Predicting Dynamic Response of Structural Cables and Power Transmission Lines in Hurricanes and Other Windstorms

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Cables are often used in groups/bundles in a variety of engineering applications such as in suspension bridges, suspended roofs, guyed lattice towers, and power transmission. These cables are prone to large-amplitude vibrations in wind alone and in wind combined with precipitation (rain or ice). The vibrations can lead to fatigue damage and in some cases catastrophic failure of cables posing a threat to safety. Past investigations involving individual cables with smooth surface have resulted in an improved understanding of vortex-induced and rain-wind-induced vibration phenomena. However, there is a need for a credible wind load model that can be used to predict the dynamic response of bundled cables in turbulent and transient wind at moderate to high wind speeds. This research is to improve the resilience of cables used in cable-supported structures and power transmission lines to hazards of hurricanes and other windstorms. The study will facilitate development/evaluation of potential mitigation strategies leading to a reliable civil and power infrastructure. In this project, a synergistic computational and experimental approach will study galloping of bare-cable and cable covered with ice to address the technology gaps. The specific objectives are (a) to improve understanding of aeroelastic (motion-induced) behavior of a single and bundled cables used in cable-supported structures and high-voltage power transmission lines in moderate to high wind speeds, (b) to understand the effects of upstream turbulence, non-uniform flow, transient flow, and wake-induced flow on cable response, and (c) to develop a robust time-domain aeroelastic load formulation to predict cable vibration amplitude. The study involves high-fidelity computational fluid dynamics using large eddy simulation, and wind tunnel experiments using section models of single and multiple cylinders and aeroelastic models. The simulation and experiments will be for bare-cables and cables covered with ice in single and grouped configurations. Comparison of computational simulation and wind tunnel experiment results will provide credibility to both procedures. The primary product of this project will be a wind-load model for cables and a methodology that can be used as a tool in structural analysis to identify the vulnerability of cables in a structure or power line at a given wind site.