Active Interfacial Performance Monitoring for Concrete Filled Steel Tube with Embedded PZT Techniques Using Power Spectral Density Analysis

The debonding between the steel tube and the concrete core of Concrete-Filled Steel Tube (CFST) member can weaken the confinement effect of steel tube on core concrete and may lead to the decrease in load-carrying capacity and in ductility. In this paper, a kind of multi-functional smart aggregate (SA) which is based on piezoelectric Lead Zirconate Titanate (PZT) is employed to detect the predesigned interfacial debonding damage in a CFST column specimen. Three SAs are embedded into the concrete of the specimen as actuators and a number of PZT patches are bonded on designed locations of the outside surface of the steel tube as sensors. Laboratory tests are performed on the CFST column. The responses of all the employed PZT sensors are measured when one of the SAs is excited with sweep sinusoidal signals. Based on the analysis on the power spectral density (PSD) of the employed PZT sensor measurements, the artificially mimicked debonding areas are detected successfully.