Experimental study on the aerodynamic forces and wind-induced vibrations of stay cables with helical fillets

The rain-wind-induced vibration (RWIV) of stay cables has become a concern in bridge engineering over the past decades. Attaching helical fillets on the surface of stay cables is often used to suppress RWIV. In the critical Reynolds number range, stay cables also experience large amplitude vibration without rainfall, which is known as dry galloping. To investigate the optimal helical fillet parameters that can suppress RWIV and dry galloping, a series of wind tunnel tests were carried out. The results showed that a helical fillet can weaken the Reynolds number effect of the cable in the critical region, and the maximum CL and the decline value of CD are decreased. This effect gradually decreases with the decrease of helical fillet pitch, resulting in the decrease of the maximum CL in the critical region and the increase of CD in the supercritical region. The helical fillet has a good suppression effect on the dry galloping equilibrium position, and the suppression effect of the helical fillet on the dry galloping amplitude depends on the helical fillet parameters. A proper helical fillet setting can effectively suppress both RWIV and dry galloping. Compared with the helical fillet diameter, the suppression effect is more effective when changing its pitch. Finally, the drag coefficients in various Reynolds number regions are summarized to provide a reference for engineering design.