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针对薄壁箱梁剪力滞效应有限元计算单元自由度多,计算工作量大的的问题,提出一种考虑剪力滞效应的组合单元法。顶板采用平面板单元模拟,轴向位移插值函数取3次多项式;腹板及底板采用梁单元分析。为减少有限元分析的单元自由度数目,取顶板单元的节点位移参数为基本位移参数,腹板与底板的位移模式由顶板与腹板及腹板与底板的变形协调关系得到,最后通过变分原理得到组合单元的刚度矩阵。以一座实桥为工程背景,通过与有限元程序计算结果对比,得出此方法的计算精度较高,计算效率亦比较高。
Aiming at the problem that the finite element method of thin-walled box girder has many degrees of freedom in finite element calculation unit and large workload, a composite element method considering shear lag effect is proposed. The top plate is simulated by flat plate element, and the axial displacement interpolation function takes polynomial 3 times. The web and bottom plate are analyzed by beam element. In order to reduce the number of unit degrees of freedom in finite element analysis, take the node displacement parameter of roof unit as the basic displacement parameter, and the displacement pattern of web and base plate is obtained by the deformation coordination relationship between roof and web and web and base plate. Finally, The principle is to get the stiffness matrix of the combined elements. Taking a real bridge as the engineering background, the calculation accuracy of this method is higher and the calculation efficiency is higher by comparing with the finite element program.