Collapse mechanisms of power towers under wind loading

Abstract

In this paper, nonlinear static pushover analyses were carried out to assess the capacity and collapse mechanism of two existing transmission towers under wind loading. Different load distribution patterns were adopted from the application of the codified design wind load of the following countries: Mexico, United States, India, Japan and the New Zealand – Australian Code. Three-dimensional inelastic response analyses were performed using open access software. Analyses were employed to define the capacity curves, stress-strain curves for structural elements, the yielding mapping sequences and the collapse mechanisms, and to evaluate the influence of the tower body deformation and to assess the theoretical overstrength and ductility capacities. Results show a damage concentration, which leads to a fragile collapse mechanism with important strength reserves and a non-uniform distribution of yielding within the tower height. Since the collapse mechanism is not compatible with the desired performance inherent to the design philosophy, recommendations for the design stage are proposed, which pretend to ensure that the inelastic behaviour be consistent with the goals implicit in a code-based design to prevent tower collapses.