Impacts of cracks in concrete on characteristic parameters of electromagnetic wave transmission
DING Xiao1(), MO Si-Te1, LI Bi-Xiong2, HUANG Hua1
1. College of Electrical Engineering, Sichuan University, Chengdu 610065, China 2. College of Architecture and Environment, Sichuan University, Chengdu 610065, China
混凝土的使用越来越广泛,其健康状况越来越被重视。混凝土裂缝的发生发展特征是混凝土健康状况的重要表征参数。钢筋是混凝土固有结构,针对混凝土内部的裂缝,提出一种应用钢筋天线的裂缝监测方法,设置内嵌于混凝土中的发射、接收钢筋天线对,通过天线对S21参数的幅值来检测混凝土内裂缝。构建CST Studio Suite软件仿真模型,利用CST Studio Suite软件计算钢筋天线对S21参数幅值,分析S21参数幅值与裂缝状态的关系,结果表明混凝土内部的裂缝状态会对S21参数幅值产生明显的影响,根据S21参数幅值的特征可以实现裂缝检测。对无裂缝模型和有裂缝模型的S21参数幅值进行求比值处理,其比值超过某个阈值即认为能辨识裂缝,并将该段能辨识裂缝的频带定义为特征频带。仿真结果发现,不同裂缝厚度、不同裂缝角度、不同裂缝位置时的S21参数幅值均有显著变化,证明了在混凝土内设置钢筋发射、接收天线对,测量电磁波传播的S21参数,通过S21参数幅值可以判断混凝土裂缝及裂缝特征。
The occurrence and development characteristics of concrete cracks are important characterization parameters of concrete health. Given that steel reinforcement is the inherent structure of concrete, this paper proposes a method for monitoring cracks in concrete using steel reinforcement antennae. In this method, a steel reinforcement transmitting and receiving antenna pair embedded in concrete is set, and the cracks in concrete are detected according to the amplitude of the antenna pair' parameter S21 that can reflect electromagnetic wave propagation. To this end, a simulation model based on the CST Studio Suite software was constructed to calculate the amplitude of S21 using the software. The relationship between the amplitude of S21 and the crack state was analyzed. The results show that the state of cracks in concrete has a significant impact on the amplitude of S21, and thus the cracks can be detected according to the characteristics of the amplitude of S21. The cracks can be identified if the ratio between the amplitude of S21 obtained using the models with and without cracks exceeds a certain threshold. Meanwhile, the corresponding frequency band that can identify the cracks is defined as the characteristic frequency band of cracks. The simulation results show that the amplitude of S21 significantly changes with different crack thickness, crack angles, and crack positions. Therefore, the concrete cracks and their characteristics can be judged from the amplitude of S21 by setting up a steel reinforcement transmitting and receiving antenna pair in concrete.
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