Time-dependent Reliability Of Non-uniform Corroded RC Beams In Chloride Environment

Non-uniform corrosion of reinforcement in concrete members under chloride environment usually leads to degradation of structural performance,which seriously decreases the normal use and durability performance of coastal infrastructure.The reliability of non-uniform corroded reinforced concrete members is investigated,which is of great significance for the long-term safe service performance of coastal concrete members.Supported by the National Natural Science Foundation of China(No.51509084),the reliability of non-uniform corroded reinforced concrete beams under chloride environment was analyzed using a combination of theoretical and numerical simulation in this paper.The research details are as follows:1.A time-dependent model of the mechanical properties with non-uniform corroded steel bars was developed.The non-uniform coefficient R of the cross-sectional area of corroded bars was used to describe the non-uniform situation of reinforcement under chloride ions attack.A model of non-uniform corroded concrete flexural beam was built and numerically simulated.The numerical simulation results agreed well with the experimental results which verifies the validity and feasibility of using the minimum cross-sectional area to describe the mechanical properties of corroded steel bars.2.A resistance degradation time-dependent model of non-uniform corroded reinforced concrete beams was established.The time-dependent models of concrete strength,reinforcement area,and strength of concrete members under chloride environment was determined,which focus on the effect of non-uniform corroded steel bars.Based on the models,the resistance degradation time-dependent model of non-uniform corroded reinforced concrete beams under consideration of various factors was established.3.Reliability of non-uniform corroded reinforced concrete was analyzed by a selfprogrammed program.By using C# self-written program,various sampling methods were used to calculate the reliability of corroded reinforced concrete beams,such as check point method,Monte Carlo direct sampling method,important sampling method and Latin hypercube sampling method.The various sampling methods were comparative analyzed.4.The characteristic factors influence of the resistance model on the reliability of RC beams was analyzed.Based on the resistance degradation time-dependent model,different characteristic factors on the reliability were analyzed.The characteristic factors mainly include the influence of the diameter and the type of steel bars,the thickness of the concrete protective layer,the average corrosion rate,and the material strength coefficient of variation.The study showed that the diameter and the type of steel bars,concrete protective layer thickness and average corrosion rate have a greater influence on the reliability,while the material strength coefficient of variation has a smaller influence.The resistance degradation time-dependent model of concrete members with non-uniform corroded steel bars under chloride environment was developed in this paper,which can provide theoretical reference for durability analysis and life prediction of non-uniform corroded reinforced concrete beams under chloride environment.