| 摘要: |
| 鉴于海洋混凝土结构的材料特性及环境因素具有随机性和时变性，在混凝土的氯离子扩散模型中引入氯离子扩散系数和表面氯离子浓度时变函数.采用高斯随机场描述混凝土的氯离子扩散系数的随机特性，然后在以局部平均法离散该随机场的基础上，研究建立了混凝土中氯离子随机时变扩散分析的摄动随机有限元法（SFEM），并推导了氯离子浓度均值和协方差的计算表达式.通过与试验值和Monte Carlo有限元法（MCFEM）的比较，验证了SFEM具有较高的计算效率和精度.算例分析表明：氯离子扩散系数的随机时变性对混凝土中氯离子扩散过程具有显著影响；对于长期服役的混凝土结构，混凝土表面氯离子浓度时变性对氯离子扩散过程的影响可以忽略. |
| 关键词: 时变 随机有限元 混凝土 氯离子扩散系数 表面氯离子浓度 |
| DOI：10.3969/j.issn.1007 9629.2013.02.005 |
| 分类号: |
| 基金项目:国家自然科学基金资助项目（51168003）；广西壮族自治区主席基金资助项目（2010GXNSFD169008）；广西自然科学基金资助项目（2011GXNSFB018013） |
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| Stochastic and Time Dependent Diffusion of Chloride Ionin Concrete and Its Concentration Distribution |
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YANG Lü feng, HU Chun yan, CHEN Zheng, HONG Bin
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Key Laboratory of Disaster Prevention and Structural Safety of China Ministry of Education, Guangxi University,Nanning 530004, China
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| Abstract: |
| As the material performance and environment of marine concrete structures are random and time dependent, the perturbation stochastic finite element method（SFEM） for analysis of chloride ion diffusion in concrete, incorporating the time dependence into the mathematical model of chloride ion diffusion coefficient and surface chloride ion concentration was proposed. The Gaussian random field was used to model the chloride ion diffusion coefficient of concrete, while the local average method was employed to discretize the random field. According to the variational principle and the perturbation technique, the governing equations for the SFEM were presented, by which the mean value and covariance of chloride ion concentration could be determined. Comparing with test result and Monte Carlo finite element method（MCFEM）, the efficiency and accuracy of the presented method is demonstrated. It can be concluded that the random and time dependent chloride ion diffusion coefficient can significantly influence the process of chloride ion diffusion in concrete, while the effect of the time dependence of surface chloride ion concentration can be neglected for concrete structures exposed to chloride environment for a long term duration. |
| Key words: time dependence stochastic finite element concrete chloride ion diffusion coefficient surface chloride ion concentration |
