用下剪力滞效应分析

Shear Lag Effect under the Most Unfavorable Load Effect for Steel Box Girder Bridge in Segmented Construction

由于受箱梁剪力滞效应的影响,施工过程中采用初等梁理论计算得到的钢箱梁桥顶、底板的正应力不准确。文章应用Midas-Civil杆系有限元模型,计算得到钢箱梁桥纵向弯矩包络图,确定纵向最大正、负弯矩数值最大截面位置,以及最大正、负弯矩截面的弯矩影响线;进一步,应用Abaqus壳单元有限元模型,对最大正、负截面施加最不利车道荷载以及自重,并考虑车道荷载横向偏载,计算得到最不利加载截面的剪力滞系数。结果表明:在钢箱梁桥结构中,载横向偏心布置的条件下,纵向负弯矩最大截面顶板的剪力滞系数最大,最大值为1.812;在最大纵向正弯矩截面位置,在车道荷载横向偏心布置的条件下,钢箱梁底板的剪力滞系数最大,最大值为3.403。

Due to the shear lag effect for box girder,the calculated normal stress of the top and bottom plates is not accurate using the elementary beam theory during the construction process.In this paper,based on the beam element model of Midas-Civil,by calculating the longitudinal bending moment envelope diagram of the steel box girder bridge,the section position of the maximum longitudinal maximum positive and negative bending moment were determined,and the bending moment influence lines of the maximum positive and negative bending moment sections were determined.Furthermore,using the shell element model of Abaqus,the most unfavorable lane load and self weight were applied to the maximum positive and negative bending moment sections.Then,considering the lateral eccentricity of the lane load,the shear lag coefficients were obtained.The results show that:(1)For the steel box girder bridge structure,under the condition of lateral eccentricity load arrangement,the shear lag coefficient of the top plate for the maximum longitudinal negative bending moment was the highest,with a maximum value of 1.812.(2)At the position of the maximum longitudinal positive bending moment section and under the condition of lateral eccentric arrangement of lane loads,the shear lag coefficient of the bottom plate for the steel box girder is the highest,with a maximum value of 3.403.