Dynamic Wind Analyses of Transmission Line Structures

Transmission line (TL) structures are generally designed with a simplified static-equivalent approach described in the industry documents (IEC 60826, CENELEC, ASCE 74). These static equivalent methods are based on extensive in-situ testing and have been shown to be appropriate for typical TL structures. However, wind loading is a dynamic loading, and for certain cases it is difficult to capture dynamic response of the structure by a static equivalent method. As well, static equivalent method has limitations and the industry documents do not give any directions to design structures out of their scope. In this article, a set of numerical tools were used in order to assess wind-structure interaction for TL structures. At the present, the dynamic/turbulent wind loading data were numerically generated. The TL structures were modelled using finite element (FE) method that takes into account the inherent nonlinearities. Two wind loading studies are presented here: (i) a guyed tower; and (ii) a river crossing. The guyed tower was studied to show that its dynamic behaviour can have significant impact on wind effect on the structure which cannot be captured by static equivalent method provided in the industry documents. The river crossing was studied to understand better the implications of applying wind loads extrapolated from the ones used for normal TL structures, as compared to dynamic wind loading. For each case, comparisons with results obtained with static equivalent method are presented and discussed.