Experimental Study on Vortex-Induced Vibration of Steel Tubes in Transmission Towers at Various Inflow Conditions

With the extensive construction of ultra-high voltage (UHV) transmission lines, the fatigue damage of steel tube members caused by vortex-induced vibration (VIV) in tubular towers has received growing attention. Although some progress has been made in the research of the VIV of steel tubes in uniform flow, there is still relatively scarce research on the VIV of steel tubes at various inflow conditions. In this paper, a series of wind tunnel tests are conducted to investigate the VIV of the steel tube subjected to uniform, turbulent, and oblique flows. Three turbulence intensities (I-u = 5.9%, 9.7%, and 12.6%), and four yaw angles (alpha = 10 degrees, 20 degrees, 30 degrees, and 40 degrees) are considered. The results show that the VIV response of the steel tube in the in-line (IL) direction is negligible compared to that in the cross-flow (CF) direction. The displacement amplitude gradually decreases as the turbulence intensity increases, accompanied by a more unstable response. For the inclined steel tube, the VIV maximum amplitude almost remains constant when alpha <= 20 degrees, while it sharply decreased in the case of alpha = 30 degrees and alpha = 40 degrees. Furthermore, it was found that the so-called independent principle is applicable for alpha <= 10 degrees.