Reliability Based Durable Life Prediction Of Reinforced Concrete Structures

At present, durability of concrete structures under chloride environment has become one of the problems widely concerned by the academic and engineer circles in civil engineering. Due to the ingress of chloride, reinforcements in concrete corrode, so the durability of structures declines gradually, which will destroy the carrying capacity and shorten the service life of structures. Therefore, after the structures have been used for years, it is a very important task to evaluate the performance of degraded structures in order to predict their residual service life according to the use condition, actual load information and external environment.Based on the current research achievements on durability under chloride environment, probability theory, structural reliability theory, concrete structures theory, neural network theory and structure dynamic theory are employed comprehensively in this dissertation. Some problems of durability of reinforced concrete structures under chloride environment were studied through the exploitation of experimental data, the rule of chloride ingress and steel bar corrosion, the performance of corroded member, and residual life prediction. The main issues and results in this dissertation are as follows:1,The probability method for the prediction of durable life based on the stipulated reliability index for concrete structures under chloride environment is presented in this dissertation. Then, probability prediction model of durable life is founded. Through discussing the probability characteristics of influencing factors, the law of durable reliability is analyzed, and the prediction method is validated by the experimental data. The probability model for the initial time of corrosion is founded; and the distribution type and the probability density function for the initial time of corrosion are obtained. The results show that the method proposed in this dissertation can calculate the durable life of reinforced concrete structures under chloride environment accurately. The work provided in this dissertation may perfect the prediction method for the durable life of concrete structures.2,The reliability analysis method of corroded steel evenly or locally was established. Based on the analysis of experimental data from actual engineering, corrosion distribution law of general corrosion was found to follow the lognormal distribution through K-S test, while the localized corrosion follows the extreme distribution of typeâ… . Moreover, the calculation method of reliability for corroded reinforcements was discussed, and the law of reliability with the aging of corroded steel bars was obtained. The probability distribution of the ratio of the maximum corrosion depth to the general corrosion depth was analyzed. Through K-S test, it was found that this ratio follows the normal distribution or the lognormal distribution, which constructs a relationship between the mean corrosion condition and the worst corrosion condition. The research results about the statistic law of corroded steel bar...