Damage Detection for Beams subject to Moving Loads based on Wavelet Transforms

This paper provides an efficient method based on wavelet transforms in order to detect and localize damage on structures subjected to moving loads. Two different models based on the characteristics of the test-rig utilized in this study are developed. An analytical model consisting in a concentrated mass passing over an Euler-Bernoulli beam is created, where damage is modeled as a rotational spring. On the other hand, a finite element model is also developed, different types of damage on the bridge are simulated and transient analyses are performed by incorporating a load which moves constantly along the beam nodes. Continuous wavelet transform diagrams using the vibration responses show that damage can be identified and localized even with significant percentages of noise. Nevertheless, the method is improved by filtering the signals, removing the border effects, and calculating the total wavelet energy of the beam from the coefficients along the selected range of scales. Thus, the accumulation of wavelet energy could indicate the presence of damage. Finally, laboratory experiments are conducted to validate this work.