Abstract Summary
Overhead electrical transmission line conductors are prone to aeolian vibrations, resulting from the alternate shedding of vortices in the wake of the cable. Aeolian vibrations are characterized by small-amplitude high-frequency flexural oscillations and, whenever not properly controlled, can induce wear damage and fatigue failures of the conductor. The standard technical approach to the assessment of aeolian vibrations and residual life of overhead conductors is based on the Energy Balance Method (EBM) and the Poffenberger-Swart formula for bending stresses [1]. This approach relies on the main simplifying assumption of mono-modal oscillations, introduced by the EBM. Typical aeolian vibration records, however, clearly show that several modes can be simultaneously excited due to wind variations in time and along the span [2]. Aiming at overcoming the mono-modal vibration assumption of the EBM, a stochastic model was recently proposed by the authors. Wind forces are modeled as a narrow band stochastic process, centered around the Strouhal frequency of the conductor and with arbitrary cross-correlation in space. The model can also account for the presence of additional dissipation devices attached to the conductors [3]. The model is herein applied to achieve a full probabilistic description of the Poffenberger-Swart bending stresses, making a further step towards a more refined definition of the expected life of overhead conductors. References [1] EPRI - Electric Research Power Institute, 2006. Transmission Line Reference Book: Wind- induced Conductor Motion. U.S., Palo Alto. [2] Denoël V., Andrianne T., Real-scale observations of vortex induced vibrations of stay-cables in the boundary layer, Procedia Engineering (2017) 199: 3109-3114. [3] F. Foti, V. Denoël, L. Martinelli, F. Perotti, 2020. A stochastic and continuous model of aeolian vibrations of conductors equipped with Stockbridge dampers. Proc. of the XI International Conference on Structural Dynamic, (Eds.) M. Papadrakakis, M. Fragiadakis, C. Papadimitriou, Vol. 1, pp. 2088-2102.
