Impedance-Based Health Monitoring of Civil Structural Components

This paper presents experimental evidence on the use of the impedance-based health-monitoring technique on components typical of civil structures. The basic principle behind this technique is to utilize high-frequency structural excitations (typically >30 kHz) through a surface-bonded piezoelectric sensor/actuator to detect changes in structural point impedance due to the presence of damage. Real-time damage detection on composite-reinforced concrete walls was investigated and the capability of this technique to detect imminent damage, well in advance of actual failure, was confirmed. Concepts that directly applied to this technique itself, such as effects of boundary condition changes and the effects of temperature changes, were also investigated. Experimental investigations were carried out on a 1/4-scale bridge element and a pipe joint commonly found in civil structures, to verify robustness of the technique to changes in environmental conditions. Data collected from the tests demonstrate the capability and the effectiveness of this technology to monitor the condition of various civil structures.