Experimental investigation of wind-induced vibration of multi-cross-section steel tube lightning rods in substation

Abstract

The multi-cross-section steel tube lightning rod (MSTLR) in the substation are susceptible to along-wind buffeting and vortex-induced vibration due to their inherent flexibility, low damping properties and multi-circular-section. This paper conducted a wind tunnel experiment on a 1:5 aeroelastic model of MSTLR under three wind fields with different turbulence intensity (uniform, 4.0%, and 7.0%). The amplitude, PSD, time-frequency curves, frequency components, and trajectory of wind-induced vibration are analyzed by measuring the acceleration responses at different heights and bottom reaction responses in the along-wind and cross-wind directions. A comparison was made between the relevant wind load parameters and those specified in the Eurocode. The results indicate that the distribution of the key participating modes exhibits different patterns with the variance of wind speed and turbulence intensity. Multi-order vibrations and structural coupling in orthogonal directions are observed with total response higher than the Eurocode. With the increase of turbulence intensity from 4.0% to 7.0%, the contribution of turbulence to along-wind acceleration response reaches saturation and has the opposite effects. When the speeds are 21.55 m/s and 27.33 m/s, respectively, the vortex-shedding frequencies of section 2 and section 3 coincide with the second-order natural frequency, and the vortex-induced resonance occurs. Those two vortex-induced resonances lead to a sudden increase in the standard deviation of the cross-wind response.