Rain-Wind Induced Vibrations in Stay Cables: a Parametric Study

A significant correlation was observed between the occurrence of stay-cable vibrations and the combined presence of wind and rain, as the latter led to the adoption of the term Rain-Wind Induced Vibrations. This phenomenon may generate oscillations over the stays, and then over the deck, with remarkable amplitude. The behaviour of a large number of stays was analysed, without external damping systems, different in length, slope, diameter, tension applied and inherent damping. These cables have been exposed to different environmental conditions represented by the rain and winds agents with different wind angles and speeds. The calibration of the used code has shown that a value of the inherent damping higher than the one actually evaluated should be used in order to obtain the vibration levels measured in reality. The analysis of the simulations showed that the number of stays that are affected by the vibrations is small if compared to the total number of tested configurations. This is due to the fact that in order to trigger the phenomenon a number of conditions concerning the geometrical configuration, the stress state of the element, and the environmental conditions to which the structure is exposed has to occur at the same time.