Experimental study of cumulative damage detection in hysteretic structures using wavelet analysis of acceleration response

The authors have proposed the health monitoring system by using wavelet transform of response as a method evaluating the safety of structures quantitatively. This system can detect the abnormal signal that occurred in progress of the low cycle fatigue of structure under noisy condition. The wavelet transform provides the multi-resolution analysis and the frequency information locally in time in contrast to the conventional Fourier transform. In this study, the experiment using a simple structural model is carried out. Input motion is sinusoidal excitation. The discontinuity, which should be produced at the point changing from the elastic region to the plastic region in restoring force, is detected by wavelet analysis of acceleration response. Especially, the relationship of ductility factor and velocity at yield point, relationship of wavelet coefficient and velocity at yield point and so on are discussed.