Abstract
The aggregate segregation detection in concrete core of concrete-filled steel tube (CFST) is a challenging task. In this study, numerical investigation on the detectability of concrete aggregate segregation in circular CFSTs using stress wave measurement with piezoelectric lead zirconate titanate (PZT) patches is performed. Multi-scale models of circular CFSTs composed of randomly distributed aggregates without and with aggregate segregation, mortar and interfacial transition zone (ITZ) are established with random aggregates method (RAM). By considering the piezoelectric effect of PZT patches, the coupling effects between the surface-mounted PZT actuator and steel tube as well as that between the embedded PZT sensor and mesoscale concrete core, multiscale and multi-physical-field coupling simulation on the stress wave propagation in the cross section of circular CFSTs with and without aggregate segregation is carried out. A sweep frequency voltage signal is adopted as input for PZT actuator and the effect of aggregate segregation on the embedded PZT sensor measurement is investigated. Numerical results indicate that the embedded PZT sensor response is affected by the aggregates segregation in concrete core. An evaluation index based on wavelet packet analysis on the output voltage response is defined, and its sensitivity to concrete aggregate segregation is analyzed. This study demonstrates the feasibility of stress wave measurement based aggregate segregation detection approach in concrete core of CFSTs with PZT sensors.
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