摘要
同时考虑薄壁箱梁截面的弯曲挠度、剪切挠度和剪力滞附加挠度,利用变分法对箱梁的剪力滞效应进行了分析。在构造剪力滞翘曲位移函数时,考虑翘曲应力中性轴对于截面形心轴的偏移,利用截面翘曲应力合力及合力矩均应为零的平衡条件,建立控制微分方程。分别针对简支梁在均布荷载及跨内集中力作用下的剪力滞效应,推导出翘曲应力和附加挠度计算公式。变分法分析过程表明初等梁理论下的弯曲、剪切效应与剪力滞效应相互解耦。以简支梁模型为算例,利用论文方法计算的截面应力值与有限元解及实测值吻合良好,验证了论文方法的合理性。利用不同几何参数分析是否考虑翘曲应力中性轴的偏移产生的应力差别。结果表明:对于截面应力,高宽比的影响较小,宽跨比影响较大,宽跨比>0.2时,相对应力差值超过20%。
In this paper,considering the bending deflection,shear deflection and shear lag additional deflection of the thin-walled box girder section,the shear-lag effect of the box girder is analyzed by the variational method.The transverse warping displacement function and controlling differential equation are built considering the offset of the warping stress neutral axis to the centroidal axis of the section in order to satisfy the equilibrium condition of resultant force and moment of warping stress on the section.The formulas of warping stress and additional deflection are derived for the shear-lag effect of simply supported beam under uniform load and concentrated force in span.The process of variational analysis shows that the bending,shear effects under the elementary beam theory and shear-lag effect are decoupled one another.Taking the simply supported beam model as an example,the section stress calculated by this method is in good agreement with the finite element solution and the measured value,which verifies the rationality of this method.Different geometrical parameters are used to analyze the difference of stress caused by the deviation of neutral axis of warping stress.The results show that:for the section stress,the influence of the ratio of height to width is small,and the influence of the ratio of width to span is large.When the ratio of width to span is larger than 0.2,the relative stress difference is more than 20%.
作者
杨青山
刘世忠
周倩
YANG Qingshan;LIU Shizhong;ZHOU Qian(School of Civil Engineering,Lanzhou Jiaotong University,Lanzhou Gansu 730070,China;Qingyang Architectural Design Institute of Gansu,Qingyang Gansu 745000,China)
出处
《工程质量》
2021年第5期39-43,共5页
Construction Quality
基金
国家自然科学基金项目(51868040,51708269)。
关键词
薄壁箱梁
剪力滞效应
翘曲应力平衡
中性轴偏移
能量变分法
thin-walled box girder
shear-lag effect
warping stress balance
neutral axis offset
energy variational method
