摘要
为指导氯离子侵蚀环境下预应力混凝土结构耐久性设计和寿命预测,基于Fick第二定律的混凝土中氯离子扩散方程与热传导方程的相似性,考虑物理或化学吸附、毛细吸收、预应力等多种机制和因素对氯离子在混凝土内传输的影响,对氯离子扩散系数进行了修正,采用ANSYS中热分析模块对氯离子在预应力混凝土结构中的扩散过程进行数值分析。通过与氯盐侵蚀环境混凝土中氯离子浓度试验值进行对比,证明该方法能有效预测氯盐侵蚀环境混凝土中氯离子浓度分布。采用该方法对现役近海预应力混凝土铁路桥梁氯盐侵蚀情况进行模拟,分析得出服役60年左右该预应力混凝土铁路桥梁达到结构耐久性极限状态。
In order to guide the durability design and life assessment of prestressed concrete structure in the chloride erosion environment, the chloride diffusion coefficient was modified. The modification was carried out, on the one hand, in accordance with the similarity between the chloride diffusion equation and the heat conduction equation of concrete based on Fick's Second Law, and on the other hand, with the consideration of the impact of a number of mechanisms and factors on the chloride diffusion in the concrete, including the physical and chemical absorption, capillary absorption and prestress. The thermal analysis modular in the ANSYS software was a- dopted to carry out numerical analysis of the chloride diffusion process in prestressed concrete structures. By doing the comparison of the calculated values and the test results of the chloride density in concrete in chloride erosion environment, the method was proved to be able to effec- tively predict the chloride density distribution in concrete in the chloride erosion environment. The method was also used to simulate the chloride erosion condition of existing prestressed con- crete railway bridges near the sea. The results of the analysis show that the durability of the structure of the presstressed concrete railway bridge which has been in service for about 60 years reaches the ultimate state of its durability.
出处
《世界桥梁》
北大核心
2013年第3期62-65,共4页
World Bridges
关键词
铁路桥梁
预应力混凝土结构
氯离子扩散系数
热传导方程
氯离子阈值
寿命预测
有限元法
railway bridge
prestressed concrete structure
chloride diffusion coefficient
heat conduction equation
threshold chloride density
life assessment
finite element method