Conductor forces on end transmission towers subjected to downbursts

Most weather-related transmission line failures are caused by High Intensity Wind (HIW) events such as downbursts. A crucial element of transmission lines’ structural integrity is the end towers, which should contain the incidents of cascading failure. The most challenging part in modelling and designing transmission lines is the conductors’ reactions since the conductors possess highly nonlinear structural behaviour. The aim of the current study is to provide simplified practical methods to estimate both the longitudinal and transverse reactions of the conductors on an end tower. Firstly, the critical downburst configurations that cause maximum longitudinal and transverse reactions on an end tower are determined through a parametric study of different downburst configurations. Then, the effects of different conductors’ parameters on their longitudinal reactions are studied. As a result, two methods are developed taking into account practical ranges of different parameters governing the conductors’ behaviour. The first method features the use of three-dimensional linear interpolation through a set of eight charts. The second method utilizes multiple regression analysis to develop a simple and accurate equation. Finally, equivalent uniform velocity factors are presented in order to calculate the transverse reaction acting on the end tower.