Seismic shear stress measurement using PZT based smart aggregate

A kind of smart aggregate for seismic shear stress monitoring in concrete structures is proposed. The SA uses d₁₅-mode PZT as the sensing element. A calibration test is designed in which cyclic shear stress with a dominant frequency of the earthquake response spectrum is applied on the two opposite sides of the proposed SA using a specially designed loading mold. The maximum applied stress is larger than the shear strength of ordinary concrete to allow for measurement during failure. The Finite Element (FE) model is established for researching the distribution of stress in the SA, and we calculate the sensitivity of the SA in theory. The calibrated sensitivity value and the calculated valve are approximately the same, indicating that the established FE model is reliable, the sensitivity of SA is also very stable in test result. In conclusion, the proposed SA can be used in monitoring the overall shear stress development process in concrete during a seismic event.