钢筋混凝土结构的钢筋锈胀引起的保护层开裂研究（英文）

Cover cracking model in reinforced concrete structures subject to rebar corrosion

研究目的:预测保护层开裂的时间以及分析锈胀参数研究方法:基于混凝土的各向异性损伤,建立考虑钢筋–腐蚀产物–混凝土三者不同力学性能的钢筋锈胀导致保护层开裂的数学模型。模型考虑了腐蚀产物对钢筋混凝土界面区的孔隙和混凝土开裂裂缝的填充效应,采用了非线性分析算法,预测了开裂过程中每一时刻混凝土构件的应变与位移场以及混凝土保护层开裂时间,最后将模型预测值与试验值进行对比。重要结论:1.当混凝土出现裂缝之后,随着腐蚀产物对裂缝的填充,混凝土的环向拉应变的增长速率减缓;2.选定钢筋的型号、直径以及混凝土的强度之后,可通过增大保护层的厚度来减小钢筋锈胀开裂的风险。

A new cover cracking model is proposed for rebar corrosion. Rebar corrosion involves rust, which contributes to an expansive radial pressure at the concrete-steel interface and hoop tensile stresses in the surrounding concrete. Once the stress state exceeds a certain limit, anisotropic damage occurs. First, we establish an anisotropic damage model for concrete, which fully reflects the unilateral effect. Then an analytical model is proposed to calculate the displacement and the stress in a corroded re- inforced concrete （RC） structural member based on that anisotropic damage. In this study, a concrete-rust-steel composite model is considered as a circular cylindrical concrete cover and a coaxial, uniformly-corroded, steel rebar, where the steel rebar and the mechanical properties of rust can be fully taken into account. At the same time, the influences of the steel-concrete interface pores and the cracks in concrete on the rust expansion pressure value are modeled. Finally, some experiments are made for comparison with the analytical results and good agreement indicated the proposed model could be used to predict both the variation of strain fields in structures during the corrosion process and the cover cracking time.