Experimental Investigations of Material Properties of Timber Utility Poles Using Various Material Testing Approaches

Abstract

This paper presents an investigation of using different material testing approaches to determine material properties of timber utility poles from two hardwood tree species, i.e. Spotted Gum and Tallowwood. The material properties investigated are the Modulus of Electricity (MOE), the Modulus of Rupture (MOR) and the compression strength (CS) in longitudinal direction as well as radial and tangential directions of the cross section of the poles. These material properties are needed for the accurate modelling of timber poles using Finite Element Method (FEM) for the study of stress wave propagation and damage detection in timber utility poles. In open literatures, for most timber species such comprehensive material property data are scarce to find. Typically, material properties available are only in the longitudinal direction. Furthermore, most international standards cover only details on material testing in longitudinal direction and no coherent nor comprehensive guidelines are given for the testing of the full orthotropic material properties of timber. Hence, an extensive study is deemed necessary to investigate a suitable approach to determine full material properties of timber. Two hardwood timber species, namely Spotted Gum and Tallowwood are selected for this investigation. Beside full material properties, the investigation is extended to examine different material testing approaches (bending, compression and tension testing) for the determination of the same material properties. The presented material testing is conducted on numerous small clear specimens as well as on four full scale 5 m long timber pole specimens of the two mentioned hardwood tree species.