桥梁结构非线性实体有限元建模

桥梁研究中有一些特殊的分析,不仅需要考虑结构的非线性问题,而且要用实体单元模型计算关键点处的应力-应变状态。鉴于考虑非线性的实体有限元模型在桥梁工程中应用较少,为了提高计算模型的可靠性,分析和讨论了这种有限元模型构建过程中应该注意的若干问题,包括几何模型的选择、非线性本构关系的选择、边界条件的处理、荷载的施加、单元类型的选择和网格划分、非线性算法选择等。最后基于这些探讨,以一个钢-混组合梁为例,用非线性实体有限元法对其进行了承载能力极限状态的模拟,软件的输出数据与实验实测结果吻合较好,这证明了在一些特殊的桥梁结构分析中,采用考虑非线性的实体单元模拟是可行的。

Research on Nonlinear Solid Finite Element Modeling for Bridge Structure

Some special analysis of the structure of bridge not only needs to consider the nonlinear problems of the structure,but also needs to use solid finite element model （FEM） of the structure to calculate the stress-strain states at key points. In view of the fact that the nonlinear solid FEM is rarely applied in calculation or analysis of bridge, in order to improve the calculation reliability of this FEM,common problems in modeling procedure of nonlinear solid FEM for the structure of bridge are discussed. The discussions include model setup, selection of nonlinear constitutive relations, boundary conditions, loads, element select, mesh technique and solving method. Based on these discussions, an example of FEM of a steel-concrete composite beam simulated by nonlinear solid elements for the ultimate limit state analysis is introduced. The results of calculation of the nonlinear solid FEM fit with experimental results better, which indicate that the method of nonlinear solid FEM is effective for some special analysis of bridge structure.