薄壁直线箱梁仿真分析的板段元方法

针对现有计算方法无法准确反应箱梁断面框架受力特征的缺陷,提出一种新的板段单元分析法。该方法基于Kirchhoff直线法假设,在已有箱梁腹板、翼板刚度方程基础上,准确考虑横隔板对结构整体受力的影响,相对粗略考虑横隔板自身的应力变化规律,提出新的横隔板元位移模式,从而建立完整的箱梁板元分析列式。算例分析表明:该方法可正确模拟箱梁纵向正应力受横隔板的影响规律,即较好地反映横隔板对箱梁翼、腹板的弹性支承效应;与通用有限元精细模型相比,在相同的计算精度要求下,板段元法所需的自由度少得多,极大地降低了仿真分析的计算量。板段元法适用于其他断面形状的箱梁结构或肋板式结构,也可用于斜交箱形直梁的分析,具有较好的适用性。

Deck Beam Finite Element Method for the Simulation Analysis of Thin-Wall Linear Box Girder

For the deficiencies of existing method for reflecting the mechanical behaviors of box girder cross-section,a new deck beam finite element analysis method is proposed.This method is based on the presupposition of Kirchhoff.According to the existing stiffness equations of box girder wing and web,a new displacement function for diaphragm plates of the box girder is proposed,which could result in higher precision of diaphragm plates influence on box girder despite the stress precision of itself not being improved.Thus a new deck beam finite element analysis method for linear box girder is formulated.The result of a numerical example shows that this method can correctly simulate the influence on the longitudinal normal stress of the box girder by diaphragm plate.Namely,it can better reflect the elastic supporting effect of diaphragm on box girder wing and web.Compared with other general finite element precise models,deck beam finite element analysis method achieves similar precision with much fewer freedom degrees.Thus it can decrease greatly the work of simulation analysis of box girder.Besides these,deck beam finite element analysis method can be applied flexibly to box girders with different cross-section or rib-plank structure and those without orthogonal support.