A Combined method of AC Impedance Measurement and BE Inverse Analysis for Detecting Corroded Rebar in Concrete Structure

交流阻抗测量与BE反演相结合的混凝土结构中钢筋锈蚀检测方法

基本信息

批准号：
10450045
负责人：
AOKI Shigeru
金额：
$ 7.1万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

An effective boundary element inverse analysis method was developed to detect the corrosion location and corrosion rate of rebars in a concrete structure. This method consists of two steps. The outlines of these steps are shown below.The first step is the effective non-destractive detection of corrosion locations by combining potential measurement and boundary element inverse analysis. The boundary element inverse analysis method for this step was developed based on the boundary element direct corrosion analysis method, which had been developed before. In this inverse method, the corroded part in the rebar net was approximated as a circle, i.e., the part of the rebars in the circle is taken to be corroded. The radius r and the coordinates (x, y) are taken as design variables, and the difference between the measured and calculated values of potential is taken as the cost function robe minimized. The polarization characteristics of the corroded and non-corroded parts are assumed to be gi … More ven. The minimization is performed through use of the Simplex method. The usefulness of the method was demonstrated by solving an example problem.The second step is the identification of the corrosion rate of the corroded part which was detected in the first step. The identification of the corrosion rate is performed by improving the AC impedance method. A boundary element inverse analysis was utilized to improve the AC impedance method. At first, it was verified experimentally that the potential in the concrete domain is described with the Laplace's equation. The potential at any point in the concrete domain can be calculated by solving the Laplace's equation with the boundary element method.Then, an inverse problem was formulated in which the location and the complex impedance (corrosion rate can be obtained from the complex impedance) of corroded part on the surface of a rebar are estimated from a small number of potential data measured on the surface of a concrete structure. The cost function to be minimized in the inverse problem is a function of difference between the measured and calculated values of potential. The validity and efficiency of the proposed method were demonstrated with an example in which a prismatic concrete block specimen with an embedded piece of rebar was used. Less

开发了一种有效的边界元反分析方法来检测混凝土结构中钢筋的腐蚀位置和腐蚀速率。该方法由两个步骤组成。第一步是有效的无损检测。本步骤的边界元反演方法是在之前开发的边界元直接腐蚀分析方法的基础上发展起来的。钢筋网近似视为一个圆，即圆内钢筋的部分被腐蚀，半径r和坐标（x，y）作为设计变量，电位的测量值和计算值之差。被视为腐蚀和未腐蚀部件的极化特性最小化。该最小化是通过使用单纯形方法来实现的。第二步是对第一步检测到的腐蚀部分的腐蚀速率进行识别，通过改进交流阻抗法来进行腐蚀速率的识别。首先通过实验验证了混凝土域内的电势可以用拉普拉斯方程描述，用边界元法求解拉普拉斯方程即可计算出混凝土域内任意点的电势。然后，一个提出了逆问题，其中根据在混凝土结构表面上测量的少量电位数据来估计钢筋表面上腐蚀部分的位置和复阻抗（可以从复阻抗获得腐蚀率）。反演问题中要最小化的成本函数是势能测量值和计算值之间差异的函数。通过一个带有嵌入件的棱柱形混凝土块样本的例子证明了该方法的有效性和效率。钢筋数量为较少使用。