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.
