钢筋混凝土构件锈蚀开裂与锈胀力分析

为合理确定锈胀力大小及其变化规律,研究混凝土保护层在锈胀作用下的开裂过程,提高混凝土结构使用寿命. 在考虑混凝土材料受拉软化和损伤效应的基础上,通过改变保护层厚度、钢筋直径、混凝土强度等参数,对钢筋锈胀引起的混凝土开裂过程、锈胀力分布和变化过程进行了有限元模拟和分析. 结果表明:均匀锈蚀下钢筋圆周上各处锈胀力分布并不均匀,明显受到内部裂缝的影响；锈胀力在裂缝贯通前达到峰值,之后快速下降最终保持稳定；保护层厚度c和钢筋直径d对锈胀的影响为线性关系,且统一用c/d值表征这两个参数是合理的,c/d值越大保护层完全开裂时的锈胀力和锈蚀率也越大,即延缓了保护层开裂. 基于锈胀力与c/d值的变化关系提出了最大锈胀力公式,并通过试验数据比对验证了最大锈胀力公式的有效性与精度. 

Investigation on corrosion-induced cracking and corrosion expansive pressure in reinforced concrete members

This paper aims to determine the corrosion expansive pressure and its change rule, study the process of concrete cover cracking under corrosion expansive pressure, and improve the service life of concrete structure. Considering the concrete strain softening and concrete damage, finite element simulation and analysis of the process of concrete cracking caused by rebar corrosion and the distribution and variation of corrosion expansive pressure were carried out by changing the parameters such as cover thickness, diameter of steel bar, and concrete strength. Results show that the expansive pressure of uniform corroded steel bar was nonuniform, which was influenced by crack. The expansive pressure reached its peak before the crack penetrated the cover, then it decreased quickly, and finally remained stable. The influence of cover thickness c and bar diameter d on expansive pressure was linear, and parameters c and d could be described with a unified c/d value. Furthermore, the larger the c/d value was, the larger the expansive pressure and corrosion rate were, which means the concrete cover cracking was delayed. Finally, a simplified formula was proposed to estimate the maximum expansive pressure, and the validity and precision of the formula were validated by experimental data.