Dynamic response due to cable rupture in a transmission lines guyed towers

Abstract

The design of guyed lattice steel structures used in transmission lines (TL) is generally accomplished by static analysis, in order to simplify the dynamic actions, which are represented by "equivalent static loads". However, the static response to this type of structure is not always sufficient for design purposes, since such structures are lightweight, slender and that are always subject to dynamic nature action, except the own weight. Therefore, a dynamic analysis is critical to get a more precise result in terms of stresses on the bars and nodal displacements. In this context, this paper deals with the static and dynamic response evaluation of guyed lattice steel towers of TLs submitted to dynamic action of rupture cable. For this purpose, numerical models of isolated tower and completed stretch of TL were developed, including all components. The models are subjected to static analysis through "equivalent static loads" application coming from the rupture cable and dynamic analysis, in the time domain, using the Direct Integration Method (DIM) of equations of motion explicitly, with central finite differences for the problem solution. Finally, the results of static and dynamic analysis are compared, specifically the peak and final values (after the structure stops vibrating) with the static response values, in order to verify the dynamic amplification generated in the most realistic model against the results obtained from the model used in the usual design practice.