Reliability Based Assessment And Test Research Of Durability Of Reinforced Concrete Structures

It is widely concerned in durability of reinforced concrete structures. Some efforts have been made in reliability based assessment and test research of durability for reinforced concrete structures in this paper. The major contents are mainly summarized as follows:1. Statistic relationship between water/cement ratio and chloride diffusion coefficient was gained by experiment, based on which the influence of concrete cover, water/cement ratio and design reference period on structural reliability was discussed.2. There are two models provided to predict remaining service life. One is based on reliability theory, and the other is on both reliability theory and economic optimization. Corresponding assessment criterions for remaining service life of existing concrete structures were put forward. According to the characteristic of concrete structures, a method was suggested to calculate the reliability of existing concrete structures. Strategy of repair and reinforcement on existing concrete structures in remaining service life was analyzed.3. A method to analyze remaining fatigue life for existing concrete structures was proposed based on reliability theory, in which the number of critical fatigue cycles under a certain stress was taken as a random variable. With this method fatigue reliability and remaining fatigue life in different circumstances were studied. From the numerical example, it shows that this method is not only suitable to predict useful remaining fatigue life with predetermined reliability index but also convenient to calculate corresponding fatigue reliability value with existing or specified frequency of varying loads in a certain service time, which will be instructive for structures in use.4. Based on fuzzy characteristics in durability failure criterion of concrete structures durable life was estimated, in which process survival analysis method was considered with fuzzy theory and the contribution of statement of truncation data was taken into account.5. The time of carbonization from surface of concrete structure to surface of steel bar in concrete structure was taken as a durable limit. Random characteristic of the limit was analyzed, based on which reliability index of carbonization in different servicing time was calculated and many relevant factors were discussed in two examples.6. The durability of concrete structures resisting Chloride diffusion in different water cement ratio and different contents of fly ash and silica was analyzed and durable life was predicted based on the results of the test, which will be helpful to preparation of high performance concrete (HPC) as well as durability design and assessment of concrete structures.The research work was supported by National Natural Science Foundation of China (59878008) and Key Research and Development Project of China Harbor Construction Company (Group)[No. 274, 2001].