基于组合单元的圆钢管混凝土结构非线性分析

基于圆钢管混凝土组合截面轴力-应变关系和轴力一弯矩一曲率关系实用计算方法,采用U.L列式单元增量平衡方程,引入平面梁单元非线性分析方法,建立了钢管混凝土结构组合单元法非线性有限元分析理论.编制了相应的非线性有限元程序,对已有钢管混凝土结构的面内受力,如钢管混凝土偏压柱、不等端弯矩钢管混凝土偏压柱、钢管混凝土压弯构件和钢管混凝土模型拱肋等进行双重非线性有限元分析,与基于钢管混凝土拉压数值本构模型的分层梁单元非线性分析理论比较.结果表明,两种分析方法的载荷一变形曲线和极限承载力都很接近试验结果,与分层法相比,组合单元法直接根据杆端力求解截面刚度,不用分层计算截面刚度,加快了计算速度.

Nonlinear finite element analysis of concrete filled circular steel tubular structures based on composite element method

The relationship of axial force-strain and axial force-moment-curvature for cross-section in concrete filled steel tubular(CFST)beam-columns is analyzed by practical calculation methods.The nonlinear finite element analysis of CFST structures by composite element method is proposed based on the U.L.formula of element incremental equilibrium and the nonlinear analysis of plane beam element.The method is used in the CFST structures subjected to in-plane load such as CFST columns under eccentric loading of equal end-moment and unequal end-moment,CFST beam-columns,and CFST arches.The data from calculated results are consistent with the data from layered finite element method;both data are verified by the experiments.Comparing with the layered finite element method,the composite element method removes the steps of calculating section stiffness based on layered finite element method while achieving similar results.