Study On The Time-varying Properties And Durability Of Existing RC Members Based On The Bayesian Method

Concrete structures are the most wide used project structures ininfrastructure construction. Due to the natural erosion of carbonation andchloride, reinforced concrete structures were rusted and their bearingcapacity declined, and the durability of concrete structures is reduced. Asfar as the current situation, many concrete structures home and abroadwere damaged because of the lack of durability. So, it is very significantto carry out the research of durability and remaining useful life inprediction of the concrete structures in order to prevent structural damageand extend its life. The research for durability of existing structures notonly provides a scientific basis for decision-making of maintenance andrepair and reinforcement of existing structures, but also will offers thetheoretical basis for the durability design of concrete structures.In this paper, the theory of fuzzy mathematics is used to determinethe probability distribution model of parameters of engineering structures, and combining Bayesian methods, it elicited the Fuzzy Bayesian methodswhich probability distribution was determined by small sample data. Onthe base of detection test, the material properties of random variabilityand statistical parameters of concrete structure are analyzed by theBayesian method. Based on the existing chloride ion diffusion theory,distribution of chloride concentration and diffusion coefficient of existingconcrete structures in chloride environment is researched. According tothe measured depth of carbonation, the durability of concrete members isanalyzed based on concrete carbonation depth. Besides, using theBayesian method, the calculating methods for the durability reliableindicators and estimating methods for the durability of residual life underchloride environment based on the carbonation depth and chloride ionerosion are also elicited.Based on the research above, the time-dependent updating model ofthe concrete structure's material properties can be established by one orseveral test for the material properties (such as the concrete carbonationdepth and so on) of existing structures and introducing of the Bayesianmethod. According to the Bayesian methods and the measured parametersof concrete materials, the reliability of existing concrete structures ormembers can be calculated, and the durability remaining useful life canbe predicted.