Wavelet-Based Damage Detection of Multi-Degree-of-Freedom Structures

In this paper, a method is proposed to identify the occurrence and the location of damage from the responses of multi-degree-of-freedom (MDOF) structures based on the wavelet transform, which has the capacity to detect discontinuities and singularities. First, the propagation of singularities in responses is investigated qualitatively in order to explain how the structural responses are influenced by sudden changes of structural parameters (stiffness) resulting from damages. Next, in order to confirm the proposed method for complicated models, we evaluate the influence of sudden changes of structural parameters on responses quantitatively, and the relations between the wavelet transform and the damage location by the aid of the state space representation of the MDOF structures. Finally, laboratory-scale experiments are carried out to verify the performance and detectability of the proposed methods in a fourth story structural model installed by additional stiffness members.