Mechanism on the vortex resonance characteristics and countermeasures of the central-slotted box girders
YANG Ting,ZHOU Zhi-yong
State Key Laboratory for Disaster Reduction in Civil Engineering, Transport Industry Key Laboratory for wind ResistanceTechnique in Bridge Engineering, Tongji University, Shanghai 200092, China
To study the mechanism on the vortex resonance characteristics and countermeasures of the central- slotted box girders, the large-scale sectional model vibration measurement, pressure measurement as well as CFD are employed. This paper takes a long-span cable-stayed bridge over the Yangtze River as an example to conduct the wind tunnel tests of large-scale sectional model. The test results indicate that it is the inside maintenance rails located in the aerodynamic susceptible sites that cause the vortex-induced vibration of the bridge. CFD numerical simulation results show that the upwind flow passing through the curved soffit plate will be hindered by the inside maintenance rails, resulting in an increased width of dead water region forming in the wake of upwind box (and an enlarged drag coefficient), where a periodic and intense vortex shedding phenomenon occurs due to velocity gradient, giving rise to the VIV of bridge in the end. Accordingly, the inside maintenance rails are proposed to be moved towards the center line by a certain distance, which will not yet be an obstacle to the high-speed upwind flow. Thus the flow will separate in the location far away from knuckle line and diminish the size of dead water region forming in the upwind box wake as well as prevent the periodic vortex shedding. The static pressure test results show that when shifting the inside maintenance rails, the negative mean pressure at the soffit plate knuckle line will not change dramatically ,the fluctuating pressures on the upwind and downwind inclined panels can be reduced, and the fluctuating energy will be dispersed without a consistent predominant frequency. Wind tunnel test in case of modified section are conducted and the results show that the VIV of the bridge can be suppressed completely.
杨 婷,周志勇. 中央开槽箱梁涡激共振特性及抑振措施机理研究[J]. 振动与冲击, 2015, 34(10): 76-83.
YANG Ting,ZHOU Zhi-yong. Mechanism on the vortex resonance characteristics and countermeasures of the central-slotted box girders. JOURNAL OF VIBRATION AND SHOCK, 2015, 34(10): 76-83.
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