Galloping vibrations of overhead electrical conductors equipped with bretelle dampers

Bretelle dampers are short and slack metallic cables bridging two adjacent spans of an overhead electrical line. Whenever the damper is set in motion by the vibration of the line, it undergoes flexural vibrations characterized by a markedly hysteretic behavior. Since a long time, empirical observations have recognized the effectiveness of these devices to mitigate Vortex-Induced-Vibrations, while no experimental or theoretical study attempted to assess their performance in the mitigation of galloping vibrations. This paper presents a numerical investigation on galloping vibrations of multi-span conductors equipped with Bretelle dampers. A comprehensive finite element approach, previously developed within the research group to model galloping of single-span conductors, is adopted as a starting point and suitably modified to account for the presence of Bretelle dampers. The latter are modeled as geometrically non-linear beam elements characterized by a hysteretic bending moment-curvature relation. The procedure is applied to investigate a prototype two-span line section.