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 TLT's top horizontal along-wind displacements in the cross-line direction, nonlinear 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. (C) 2003 Elsevier Ltd. All rights reserved.