A revised Scruton number on rain-wind-induced vibration of stay cables

Abstract

Rain-wind-induced vibration (RWIV) is a typical large-amplitude vibration for stay cables. Due to the complex influencing factors and unclear mechanism, a Scruton number criterion Sc is usually adopted for RWIV-resistant design. However, this criterion has proved to be too conservative. The original Sc number characterized independently by mass and damping can not accurately reflect RWIVs' characteristics, and it is still difficult to compare test results with field measurement using the traditional Sc number. In this work, cable vibrations were studied through wind tunnel experiments and field measurements, and it is concluded that aerodynamic damping varies with mass also influences cables’ responses. The variation law of aerodynamic damping is analyzed by wind tunnel experiments, while the total damping of an actual cable of the Jintang Bridge has been identified by an empirical mode decomposition (EMD) method and the random decrement technique (RDT). A revised Sc* number with clear physical meaning considering aerodynamic damping is proposed. The aerodynamic damping for lighter models can be up 10 times that of prototypes, which makes the Sc* numbers the same order of magnitude. The results of different wind tunnel experiments and field measurements show that most large-amplitude vibrations occur at Sc* = 1–2.5. And, it is necessary to consider aerodynamic damping for more comparable work and more accurate prediction.