钢管混凝土结构受到荷载作用、服役环境和混凝土收缩等因素影响，容易出现钢-混凝土界面的脱粘和脱空等缺陷，开展钢-混凝土界面的缺陷检测对于保障结构安全具有重要意义。当前，针对钢-混凝土界面缺陷的无损检测方法中，机电阻抗法（EMI）利用压电陶瓷传感器（PZT）的阻抗信息检测结构缺陷，并以其经济、高效和精确度高等优点而受到广泛关注。但是传统的机电阻抗检测方法主要采取外部粘贴或内部埋置PZT传感器的检测技术，限制了PZT传感器的重复利用、检测速度和应用场景。为解决这一问题，本文基于理论推导、实验验证和数值模拟，提出了一种新型的压耦式机电阻抗检测技术，并基于此开发出一套适用于钢管混凝土结构的钢-混界面缺陷检测装置——环箍式检测装置。本文主要研究内容如下：

（1）建立压耦式机电阻抗技术的理论模型，推导理论公式。根据粘贴式双自由度耦合模型，提出压耦式多自由度耦合模型，提出合理假定并简化模型。根据压电方程和动力方程，推导出压耦式电导纳方程，并得出关键影响参数——界面耦合刚度k₄。同时，对各结构阻抗参数（质量m、刚度k、阻尼c）合理取值，研究k₄数值对电导曲线的影响，初步验证理论公式。

（2）压耦式机电阻抗技术的实验验证和数值模拟研究。设计并搭建小荷载压力试验装置，验证压耦式机电阻抗测量技术的稳定性和灵敏度。通过6组重复荷载加载实验，研究外加荷载对压耦式机电阻抗检测技术稳定性的影响。通过结构缺陷检测实验，研究外加荷载对压耦式机电阻抗缺陷检测技术灵敏度的影响。对比表面粘贴式，分析压耦式机电阻抗技术的缺陷检测性能，验证压耦式缺陷检测的可行性。建立压耦式数值模型，开展压耦式检测技术的关键参数分析，验证理论公式和实验结果。

（3）面向钢管混凝土结构的钢-混凝土界面缺陷，开发并验证环箍式检测装置。基于压耦式机电阻抗技术，开发环箍式检测装置，并将其应用到钢-混凝土界面缺陷检测。实验中分别对钢管混凝土结构的多处位置进行检测，对比分析钢-混凝土界面缺陷和界面完好的电导曲线特征，验证环箍式检测装置的可行性。利用数值模拟排除实验干扰因素，解释实验现象。

Concrete-filled steel tube (CFST) structures under service conditions are prone to steel-concrete interfacial damages, like debonding and voiding. Damage detection at the steel-concrete interface becomes crucial for ensuring their structural safety. In recent years, the electromechanical impedance (EMI) methods have been employed to detect structural damages with the help of piezoelectric ceramic sensors (PZTs) due to their advantages of economy, high efficiency, and high accuracy. However, the traditional PZT sensors were usually implemented into the structures by external adhesive bonding or internal embedding. These implementations limit the reusability of the sensors, resulting in the waste in cost and labor. In this study, we proposed a novel pressure-coupled damage detection technique, and verified this technique theoretically and experimentally. Furthermore, a novel hoop-type detection device was developed and validated experimentally on detecting steel-concrete interfacial defects. The main contents of this work include:

(1) The theoretical model for the pressure-coupled EMI technique has been developed, with the derived theoretical formula. A pressure-coupled multi-degree-of-freedom coupling model has been proposed based on the classic two-degree-of-freedom model. By solving the mech-electric equation of the dynamic model, we derived the pressure-coupled admittance formula and discovered the key parameter k₄ (the interfacial coupling stiffness). Furthermore, the influence of k₄ on the conductance signatures were investigated on the conductance signatures in models with reasonable parameters.

(2) We conducted experimental and numerical research on the pressure-coupled EMI technique. A tailored load pressure test device was designed and built to assess the stability and sensitivity of the measurement technique. In six sets of repeated load experiments, we examined external loads' influence on the stability of the pressure-coupled EMI technology. During structural defect detection experiments, we evaluated the impact of external loads on the technology's sensitivity to defect detection. Comparative analysis with surface bonding methods demonstrated the superior defect detection performance of the pressure-coupled EMI approach. Additionally, a pressure-coupled numerical model was constructed to analyze the influence of k₄.

(3) A novel hoop-type detection device, utilizing pressure-coupled EMI technique, has been developed and validated for detecting steel-concrete interfacial damages in CFST structures. By using the hoop-type devices, multiple interfacial damages in the CFST samples were tested and compared with intact samples. The results verified the feasibility of the hoop-type detection device. Additionally, numerical simulations were employed to minimize experimental interference factors and elucidate the observed phenomena, further validating the experimental findings.