EXPERIMENTAL STUDY ON SENSITIVITY OF EMBEDDED PZT IMPEDANCE TRANSDUCERS TO CRACK DAMAGE OF REINFORCED CONCRETE BEAM

摘要

Reinforced concrete(RC)structure is one of most familiar engineering structure styles in the civil engineering community,which often suffers crack damage during their service lives because of some factors such as overloading,excessive use,and bad environmental conditions.Thus health monitoring of RC structure is of special concern.Piezoelectric materials(such as PZT)have direct and converse piezoelectric effects and can serve as impedance transducers.A new health monitoring method based on electromechanical impedance(EMI)measurements is addressed in this paper,which use the electromechanical coupling property of embedded PZT transducers.The embedded PZT transducers are designed and made with naked PZT,waterproof and encapsulation materials in the study.An experiment study on health monitoring of a RC beam is also implemented to discuss the sensitivity of embedded PZT transducers to the crack damage.In this experiment,the electrical admittances of two kinds of embedded PZT transducers are measured when the RC beam is suffering from variable loads.From the obtained test signatures it is found that the presence of incipient crack damage of the RC beam can be captured by the uncovered PZT impedance transducers.The encapsulated PZT transducers by using cement,however,are relative insensitivity to the crack damage of RC beam.