Authors: Ya Li Ma, Ai Lin Zhang
Abstract: Probability distribution law of corrosion initiation time of steel in concrete under chloride environment is discussed. Based on the Fick’s second law, by Monte Carlo, frequency distribution, distribution type and probability density is analyzed. The statistic parameters of the factors influencing the probability distribution of corrosion initiation time are studied and the expression for sensitivity analysis of corrosion initiation time is deduced. By sensitivity analysis can know, corrosion initiation time is found to be more sensitive to cover than the diffusion coefficient, and more sensitive to surface chloride concentration than the critical chloride level. The analysis of the paper perfects the methods of predicting the corrosion initiation time.
5632
Authors: Ya Li Ma, Ai Lin Zhang
Abstract: Probability analysis on the durable life of concrete structure under chloride environment is little known. Using the probability method based on the second Fick’s law, research work was carried out to investigate the distribution factors that may influence the durable life of concrete structures. Due to the deficiency of decisive method to predict durable life, A method——based on the regulated reliability index is proposed. The relationship between durable reliability index and the corrosion time is established. The paper takes the time when the durable reliability index falls below the stipulated index as the end of durable life. The proposed method of durable life about concrete structure under chloride erosion environment is improved.
410
Authors: Wei Hua Shi, Zhi Wu Yu, Ya Chuan Kuang, Cheng Bin He
Abstract: Time dependency of chloride transport has been studied and an improving chloride penetration model has been established. Based on reliability theory, a durability analysis model has been build up and sensitivity analysis of steel corrosion probability has been performed. The analytical results show that age factor, cover depth and diffusion coefficient are key influence factors for corrosion probability of steel bar. Furthermore, influences on corrosion probability of temperature and relative humidity are significant quietly and must be considered in practical engineering.
1843
Authors: Bin Hong, Lu Feng Yang, Zheng Chen, Qing Ming Jiang, Chun Yan Hu, Ran Li
Abstract: The stochastic model of chloride diffusion is the foundation of evaluating concrete structures’ reliability in marine environment. In this paper, the random field of chloride diffusion coefficient was described as a group of random variables by local average theory. The chloride distribution matrix, diffusion matrix and nodal concentration vector were expanded by using the Taylor series. The stochastic finite element method was developed, and the mean and standard deviation of the chloride distribution concentration were yielded by the presented method. A numerical example demonstrated the high precision of the stochastic finite element method presented, and the service life of concrete structures could be predicted by the method.
831
Authors: Wei Hua Shi, Zhi Wu Yu, Ya Chuan Kuang
Abstract: Time dependency of chloride transport has been studied and an improving model for predicting the apparent chloride diffusion coefficient has been proposed. A probabilistic-based durability analysis to estimate failure probability on the chloride ingress into concrete has been carried out. Results of the analysis demonstrate that the improving model in this paper is appropriate for long term service life prediction of concrete structures exposed to chloride containing environment.
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