| Cable-stayed bridge is composed of the stay cable, the bridge tower and thegirder. Due to its excellent mechanical property, reasonable price and sophisticatedfacade, the cable-stayed bridge has become the most competitive one in thelong-span bridge. Cable is the main portion to bear the all weight, when the windblows from one side, there is periodic vortex-shedding in the zone of wake, whichwill induce the transverse and streamwise unsteady load, then cause the vibrationresponse. The long time vibration will incur the structural fatigue and make thepeople on the bridge feel uncomfortable, so it is important to study the characteristicof the votex-induced vibration of the stay cable.We choose a new-type wavy cylinder as the object of study, for its top andbottom spread by sinusoid along the span direction, it delays the separation of thefree shear layer, and it also restrains the Karman vortex street. When the bestcombination size happens, the reduction of the drag coefficient can be18%and thelift coefficient will be almost zero. Basing on the N-S equation and ALE dynamicmesh technique, we study the transverse and streamwise forced vibration of λ*=2and λ*=6wavy cylinder when Re=100. Finally, we get the variation of the dragcoefficient and lift coefficient with the changing of the vibration frequency, and wecan also get the lock-on intervals and2P,2S, P+S vortex shedding under thedifferent amplitudes.The result prove that: when the transverse forced vibration happens, for theλ*=2wavy cylinder, the reduction of the drag coefficient is not very obvious, it canonly work when it before the lock-on interval, but it can reduce the vibration tosome extent. For the λ*=6wavy cylinder, the biggest drag reduction can be25%and15%, and the lift reduction can be93%and78%corresponding to the amplituderatio is0.2and0.4, and we can get the2P and2S models in the wake; when thestreamwise forced vibration happens, the λ*=2wavy cylinder can reduce thevibration only when the amplitude ratio is0.1, but for the λ*=6wavy cylinder, it cannot only reduce the resistance but also the vibration very well when the amplituderatio is0.1and0.3, which exerts the advantage of aerodynamic performance. wecan get the different models in the wake flow, including the A-I model, A-III model and A-IV model, they can exchange to each other in some conditions and competewith each other.In this paper, we study the transverse and streamwise forced vibration of thewavy stay cable, which have lays the foundation of the further vibrationperformance study of wavy stay cable. |
