Despite the evidence of energy transmission tower collapses due to tornadic events in the Brazilian territory, no national study treats the issue under strictly structural focus. In this context, as a starting point, mechanical global actions due to an approximate mathematical model of a F3 tornado, compatible with the Brazilian threat on two towers, one guyed and one self-supported tower, are evaluated; these tower models are largely used in the Paraná-Uruguai River Basins, critical on such occurrences. Comparisons with actions foreseen in design are performed in order to obtain the critical loading situations. Usage of tornadic response spectrum practices is proposed and particular aspects of tornadic loads on tower structures are analyzed.
tornado; transmission tower; wind
