基于有效刚度的空间框架结构几何非线性分析

摘要

A geometrical non-linear finite element analysis method is proposed based on the effective stiffness of the elements of the space reinforced concrete frame structure by modifying the local stiffness matrix of existing elastic finite element of 3D linkage with the bending moment-rotation relationship of element including axial forces,and a simplified approach for quantifying the initial axial force of the column is suggested.Comparison of the results obtained by the proposed method,Chinese code GB 50010-2010 and American code ACI 318-1 1 is carried out.The analytical results indicate that, generally,only twice iterations are needed for the proposed method to achieve the accuracy of engineering requirement,and unnecessary for iteration if the initial axial force estimated by the suggested simplified method is used.For regular frame structures,the outcomes of the proposed method are close to those of Chinese code and American code.For irregular frame structures,the outcomes of the proposed method are greater than those of the two codes.%利用考虑轴力影响的单元弯矩-转角关系，通过修改常规三维杆系弹性有限元的局部刚度矩阵，提出了空间钢筋混凝土框架结构基于有效刚度的几何非线性有限元分析方法，并提出了确定柱初始轴力的简化方法。将该方法计算结果与我国规范 GB 50010—2010和美国规范 ACI 318-11计算结果进行了比较，结果表明，采用该方法计算一般只需两次迭代即可得到满足工程精度要求的结果；如果采用简化方法近似确定的柱轴力，则不再进行迭代也能得到很高精度的结果。对于规则的框架结构，该方法计算结果与我国规范和美国规范的计算结果接近；对于不规则框架结构，该方法计算结果比我国规范和美国规范的计算结果大。