Dynamic structural analysis of transmission lines steel towers subjected to nondeterministic wind loadings

Resumo

In the current design practise of steel latticed towers used to support electrical transmission lines, the structure’s dynamic behaviour is not considered. However, the main loading to be taken into account in the structural analysis of electrical transmission lines steel towers is produced by the wind loads, which acts dynamically over the structural system composed by towers and cables. In addition, it’s not uncommon for slender towers to present disadvantageous dynamic properties, making them vulnerable to the wind action. Considering that many accidents associated to this kind of structure occur even for wind velocities below that specified in project, it’s possible that most of these accidents have been produced by dynamic actions. This research work proposes an analysis methodology that can accurately simulate the coupled behaviour between the transmission line cables and the suspension structures, when subjected to wind nondeterministic actions, including in the dynamic analysis the effects of the geometric nonlinearity and the aerodynamic damping. The results obtained in this work indicated that the dynamic response can be relevant to the system structural behaviour, and in this scenario the use of a static analysis can lead to a non-trustable design of the towers.