Aerodynamic interference between stay cables and suspenders of a long-span hybrid cable-stayed suspension bridge

Salient aerodynamic interference commonly exists between stay cables and suspenders in newly adopted hybrid cable-stayed suspension bridges and contributes to the wind-induced vibrations of the cable–suspender system. To better understand this aerodynamic interference effect, this study presents an investigation based on wind tunnel tests, employing a specifically designed cable–suspender system comprising a long stay cable and a set of tandem suspenders. The dynamic properties of the stay cable and suspenders are first analyzed, followed by separate examinations of their wind-induced vibrations. Then, the aerodynamic interference between the stay cable and suspenders is systematically investigated, considering key influencing factors, including wind velocity, wind direction, and the transverse distance between the stay cable and suspenders. Experimental results demonstrate that the vibrations of the stay cable increase with increasing wind velocity, which is generally consistent with the vibration behavior of a single stay cable without aerodynamic interference. However, the presence of the stay cable mitigates the wind-induced vibration response of the suspenders at a transverse distance of 7.74 times the stay cable's diameter. The vortex-induced vibration observed in the single stay cable at a reduced wind velocity Ur = 52 is attenuated when the suspenders are located downstream. When the wind direction α > 180°, upstream suspenders can suppress out-of-plane vibrations of the stay cable but amplify in-plane vibrations by 45% and 73% at α = 255° and 285°, respectively. Reducing the transverse distance between the stay cable and suspenders can generally enhance the out-of-plane vibrations of the stay cable as well as both the out-of-plane and in-plane vibrations of the suspenders. Additionally, the in-plane vibration of the stay cable increases significantly with increasing transverse distance at Ur = 250. These findings are anticipated to provide a useful reference for the wind-resistant design of long-span hybrid cable-stayed suspension bridges.