In the Thesis, using the experiment and computer modelling, the degradation of built-in piezoelectric transducers (PZT) in SHM and their impact on the performance of the structural monitoring system was studied. Comparison of the characteristics of the PZT in two functionally different states of the monitored object is used as a general basic principle for detecting design defects, which makes it possible to reduce the impact of degradation on the accuracy of the assessment of the state of the structure.