Application Of Modal-based Damage-detection Method To Locate And Evaluate Damage In Timber Beams

Abstract

This paper employs modal-based damage detection algorithms to identify location of defects commonly found in timber and to estimate their severities. In this study, the authors propose modifications to an existing damage detection algorithm for locating and evaluating damage by comparing the modal strain energy before and after damage using the first two flexural modes of vibration. Experimental verification was performed on pin-pin supported timber beams by employing the algorithms with extracted modal parameters using Experimental Modal Analysis (EMA). Single and multiple damage simulating pocket(s) of rot with various severities were inflicted by removing section(s) on timber beam specimens. The proposed damage indicator computed from the first two flexural modes was capable of detecting all damage locations. It was also able to estimate, with reasonable accuracy, the severity of damage in term of loss in sectional moment of inertia. The modified damage index method is in general reliable in detecting location as well as estimating the severity of simulated defects in timber beams.