Experimental study on high-mode vortex-induced vibration of stay cable and its aerodynamic countermeasures

Abstract

In recent years, high-mode vortex-induced vibration (VIV) of stay cables has been observed in some cable-stayed bridges. It can cause undue stress and fatigue in the anchorages at the deck and/or pylons and in the cables themselves. In this study, experimental investigations were performed to characterise and control the high-mode VIV of stay cables by using horizontal- and inclined-rigid-stay-cable models. First, wind tunnel tests using the horizontal-rigid-dimpled-stay-cable model were performed to investigate the VIV characteristics of dimpled stay cables and effective VIV suppression measures. Wind tunnel tests were then conducted on an inclined rigid dimpled cylinder with and without helical fillets to investigate further the VIV characteristics of dimpled stay cables and effective suppression measures. Finally, stay-cable field measurements were made for comparison with the experimental results of the stay-cable model. The results show that stay-cable VIV can occur in cases of low damping, and the VIV of the stay cable can be effectively suppressed by increasing the damping ratio of the stay cable. Moreover, helical fillets with a diameter of d = 2.0 or 3.5 mm, which are usually used to control rain–wind induced vibration of stay cables in cable-stayed bridges, cannot effectively suppress the high-mode VIV responses of stay cables. The inclined-dimpled-stay-cable model with a damping ratio of 0.2 % at inclination angles of 25° and 40° exhibits significant VIV for the cases of wind yaw angles of 0°, 15°, -15°, and -30°. However, helical fillets with d = 10 mm (d = 0.07D, where D is the diameter of the stay cable) and pitch of 12D can effectively suppress the VIV responses of the stay cables.