Durability analysis of a steel light pole subjected to wind excitations

Abstract

The durability of a square section steel light pole subject to severe wind induced oscillations is examined theoretically. Oscillations are due to a fluid-structure interaction phenomenon known as galloping. Theoretical pole response is determined and satisfactory agreement is found with observed pole behavior. Beam deflection theory enables the pole's displacement and loading to be determined from its oscillatory response and forms the link between the wind induced oscillations and a fatigue analysis. Pole oscillations result in fatigue cracks initiating from corners of a rectangular electrical access hole at the base of the pole. A combined finite element - fatigue analysis of the access hole provides life estimates for an assumed cyclic loading history. The link between wind induced oscillations and fatigue enables wind speeds causing the oscillations to be associated with a certain fatigue life, therefore a pole's susceptibility to fatigue cracks based upon its exposure to winds at different geographical locations are determined. Also studied are design improvements of the access hole that can extend the fatigue life.