【摘要】 在考虑材料非线性和几何非线性的基础上进行了钢管混凝土柱-钢梁平面框架结构力学性能的非线性有限元分析,核心混凝土采用考虑钢管约束效应的应力-应变关系,钢材采用二次塑流模型或线性强化模型,通过在有限元公式中引入几何刚度矩阵,并在荷载步中更新坐标描述二阶效应来反映框架结构的几何非线性效应。基于近似修正的拉格朗日表述来反映框架结构变形前后位形之间的关系,利用虚功原理建立相应的增量平衡方程,并采用位移增量法求解非线性有限元方程,理论计算结果得到试验结果的验证。分析表明,基于非线性纤维梁-柱单元理论的分析方法可以反映钢管混凝土框架在受力过程中构件屈服和塑性分别沿截面和杆长两个方向扩展的分布塑性特征,并考虑初始缺陷、残余应力等,因此可较好地反映钢管混凝土框架的力学性能。在此基础上对影响钢管混凝土框架力学性能的主要因素进行了参数分析,分析的具体结果可供有关研究或工程应用参考。更多还原

【Abstract】 The nonlinear finite element analysis(FEA) on mechanical behaviour of composite frame which composed of concrete filled steel tubular(CFST) columns and steel beam under sustaining axial load and lateral loads was carried out.The material and geometric nonlinearities were considered.The stress-strain relationship of core concrete was given under confinement effect by the outside steel tubes.The stress-strain curves was second-order elastic-plastic model or linear aggrandizement model.The geometric stiffness matrix and updated coordinate strategy were adopted to describe the geometric nonlinearity of the frame.The relationship between displacements of the CFST frame before and after deformation was based on Approximate Updated Lagrange(AUL) description.The increment equilibrium equations were found on virtual work principle.The nonlinear equations were solved by displacement increment method.The calculated results agree well with the tested results.The results show that the finite element analysis based on fiber beam-column elements was reasonable to predict the performance of CFST frames because the method can consider the yield and plastic extending within the sections and along the elements.The initial imperfect and residual stress can be included too.Parametric study was performed based on the FEA model and some useful conclusions were obtained for correlative researcher and designer.更多还原