混凝土结构中氯离子扩散分析的精细积分法

针对混凝土结构中氯离子扩散分析有限元模型存在的问题,为了去除氯离子扩散场半无限大假设及其对计算精度的影响,利用误差函数确定了氯离子扩散场的补偿长度及补偿系数,进而利用精细积分技术研究建立了混凝土中氯离子扩散分析的精细积分有限元法,定义了氯离子扩散矩阵和氯离子分布矩阵,研究了集中分布矩阵和一致分布矩阵对计算结果的影响。算例分析结果表明,该方法计算结果与解析解之间吻合很好,能够有效提高有限元法分析混凝土中氯离子浓度分布和扩散过程的计算精度、计算效率及算法稳定性。

Precise integration method for analysis of chloride diffusion in concrete structure

The conventional finite element model does not consider the effect of semi-infinite assumption of diffusion field for chloride ion in concrete based on the Fick’s second law.This paper presents the finite element equations of chloride diffusion by means of the Variational Principle.The concept and expression of compensation length is defined alone with compensation coefficient for the finite element model based on the error function,so that the error caused by the semi-infinite assumption is eliminated.The precise integration technology is incorporated into the finite element model for chloride diffusion in concrete so as to improve the computational accuracy,efficiency and convergence of the FEM.The diffusion matrix and distribution matrix are defined for the FEM model.The lumped and consistent versions of distribution matrix are investigated respectively.Examples in the paper show that the proposed method yields results agreeing well with the closed form solution.