Age-Dependent Fragility Models of Utility Wood Poles in Power Distribution Networks Against Extreme Wind Hazards

Wood poles comprise a portion of the power utility´s aging infrastructure that make a significant impact on customer´s reliability. A large number may fail under the influence of severe wind storms and hurricanes, sometimes resulting in millions of dollars in replacement costs per year to the utilities. A holistic approach to risk assessment of wood poles in power distribution networks would therefore consider the simultaneous effects of decay and natural hazards on the failure probability of the poles. Toward this goal, this paper presents a framework for the development of age-dependent fragility curves of utility wood poles that relies on age-dependent probabilistic capacity models of wood poles and wind induced demand models. The framework considers uncertainties in the initial fiber strength of the wood poles, the age-dependent capacity loss model, the geometric features of wood poles of different classes, and the applied wind loads. The results of this study show that the decay process in wood poles may increase the fragility of the poles significantly as the age of the poles increase. The fragility curves provided in this research may constitute a major component of risk assessment approaches of power distribution networks against hurricanes and strong winds.