钢筋混凝土构件非线性有限元分析

本文对原有的通用结构分析程序NONSAP进行了修改扩充,形成了单增荷载下钢筋混凝土构件的非线性有限元分析法.本方法对混凝土采用非线性正交平面等参单元,在材料模型中计入了拉裂、受拉强化、裂缝面上的剪力传递和压应变屈服等混凝土特性;对钢筋采用弹塑性三向连杆单元;引入三向非线性联结单元以模拟钢筋和混凝土之间的相互作用.数值计算采用初始刚度和切线刚度的合混型增量迭代法;在材料破坏时计入了不平衡力的重分配.本方法的计算结果和试验结果符合良好,表明了该程序的可用性.

NONLINEAR FINITE ELEMENT ANALYSIS FOR REINFORCED CONCRETE MEMBERS

Nonlinear FEH for reinforced concrete members under monotonically increasing loads is presented. An existing general structural analysis package NONSAP-1974 version is modified to include the following:2-D nonlinear orthotropic isoparametric elements to model the concrete, which consider compressive strain softening, tension cracking, tension stiffening, and interlock shear transfer; elastoplastic truss elements to model the reinforcement; and 3-D nonlinear linkage elements to represent steel-concrete interaction. The numerical algorithm is iteration method of incremental load steps with a combined initial stiffness and tangential stiffness formulation within the load step. Concrete cracking is accomplished by unbalanced force redistribution within the load step. Finite element calculations are compared with experimental results for an axially loaded tensile specimen and a reinforced concrete beam. The good correlation between the computational and experimental results shows the applicability of the present work.