Dynamic behavior and stability of transmission line towers under wind forces

A new analytical-numerical modelling for the structural analysis of transmission line towers (TLT) under wind action is presented and proposed as a rational procedure for stability assessment in a design stage. The numerical results obtained from a 3D finite element model are discussed in relation to the dynamic behavior and the mechanism of collapse of a typical TLT. A simplified two degree-of-freedom analytical model is also presented and shown to be a useful tool for evaluating the system fundamental frequency in early design stages. In order to reduce the TLTʹs top horizontal along-wind displacements in the cross-line direction, non-linear pendulum-like dampers (NLPD) installed on the towers are envisaged and their efficiency is demonstrated with the aid of comparisons between numerical results obtained from the controlled and the uncontrolled systems.