Detection and localisation of damage in bridge model by spatial wavelet based approach

摘要

The objective of current work is to show through modelling of a bridge with damage, the effectiveness of using wavelet transform by means of its capability to detect and localise damage. The spatial data required by the wavelet transform are derived from the mode shape data of the bridge model using (ANSYS 8.0) for undamaged and damaged cases. Damage is induced by reducing stiffness of only 4-6 elements. The wavelet coefficients are derived at various scale indices as to show the effect of local perturbations in coefficients due to difference in mode shapes of damaged and undamaged cases of first few modes to quantify the damage index and location. The Continuous Wavelet Transform (CWT) using complex Gaussian wavelet is used to get the coefficients. It is observed that by using wavelet transform on the modal data as input, damage can be quantified even at very small levels of damages and one can usefully exploit appropriate mode(s) showing larger sensitivity of detection.