A revised Scruton number on rain-wind-induced vibration of stay cables. Issue 230 (November 2022) - Chang, Ying
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 S c is usually adopted for RWIV-resistant design. However, this criterion has proved to be too conservative. The original S c 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 S c 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 S c * 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 S c * numbers the same order of magnitude. The results of different wind tunnel experiments and field measurements show that most large-amplitude vibrations occur at S c * = 1–2.5. And, it is necessary to consider aerodynamic damping for more comparable work and more accurate prediction. Highlights: The Scruton (Sc) number effects on the rain-wind-induced vibrations (RWIVs) were studied in wind tunnel experiments. Aerodynamic damping is approved to be an additional resistance during RWIV initial stage, which strongly dependents on vibration amplitude and mass. A revised Sc criterion considering aerodynamic damping is proposed for stayed cable wind resistance design .