Assessment of the Structural Response of Transmission Lines Steel Towers when Subjected to Nondeterministic Wind Loadings

Resumo

The lattice steel towers have been widely used as supports for power transmission lines. In the current project practise, the structures dynamic behaviour usually is not considered. However, the main loading to consider in structural analysis of these steel towers is produced by wind loadings. Considering that many accidents associated to this kind of structural system occur even for wind velocities below that specified in project, its possible that most of these accidents have been produced by dynamic actions. This way, this investigation proposes an analysis methodology that can accurately simulate the coupled behaviour between the transmission line cables and the towers, when subjected to wind nondeterministic loadings, having in mind the assessment of the displacements and forces maximum values that occur in the steel towers. In this work, the investigated transmission line system, including the steel towers, conductors and shield wire types, presents two spans of 450 m associated to a main suspension tower in the centre with total height of 32.86 and other two towers at the ends. The conclusions of this research work pointed ou to relevant quantitative differences associated to the structural response, when was calculated based on a static linear analysis and compared to the results determined based on a geometric nonlinear and nondeterministic dynamic analysis.