锈蚀钢筋横截面积分布规律统计分析

检测确定钢筋的锈蚀特征参数是进行锈蚀钢筋混凝土结构性能评定的基础。通过电化学加速锈蚀试验获得不同锈蚀程度的钢筋,采用三维激光扫描技术建立锈蚀钢筋的三维几何模型,并提取相关的锈蚀特征参数。然后基于概率理论统计分析锈蚀钢筋平均截面锈蚀率与最大截面锈蚀率、锈蚀不均匀系数之间的相关性,建立了锈蚀不均匀系数的概率分布模型。研究表明:随着锈蚀程度的增大,最大截面锈蚀率和锈蚀不均匀系数均呈幂函数增长,并与锈蚀钢筋的直径有关;锈蚀不均匀系数服从广义极值分布,其概率分布的形状参数、尺度参数和位置参数均随锈蚀程度的增大而线性增大,并与锈蚀钢筋的直径和单元长度有关。

Statistical analysis of cross-sectional area distribution law of corroded reinforcing steel bars

The detection and evaluation of the corrosion characteristic parameters of steel bars is the basis for the performance evaluation of corroded reinforced concrete structures. The corroded steel bars with different target corrosion degrees were obtained by electrochemical accelerated corrosion test. Three-dimensional laser scanning technology was adapted to establish 3D geometric models of corroded steel bars, and the relevant corrosion characteristic parameters were extracted. Then the relationship between the average and maximum cross-sectional area loss ratio, as well as the corrosion non-uniformity coefficient were analyzed based on the probability theory. The probability distribution model of corrosion non-uniformity coefficient was also established. The results show that with the increase of average cross-sectional area loss ratio, both the maximum cross-sectional area loss ratio and the corrosion non-uniform coefficient increase as power function, and the parameters of power function are dependent on the diameter of the corroded steel bar. The corrosion non-uniform coefficient could be characterized by the generalized extreme value distribution. The shape, scale, and location parameters of the probability distribution increase linearly with the increase of corrosion degree, which are also dependent on the element length and the diameter of the corroded steel bar.