偏载作用下超宽幅分体钢箱梁扭转效应分析

Torsional Effect of Very Wide Split Steel Box Girder Subject to Eccentric Loads

为研究不同成桥偏载作用下宽幅分体钢箱梁的扭转效应及结构参数对扭转效应的影响规律,以西堠门公铁两用大桥主桥斜拉-悬索协作区段宽幅分体钢箱梁为背景进行有限元分析。该桥为主跨1488 m的斜拉-悬索协作体系桥,主梁为由3个流线型扁平钢箱通过箱形横梁连接组成的超宽幅分体钢箱梁。采用Abaqus软件建立该桥斜拉-悬索协作区段宽幅分体钢箱梁精细化有限元模型,计算3种偏载工况作用下钢箱梁3个典型截面(吊索作用截面、无横梁连接截面、斜拉索作用截面)顶、底板扭转翘曲正应力;分析腹板厚度、横梁宽度以及吊索横向间距对宽幅分体钢箱梁扭转效应的影响。结果表明:3种偏载工况作用下宽幅分体钢箱梁扭转效应明显,其中无横梁连接截面扭转效应最为突出,设计时应予以关注;增大腹板厚度可以降低钢箱梁顶、底板扭转效应,增大横梁宽度会增大顶板、腹板中间位置附近的扭转翘曲正应力,但会降低底板的扭转翘曲正应力最大值;吊索横向间距对扭转效应影响较小。

In this paper,the torsional effect as well as the influences of structural parameters on the torsional effect of the wide split steel box girder under eccentric loads after the completion of the bridge are studied.The main bridge of Xihoumen Rail-cum-Road Bridge is used as a case,which is a combined cable-stayed and suspension structure with a main span of 1488 m and the stiffening girder consists of three lateral streamlined flat steel boxes.The torsional warping normal stresses in the top and bottom plates of three typical cross-sections of the steel box girders under three types of eccentric loads were numerically simulated in Abaqus,including the cross-section suspended by hanger cables,cross-section without cross beams and the cross-section supported by stay cables.The influences of multiple parameters on the torsional effect of the wide split steel box girder are analyzed,including the web thickness,cross beam width and the transverse spacing of hanger cables.It is shown that the torsional effect of the split steel box girder under three eccentric loads is significant,and the torsional effect on the cross-section without cross beams is the greatest,which should be given special concern in design.To increase the web thickness can improve the torsional effects in the top and bottom plates of the steel box girder,while to enlarge the width of the cross beams intensifies the torsional warping normal stress in the vicinity of the center of the web,but suppresses the maximum torsional warping normal stress in the bottom plates.The transverse spacing of hanger cables exerts minor influence on the torstional influence.