基于压电阻抗的混凝土裂缝深度发展定量研究

混凝土结构是土木工程领域使用最广的结构形式,裂缝是其损伤的主要形式。该文基于压电阻抗(EMI)监测技术,对混凝土立方体标准试块裂缝深度的定量发展进行了监测。制作150mm×150mm×150mm标准试块,将压电片(PZT)粘贴于试块表面,用精密阻抗分析仪HP4294A提取压电片在混凝土试块健康状况和不同损伤工况下的电导纳信号,并分析二者的联系。实验结果表明,随着裂缝损伤的发展,压电片电导纳频谱发生了变化;压电片-粘结层-主体结构耦合系统的共振频率及电导信号峰值能表征混凝土裂缝深度的发展,但其存在稳定性缺陷;传统损伤指标中,绝对比例平均偏差(MAPD)和均方根偏差(RMSD)比相关系数(CCD)更适于监测混凝土裂缝的出现,而CCD则比MAPD和RMSD更适于定量分析裂缝的发展。此外,该文还得到了混凝土试块裂缝发展时损伤参数的具体数值,可供EMI健康监测实际应用时参考。

Quantitative Study on Crack Development in Concrete Based on EMI

Concrete structure is the most widely used structure form in civil engineering, and crack is its main damage form. Based on the electro mechanical impedance (EMI) monitoring technique, The experiment was carried out to monitor the crack quantitative development in concrete cubes.The concrete test cubes with size of 150 mm×150 mm×150 mm were prepared,and PZT piezoelectric patches were bonded on the surfaces.An impedance analyzer HP4294A was used to extract the admittance signals of concrete cubes corresponding to healthy condition and several damage conditions,and the relations between them was studied.The results showed that the admittance signals varied with the development of crack in concrete.The peaks of conductance signals and resonance peaks of the coupling system of piezoelectric patches cohesive course main structure could indicate the crack development in concrete cubes,but its stability was poor. Among the traditional damage index,the mean absolute percentage deviation(MAPD) and root mean square deviation(RMSD) were more suitable for monitoring the emerge of crack in concrete than the correlation coefficient deviation(CCD),while CCD was more suitable for the quantitative analysis of crack development than MAPD and RMSD. Besides, some specific values of damage index of crack development in concrete cubes were obtained, it was available for health monitoring application based on EMI.