薄壁箱梁几何特性对剪力滞效应的影响  

Influence of thin-walled box girder geometric characteristics on shear lag effect

作　　者：梁永永 张元海[1] LIANG Yongyong;ZHANG Yuanhai(School of Civil Engineering,Lanzhou Jiaotong University,Lanzhou,Gansu 730070,China)

机构地区：[1]兰州交通大学土木工程学院,甘肃兰州730070

出　　处：《公路交通科技》2025年第2期131-136,共6页Journal of Highway and Transportation Research and Development

基　　金：国家自然科学基金项目(51968040)。

摘　　要：【目标】为便于分析薄壁箱梁的剪力滞效应,提出一种能够直观反映箱形梁剪力滞效应的几何特性参数。【方法】选取剪力滞附加挠度作为广义位移,应用能量变分法建立控制微分方程并给出初参数解,推导出简支及悬臂箱梁作用竖向集中荷载和竖向均布荷载时截面剪力滞广义力矩的计算公式。结合已有文献中的数值算例,将求得的正应力与有限元软件ANSYS应力结果进行比较并详细分析了几何特性k对剪力滞效应的影响以及截面尺寸变化对参数k的影响规律。【结果】解析理论计算结果与ANSYS结果吻合良好;简支箱梁剪力滞广义力矩在竖向集中荷载作用截面出现峰值,而后向简支两端迅速衰减,只发生在荷载作用截面附近区域;剪力滞广义力矩随几何特性k的增大而减小,其中靠近外荷载作用截面的梁段区域以较快的速度衰减,衰减幅度随k值的增加缓慢降低;随着悬臂板相对宽度比逐渐增大,几何特性k呈先减小后增大再减小的变化趋势,相对宽度等于0.5时参数k出现最大值;几何特性k随顶板厚度的增大而增大,随梁高、腹板和底板厚度的增大而减小。选择壁厚较大的顶板与壁厚较小的腹板有助于减小箱梁的剪力滞效应。[Objective]To analyze the shear lag effect of thin-walled box girders,the geometric characteristic parameter was proposed,which could intuitively reflect the shear lag effect of box girders.[Method]The additional deflection due to shear lag was selected as the generalized displacement.The control differential equation was established by using the energy variation method.An initial parameter solution was provided.The calculation formulas for generalized shear lag moment of cross-sections were derived under vertical concentrated loads and vertical uniform distributed loads for simply-supported and cantilever box girders.By combining the numerical examples from existing literatures,the calculated normal stress was compared with the stress result with finite element software ANSYS.The detailed analysis was conducted on the influence of parameter k on shear lag effect,as well as the influence of cross-section dimension variation on parameter k.[Result]The theoretical analytical result is in good agreement with the ANSYS result.The generalized shear lag moment of simply-supported box girder exhibits a peak at the section under vertical concentrated load. Then the backward simply-supported ends decay rapidly. The effect occurs only at theregion near the loaded section. The generalized shear lag moment decreases with the increase of geometriccharacteristic k. The girder segment near the external load application section decays more rapidly. Thedecay amplitude decreases slowly with the increase of k value. As the relative width ratio of cantilever slabincreases gradually, the geometric characteristic k first decreases, then increases, and finally decreasesagain. When the relative width is 0. 5, the parameter k reaches its maximum value. The geometriccharacteristic k increases with the increase of top slab thickness, but decreases with the increase of beamheight, web thickness, and bottom plate thickness. Choosing the top slab with larger thickness and the webwith smaller thickness helps to reduce the shear lag effect of b

关 键 词：桥梁工程 剪力滞效应 能量变分法 薄壁箱梁 几何特性参数 

分 类 号：U448.213[建筑科学—桥梁与隧道工程]