纵向肋条对斜拉索气动力和涡激振动特性影响的试验研究

Experimental study on the influence of longitudinal ribs on the aerodynamicforce and vortex-induced vibration characteristics of stay cables

斜拉索的风雨振和涡激振动是广受关注的风致振动问题,为了抑制风雨振,在斜拉索表面设置纵向肋条,是常用的气动措施之一。纵向肋条的参数对涡激振动性能的影响,以及对斜拉索气动力的影响,是值得研究的问题。通过风洞试验,在斜拉索表面布置了宽度和高度均为5 mm的长方体肋条,研究了2根肋条在不同位置α下,斜拉索的气动力及涡激振动的变化规律。结果表明:对于气动力,当布置的肋条位置α≥25°时,雷诺数对斜拉索的风压分布基本没有影响;当布置的肋条夹角α≤30°时,有肋条斜拉索的平均阻力系数均小于无肋条斜拉索;当布置的肋条位置α≥35°时,斜拉索的平均阻力系数和平均升力系数不随雷诺数发生变化,而当肋条位置α=60°时,斜拉索的平均阻力系数达到最大值,约为1.7。对于涡激振动,在肋条位置α=55°的工况下,斜拉索的涡激振动被完全抑制,可以运用在实际工程以抑制斜拉索及相关细长柱体结构的涡激振动;但当位置为60°时,斜拉索的涡激振动振幅虽然比无肋条状态有所减小,但涡振的风速锁定区间会被放大,在实际工程中应充分考虑这一现象。

Rain-wind-induced and vortex-induced vibration of stay cables are widely concerned problems of wind-induced vibration.In order to suppress wind rain vibration,setting longitudinal ribs on the surface of stay cables is one of the commonly used aerodynamic measures.The influence of the parameters of the longitudinal ribs on the vortex induced vibration performance and the aerodynamic force of the stay cable is worth studying.Through a wind tunnel test,the aerodynamic force and vortex induced vibration of a stay cable under different included positionsαwere studied for the rectangular parallelepiped ribs with width and height of 5 mm arranged on the surface of the stay cable.Results show that for aerodynamic forces,Reynolds number has little effect on the wind pressure distribution of stay cables when the included position of ribs isα≥25°.When the included position of ribs isα≤30°,the average resistance coefficient of stay cables with ribs is smaller than that of cables without ribs.When the included position of the ribs isα≥35°,the average resistance coefficient and the average lift of the stay cable do not change with the Reynolds number,while when the included position of the ribs isα=60°,the average resistance coefficient of the stay cable reaches the maximum,which is about 1.7.For vortex induced vibration,under the condition of rib included positionα=55°,the vortex induced vibration of stay cables is completely suppressed,which can be applied to practical projects to suppress the vortex induced vibration of stay cables and related slender column structures.However,when the included position is 60°,although the vortex-induced vibration amplitude of the stay cable is smaller than that of the cable,the wind speed locking range of the vortex-induced vibration will be amplified,which should be fully considered in practical engineering.