双向偏压钢筋混凝土柱的有限元分析模型

为实现钢筋混凝土柱的高效精确分析，建立了基于纤维积分法的可用于任意截面双向偏压钢
筋混凝土柱材料和几何非线性分析的有限元模型。基于混凝土和钢筋的非线性应力-应变关系，引入
Rodriguez截面分析模型，按边界顶点把混凝土截面划分成若干个梯形单元，通过对纤维直接积分导出截
面切线刚度矩阵，并基于空间非线性杆单元理论建立标准有限元公式。利用该分析模型对双向偏心受压钢
筋混凝土试验柱进行极限承载力分析计算，结果表明所提出的有限元模型具有较高的计算精度；通过采用
纤维积分法来替代传统的截面分块或分条法，显著提高了计算效率。

Finite element analysis model for reinforced concrete columns subjected to biaxial eccentric compression

To analyze reinforced concrete columns efficiently and accurately, a finite element model based on the fiber integration method for the material and geometrical nonlinear analysis of reinforced concrete columns with arbitrary section under biaxial eccentric compression was developed. On the basis of nonlinear stress-strain relationships of concrete and reinforced steel, a section analytical model suggested by Rodriguez was introduced to derive the section tangent stiffness matrix by directly integrating the trapezoids divided from the concrete section according to boundary vertices. The standard finite element formulae were established utilizing the nonlinear spatial frame element theory. The proposed model was used to calculate the ultimate load-carrying capacity of the reinforced concrete test columns subjected to biaxial eccentric compression. Analytical results show that the proposed model has higher computational precision, and that by adopting the fiber integration method instead of the conventional strip or square method, computational efficiency is improved notably.