锈蚀钢筋力学性能退化规律试验研究

Experimental study on the deterioration of mechanical properties of corroded steel bars

通过对模拟人工气候环境和恒电流加速锈蚀的钢筋混凝土构件破型所得的56根锈蚀钢筋进行拉伸试验,研究两种加速锈蚀方法对锈蚀钢筋力学性能的影响,分析比较不同锈蚀程度下钢筋的各项力学性能指标的变化,发现不同加速锈蚀方法下混凝土内钢筋锈蚀表面特征的不同对钢筋力学性能退化有一定影响,且随着锈蚀程度的增加,这种影响会变得越来越明显。比如应力-应变曲线将发生明显变化,钢筋的屈服点和应力峰值降低且对应的应变减小;屈服平台逐渐变短,强屈比变小;极限延伸率减小和弹性模量随锈蚀率增大逐渐变小;颈缩现象变得越不明显等。研究表明,采用人工气候环境加速试验方法可以有效模拟自然气候环境中不均匀锈蚀引起的钢筋力学性能的改变,并在试验结果分析基础上,建立与锈蚀率相关的钢筋本构关系模型,为老化混凝土结构加固设计时提供应用参考。

The effects of artificial climate acceleration and galvanostatic acceleration on the mechanical properties of corroded steel bars were studied by tension tests on 56 corroded steel bars that were from corroded reinforced concrete members under acceleration conditions. The changes of mechanical properties of steel bars under different corrosion extents were analyzed and compared, the results indicate that different corrosion surface characteristics of steels in concrete under different acceleration conditions have some effects on the deterioration of mechanical properties of steel bars, and the effects get more significant as the corrosion extent increases： the stress-straln curve will change significantly, the yield point and stress peak value of steels and their corresponding strains decrease, the yield point elongation gradually shortens, the ultimate-yielding strength ratio diminishes; ultimate extension rate diminishes and Young＇ s modulus gradually diminishes as corrosion rate increases, the necking phenomenon gets less evident, and so on. The study shows that the artificial climate acceleration corrosion method can effectively overcome the differences in mechanical properties of steels between uniform corrosion under galvanostatic acceleration condition and non-uniform corrosion under natural climate condition. Based on the experimental results, the constitutive relation model of corroded steel bars with corrosion rate was obtained, which could be considered as an reference for reinforcement design of aging concrete structures.