混凝土结构保护层开裂时钢筋的临界锈蚀率模型

Critical Corrosion Rate Model for Reinforcement During Cracking of Concrete Cover

基于弹性理论与Bazant理论模型,引入拉伸损伤的概念,对混凝土保护层内环向应力进行修正,建立了混凝土保护层开裂时的临界锈胀力与钢筋临界锈蚀率模型.考虑钢筋混凝土界面间隙及锈蚀产物在裂缝中的填充效应,探讨了完全弹性、Bazant理论模型与拉伸损伤3种不同的环向应力下,钢筋直径、保护层厚度、锈胀系数对临界锈蚀率的影响.结果表明:临界锈蚀率随钢筋直径的增大而减小,随保护层厚度、锈胀系数的增大而增大.弹性下的临界锈蚀率大于Bazant理论模型与拉伸损伤下的临界锈蚀率.最后,与Morinaga的基于试验的临界锈蚀率模型比对,验证了模型的合理性.

Based on the theory of elasticity and Bazant＇ s physical model, the loop stress in concrete cover was modified correspondingly by introducing the concept of tensile damage, and models of critical corrosion-expansion stress and reinforcement corrosion rate were built at the moment when the concrete cover began to crack. By considering the filling effect of corrosion products in clearance between reinforcement and concrete and in the cracks, focus was given on the influences of the reinforcement diameter, concrete cover thickness and corrosion-expansion coefficient on the critical corrosion rates under 3 different loop stress conditions. These 3 conditions are proposed as perfect elasticity, Bazant model and tensile damage hoop stress, respectively. The results show that the critical corrosion rate decreases with the increase of the bar diameter, and increases with the increase of concrete cover thickness and corrosion-expansion coefficient. The critical corrosion rate in perfect elasticity is higher than that in Bazant model and in tensile damage. Finally, by comparing with Morinaga＇ s models, the models introduced in this paper are proved to be reasonable.