Study On The Theoretical Models Of Rain-wind-induced Vibration Of Cable And Analysis On Vibration Characteristics

With the increasing of span of cable-stayed bridges, the length of stay cable isbecoming longer and longer, many kinds of wind-induced vibration of cables occurredeasily owing to the characteristics of small mass, large flexibility and low inherentdamping of cables. In these cables vibration forms, the large-amplitude rain-wind-induced vibration is harmful especially. Scholars of the world have done a great deal ofresearch on rain-wind-induced vibration of cable, but existing theoretical models havelots of imperfect places and can not reflect characteristics of this cable vibration formcomprehensively.Base on extensive reading of existing research literatures, the merits anddeficiencies of former theoretical models of rain-wind-induced vibration of cable arereviewed, and research contents of this paper are determined.According to the soakage theory, Prandtl boundary layer theory and static waterboundary layer theory, the interactive force between the cable surface and the rivulet isrestudied. The existence of the Coulomb damping force and the linear viscous dampingforce is demonstrated, and calculation formulas of these two damping forces arededuced.Using two freedoms theoretical model of rain-wind-induced vibration ofsegmental cable with moving rivulet, the influence of the surface material of cable onrain-wind-induced vibration and reasonable value of the linear viscous damping forcecoefficient are studied. Combining the theoretical model of rain-wind-inducedvibration of segmental cable with quasi-moving rivulet which established in this paper,the regularity of coupling vibration between cable and rivulet is analyzed, andoccurring conditions of rain-wind-induced vibration of cable are proposed. Using threefreedoms theoretical model of rain-wind-induced vibration of segmental cable withmoving rivulet, the regularity of in-plane/out-of-plane vibration of cable and the effectfactors of vibration trajectory dip angle of cable section are analyzed.By analyzing the phenomenon of rain-wind-induced vibration of cable anddifferent of influencing factors in detail, the theoretical models of rain-wind-inducedvibration of continuous elastic cable with moving rivulet which considered in-planevibration only and in-plane/out-of-plane simultaneously are established respectively.Using these two theoretical models, the vibration characteristics of cable, thedistribution regularity of rivulet along cable and its influence on cable vibration, the regularity of coupling vibration between cable and rivulet, the influencing regularity ofthe power exponent of wind speed profile on rain-wind-induced vibration, theregularity of in-plane/out-of-plane coupling vibration of cable, and the influencingregularity of the turbulence intensity of wind field on rain-wind-induced vibration arestudied systematically.Reasonable explanation for the above research content is given from physicssignificance and mechanical principle. The theoretical results are in good agreementwith those obtained in the test and measurement. The consistency shows that thetheoretical models which established in this paper can consider various kinds ofinfluence factors and more fully reflect the vibration characteristics of rain-wind-induced vibration of cable than existing ones. Using these models, researchers canfurther study the occurring condition and mechanism of this cable vibration form withmathematical and mechanical instruments and analyze quantitatively, which providesreference for design and cable vibration control.