钢筋锈胀引发混凝土保护层开裂破坏的细观数值研究

Meso-scale numerical study on cracking of concrete cover due to steel reinforcement corrosion

钢筋锈蚀膨胀引起保护层混凝土开裂是影响钢筋混凝土结构耐久性和服役寿命的重要因素。考虑到混凝土细观结构组成对保护层破坏模式的影响,从细观角度出发,将混凝土看作由骨料、砂浆基质及两者间界面过渡区组成的三相复合材料,建立了描述钢筋锈胀力学行为的混凝土随机骨料模型。采用塑性损伤本构关系模型来表征砂浆基质和过渡区界面的力学行为,假定钢筋均匀锈蚀,对钢筋锈胀引起的混凝土保护层开裂破坏过程进行了细观数值研究。对比了宏观均匀模型与细观非均质模型下获得的保护层破坏模式,探讨了径厚比(c/d)、钢筋位置(中部和角区)及混凝土拉伸强度对保护层破坏模式及保护层胀裂时钢筋锈蚀水平的影响,得到了一些有益结论。

Concrete cover cracking induced by corrosion of steel reinforcement is a major influencing factor for durability and service-ability of reinforced concrete （RC） structures. Here in the study,the influence of concrete meso-structure on the failure pattern of concrete cover is accounted for. At the meso-scale, the concrete is assumed to be a three-phase composite composed of aggregate, mortar matrix and the interfacial transition zone （ITZ）. A random aggregate structure of concrete is established for the study on the mechanical behavior of cover subjected to corrosion expansion of steel reinforcement. In the simulations,the plasticity damaged model is used to describe the mechanical behavior of the mortar matrix and the ITZ,and it is assumed that the corrosion of steel reinforcement is uniform. Based on the above assumptions, the cracking of concrete cover due to steel reinforcement corrosion is numerically simulated. The failure patterns obtained from the macro-scale homogeneous model and the present meso-scale heterogeneous model are compared. The effects of the ratio of cover thickness and reinforce- ment diameter （i. e. c/d）, the position of the steel reinforcement （i. e. ,the middle and corner zones） and the concrete tensile strength on the steel corrosion level when the concrete cover cracks are investigated. Finally, some useful conclusions are drawn.