Three‐Dimensional Model for Wood‐Pole‐Strength Predictions

Abstract

A three‐dimensional finite element model was developed to predict the strength and failure location of nine wood transmission poles made from three commonly used North American species. All poles were 1,524–1,829 cm (50–60 ft) long, and were tested to failure as cantilever beams. The analysis methodology involved considering several 45.7‐cm‐ (18‐in.‐) long segments, located along the pole length, that contained the most severe inherent characteristics. Each segment was analyzed recognizing actual material properties and appropriate boundary conditions. Important material properties for each segment were determined by measuring clear‐wood elastic and strength parameters in undamaged sections taken from tested poles. The flow‐grain model was used to describe the grain deviation around knots. For the nine poles studied, predicted and experimental strength values differed on average by 7%. The correct location was predicted in six of the nine poles studied. Where failure location was not predicted correctly, the failure was due to some pole characteristic not perceptible from a surface inspection.