变截面连续箱梁桥恒载剪应力空间分布施工全过程分析  

Shear Stress Evolution with Construction Stage for Continuous Beam Bridge with Variable Box Girder Section

作　　者：杨一帆 惠迎新 杨建喜[1] YANG Yifan;HUI Yingxin;YANG Jianxi(School of Civil Engineering,Chongqing Jiaotong University,Chongqing 400074,China;Ningxia Engineering Research Center for Road Maintenance,Yinchuan 750004,China)

机构地区：[1]重庆交通大学土木工程学院,重庆400074 [2]宁夏道路养护工程技术研究中心,宁夏银川750004

出　　处：《土木工程与管理学报》2021年第6期170-177,共8页Journal of Civil Engineering and Management

基　　金：国家自然科学基金(51878106);重庆市自然科学基金(cstc2019jcyj-msxmX0818);重庆市科技创新领军人才项目(CSTCKJCXLJRC17);宁夏交通运输厅科技开发推广项目(201800172)。

摘　　要：针对空间梁单元模型无法准确计算薄壁箱梁剪应力的问题,利用ANSYS软件建立了考虑施工过程(恒载作用下)的多尺度有限元模型,采用应力积分方法获取控制截面内力并对比Midas/Civil杆系模型中对应阶段的内力结果,验证了耦合模型的正确性,分析了箱梁剪应力纵向、横向和竖向分布随施工阶段推进的演化规律,引入剪力贡献比分截面区域深入探究了各施工阶段下剪力分布情况。研究发现:恒载作用下,顶、底板竖向剪应力在顶腹板交接处大于其他位置,腹板竖向剪应力在竖向呈现多段折线式分布特征,且截面竖向剪应力分布模式在形成最大悬臂后,随施工过程的推进不明显;顶板竖向剪应力峰值在剪跨区内变化不明显,超过3/8截面后将线性减小;底板竖向剪应力峰值在剪跨区内近线性变化,超过3/8截面后将迅速减小;顶、底板水平剪应力沿横向分布时呈反对称形式;箱梁腹板承担了截面70%~80%的竖向剪力,当截面位置由支点向跨中靠近时顶板承担的竖向剪力份额将逐渐增大,底板份额将逐渐减小。Aiming at the problem that the spatial beam element model can not accurately calculate the shear stress of thin-walled box girder,a multi-scale finite element model considering the construction process(dead load)is established by using ANSYS software.The internal force of the control section is obtained by using the stress integral method.The correctness of the coupling model is verified by comparing the internal force results of the MIDAS/Civil bar system model in the corresponding stage,and the longitudinal shear stress of the box girder is analyzed.According to the evolution law of vertical,horizontal and vertical distribution with the progress of the construction stage,the shear contribution ratio section area is introduced to explore the shear distribution in each construction stage.The results show that:under the action of dead load,the vertical shear stress of the top and bottom plate at the junction of the top and web is greater than other positions,the vertical shear stress of the web presents the characteristics of multi segment broken line distribution in the vertical,and the vertical shear stress distribution mode of the section is not obvious with the progress of the construction process after the formation of the maximum cantilever;the peak value of the vertical shear stress of the top plate does not change significantly in the shear span area,and will decrease when it exceeds 3/8 section;the vertical shear stress peak value of the bottom plate changes nearly linearly in the shear span area,and decreases rapidly when it exceeds 3/8 section;the horizontal shear stress distribution of the top and bottom plate is antisymmetric along the transverse direction;the box girder web bears 70%~80%of the vertical shear force of the section,and when the section position is close to the middle of the span from the fulcrum,the vertical shear force share of the top plate will gradually increase,and the bottom plate share will gradually decrease.

关 键 词：桥梁工程 薄壁箱梁 剪应力分布规律 应力积分 剪力贡献比 

分 类 号：U441[建筑科学—桥梁与隧道工程]