Study On The JC Method And Its Application On The Reliability Of Bridges

As the pivot project of transportation system, bridge structure occupies a special position and plays a decisive role in the national economy and social life. Bridge security is related to everyone’s life. Because of the influence of bridge material and ambient environment and other factors, the performance of the reinforced concrete structure is deteriorating, which may cause potential severe security issues. How to evaluate the bridge durability effectively is an urgent, important and meaningful task now.On the basis of previous theories and existing researches, this dissertation improves the extant chloridion diffusion model algorithm, discusses the mechanism of bridge deterioration on the foundation of reliability theory and learns and researches the reliability evaluation and lifetime prediction of reinforced concrete bridge structure.First, this article learns and discusses the evaluation method and developing trend of bridge durability, introduces the applicability, strengths and weaknesses of all kinds of bridge durability methods and figures out the advantages of reliability theory about the evaluation of bridge durability. In Chapter II, this paper gives a systematic introduction of the basic mechanism and algorithm of bridge structure reliability and makes some preparation of the measurement of bridge structure reliability and lifetime prediction.Second, due to the chlorine corrosion, the durability of concrete bridge is damaged severely. In Chapter III, this dissertation makes a detailed explanation of the mechanism and developing procedure of the reinforced concrete damage caused by chloride erosion. On the foundation of existing theories, this paper introduces the amended chloridion diffusion model that is based on the load influence, polymerizing power of chloridion and environment(temperature and moisture). Compared to the traditional model that only takes single factor into consideration, the new one is more reasonable and accurate chloridion diffusion model amends the existing rebar corrosion model and makes the comparison between these two models.At last, based on the improved rebar corrosion model, this article describe the JC method in detail, and do a comparison with an an improved JC method. It obtained its good applicability, to ensure accuracy, but also has a good convergence, gets the reliability and failure probability of the bridge structure, figures out the left time of the bridge with the JC algorithm and realizes it by using MATLAB.