钢框架高等分析中考虑局部屈曲的子结构法

Substructure method considering local buckling in steel frame advanced analysis

将相对自由度概念引入三维实体等参数单元,得到了16结点相对自由度壳元的插值表达式,并基于更新拉格朗日构型的虚位移原理推导了该壳单元的刚度矩阵。在单元刚度矩阵形成以后采用子结构法对内部结点自由度进行聚缩,根据薄壁构件相关假定并考虑截面翘曲因素的影响,通过边界结点的位移协调条件把壳单元组装成每端7个自由度的薄壁梁-柱单元参与整体分析,可以考虑板件局部屈曲的影响;突破了传统分析的紧凑型截面限制,并通过算例证明了本文方法的精确度和有效性。

The concept of relative degrees-of-freedom is introduced into the isoparametric element, and the interpolation expressions of 16 nodes shell element with relative degrees-of-freedom are obtained. The element stiffness matrix is derived according to the increment virtual displacement princi the updated Lagrange configuration. After the formation of substructure＇s stiffness matrix pie based on the degrees- of-freedom of internal nodes are condensed. According to the Vlasov＇s premises, the thin-walled beamcolumn elements considering the cross-section warping effects with 7 degrees-of-freedom at each end are assembled from shell elements by way of displacement coordination of the boundary nodes to participate in the global analysis. The limitation of compact section to steel members can be abandoned through the consideration of local buckling. In this way, precise analysis to members could be realized by shell elements in the advanced analysis of steel frames. The accuracy and efficiency of the proposed analytical method are verified by numerical examples.