Characterization and Evaluation of Smart Concrete Modules Embedded with Piezoelectric Devices

The sensory behaviors of the concrete modules embedded with piezoelectric devices (PZT element) are characterized. Such PZT-embedded concrete modules demonstrate sensitivity to the load applied on the modules. In this case, the load produces stress in the concrete module, which is detected by measuring the equivalent circuit parameters (equivalent parameters for short) of the PZT element embedded in the module. In spite of stress, temperature also leads to the changes of the equivalent parameters of the PZT element, which makes it difficult to identify the effects of the stress and temperature on the PZT elements. However, it is also found that the characteristic frequencies are quite sensitive to temperature but have little dependence on stress. Such feature enables the characteristic frequencies to be used as reference parameters when the PZT elements are affected by both stress and temperature. In order to characterize the energy losses of the PZT element embedded in the concrete module, complex physical coefficients are introduced to the piezoelectric equivalent model, and a new method is proposed to calculate three dissipation factors which are used to represent the level of different energy losses respectively. In this method, the dissipation factors are looked as the function of the equivalent parameters of piezoelectric devices in specific mode, which simplified the computing of the dissipation factors.