关键词: 混凝土耐久性;可靠度指标;耦合作用;氯离子扩散

Abstract: Based on the ratio of bending moment to flexural capacity as load level index, diffusion behavior of chloride ion in reinforced concrete under bending moment was studied.The function relationship between load level and chloride ion diffusion coefficient was established.Then the limit state equation and the calculation method of the corresponding durability reliability considering the concentration of chloride ions on the surface of rebar under load were proposed.The corrosion probability of reinforcement under different load levels in splash zone was calculated by this new method based on provided calculation examples.The calculation results show that the difference of durability reliability index could be more than 100%between considering the loading effect and not considering it,reflecting the significant effect of loading on reliability index β.Based on the durability requirement of concrete beams,some revision suggestion is provided:It is recommended that for beams with the relevant design life of 30 years, 50 years and 100 years in splash zone, the corresponding minimum protective layer thickness should be improved to 60 mm, 65 mm and 75 mm respectively, and the corresponding maximum water-cement ratio limit should be controlled to be 0.36.

Key words: concrete durability;reliability index;coupling effect;chloride ion diffusion