混凝土构件中钢筋非均匀锈胀力研究

Research on Non-uniform Corrosion Expansion Stress of Reinforcing Bars in Concrete Members

研究钢筋锈蚀引起混凝土保护层开裂的机理,对于评估受锈蚀影响的混凝土结构剩余寿命具有重要意义.论文提出了一种求解钢筋非均匀锈蚀应力场的解析方法.基于Muskhelishvili的复变函数法和Verruijt共形映射公式,利用基于冯·米塞斯分布的钢筋非均匀锈蚀模型作为位移边界条件,得到了钢筋非均匀锈胀应力的解析解,所得结果与ANSYS有限元模拟结果一致.研究表明:非均匀锈蚀引起的最大锈胀力远大于均匀锈蚀引起的最大锈胀力;钢筋直径越大,锈胀力越小,混凝土保护层越容易开裂;混凝土保护层厚度越大,锈胀力越大;混凝土强度等级越高,钢筋锈胀力亦越大.

Concrete cover cracking induced by rebar corrosion has a considerable effect on the durability and serviceability of reinforced concrete structures. Therefore, the cracking mechanism of concrete cover caused by rebar corrosion is of great significance for evaluating the residual life of concrete structures. In the past, lots of studies have been conducted on the corrosion-induced concrete cracking based on uniform corrosion. In the real case, however, the rebar-corrosion products normally accumulate at the bar surface facing the concrete cover, which results in non-uniform corrosion. This study proposes an analytical method for solving the non-uniform corrosion stress field of rebar. First, the problem of rust expansion cracking of the concrete cover is simplified as an elastic half-plane problem with circular holes. Then, based on Muskhelishvili’s complex variable function and Verruijt’s conformal mapping formula, the elastic half-plane is mapped into a ring region. Finally, the analytical solution of reinforcement’s non-uniform expansion stress is obtained by using the non-uniform corrosion model acquired by the von Mises distribution as the boundary condition for displacement. The effectiveness of the analytical solution is verified by comparing with the simulation results based on ANSYS. A comparison between the stresses induced by non-uniform corrosion and uniform corrosion indicates that the maximum rusting stress caused by non-uniform corrosion is much larger than that caused by uniform corrosion. Furthermore, several factors affecting the non-uniform corrosion expansion stress are discussed by real examples in this study, and the results show that the larger is the rebar diameter, the smaller is the corrosion expansion stress, and the easier it is for the concrete cover to crack. In addition, the corrosion expansion stress increases with the thickness of concrete cover and the strength grade of concrete. This study provides a scientific basis for the structural design of reinforced concrete which is susceptible to corrosion.