Modelling of tornado and microburst-induced wind loading and failure of a lattice transmission tower

Many transmission line and tower failures worldwide are attributed to high intensity winds (HIW) associated with tornadoes and microbursts. This paper describes models fur the wind velocity time-histories of transient tornado and microburst events and the resulting loading on a lattice tower. A dyna mic structural analysis has been undertaken for two HIW events, predicting a tornado-induced shear failure, as observed in the field. However, the mic roburst does not produce failure, due to its lower intensity and longer dur ation. Indeed, such failures, if they occur in practice, are likely to be a ssociated with a more broad-fronted microburst loading in which conductor l oads contribute. (C) 2000 Elsevier Science Ltd. All rights reserved.