Experimental validation of a novel pseudo-modal approach for damage detection

Damage detection and localization in structural systems is experimentally studied. A novel pseudo-modal approach, recently proposed by some of the authors, is adopted. It is based on the comparison between free vibrations of the undamaged and damaged states, and aims to maximize the damage signature embedded in the data by exploiting the energy content of the vibration signals. Towards this goal, the latter signals are analyzed by means of the Orthogonal Empirical Mode Decomposition (OEMD) technique in order to derive a data-driven damage index, the so called Pseudo Modal Index (PMI). In this paper the results of an experimental campaign on a small-scale shear type steel frame structure are presented and discussed. The tested structure is modeled as a four degree-of-freedom dynamical system and the damage is represented by a localized stiffness reduction. A filtering technique applied to the Intrinsic Mode Functions is also proposed in order to tackle the presence of noise polluted data.