DETECTION OF UTILITY POLE ROT DAMAGE BY MEASURING THE REFLECTION COEFFICIENT

This paper presents a novel nondestructive approach for determining th e presence of rot in wood telephone/utility poles carrying telephone a nd power lines. The method requires determination of the reflection co efficient of the buried end of the pole using physical point measureme nts such as position, acceleration, or strain. Wave propagation analys is is used to characterize the one-dimensional structural dynamics of the wood pole. This approach permits directional wave components which propagate up and down the pole to be extracted using a previously dev eloped wave filtering scheme.((1,2)) These sensed directional wave com ponents can then be used to compute the local reflection coefficient o f a structural discontinuity based on longitudinal, transverse, or tor sional excitation. The reflection coefficient yields information about the location and extent of pole rot in wood utility poles. Temporal d ata of incident and reflected wave components also permits a visual ch aracterization of the effect of pole rot on the structural response of the utility pole. Experimental results are obtained on two laboratory test specimen excited in the axial direction to confirm analytical pr edictions.