Estimation of parameters for distribution of timber pole failures due to inground decay

Abstract: Timber components are very popular due to its flexibility in use and therefore, widely used in bridges and building constructions, rail tracks and supply electricity throughout the world and in Australia. The main reason of this choice is for their high strength per unit weight, low cost and excellent durability. Reliability of these components is extremely important because a failure of these components may cause loss of money, loss of properties, injuries or even loss of lives. Reliability depends on various factors such as species of the timber, structural dimensions in design, environmental condition, human factors in installation, operations and maintenance. In general, the timber structure failures are due to the loss of load bearing capacity from the decrease in peripheral dimensions at or below ground level and loss of strength of timber fibre affecting bending resistance. Soil factors and related decays reduce the diameter and the strength of timber component affecting the safety in operation and service. Rotting of fibre can be from centre to outward or outward to centre by accelerating fungal and insect (termite) attack affecting reliability, availability, maintainability and safety of infrastructure assets. This paper is on investigating soil factors for modelling in ground decay and estimating parameters for failure distribution of timber poles. Real life data from electricity supply company in Australia have been used for modelling and validation. Results from this investigation can be used in optimal decision in maintenance and replacements for reducing the life cycle costs and risks of in-service failure of timber poles and infrastructure assets in similar environment