Large wind induced vibrations on conductor bundles: laboratory scale measurements to reproduce the dynamic behaviour of the spans and the suspension sets

Quadruple bundle large wind-induced oscillations leading to failures of I-type suspension sets are analyzed. Studies and analyzes performed on this problem with the aim of understanding the nature of the observed oscillations, the mechanism through which they are excited and the magnitude of the bending strains induced on the insulator strings are presented. Both computations and tests on an experimental span have been carried out to fully clarify the problem and submit an operative solution. Numerical modeling of the system behavior is presented together with the tests performed on the experimental span, in order to validate the proposed excitation and failure mechanism. The test setup design, performed by a mixed numerical-experimental procedure, is also described in detail. Finally, the solution adopted to limit the bundle oscillations within safe values is presented and discussed.