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Wind and Structures
  Volume 32, Number 4, April 2021 , pages 309-320
DOI: https://doi.org/10.12989/was.2021.32.4.309
 


A simplified vortex model for the mechanism of vortex-induced vibrations in a streamlined closed-box girder
Chuanxin Hu, Lin Zhao and Yaojun Ge

 
Abstract
    The vortex-drift pattern over a girder surface, actually demonstrating the complex fluid-structure interactions between the structure and surrounding flow, is strongly correlated with the VIVs but has still not been elucidated and may be useful for modeling VIVs. The complex fluid-structure interactions between the structure and surrounding flow are considerably simplified in constructing a vortex model to describe the vortex-drift pattern characterized by the ratio of the vortex-drift velocity to the oncoming flow velocity, considering the aerodynamic work. A spring-suspended sectional model (SSSM) is used to measure the pressure in wind tunnel tests, and the aerodynamic parameters for a typical streamlined closed-box girder are obtained from the spatial distribution of the phase lags between the distributed aerodynamic forces at each pressure point and the vortex-excited forces (VEFs). The results show that the ratio of the vortex-drift velocity to the oncoming flow velocity is inversely proportional to the vibration amplitude in the lock-in region and therefore attributed to the "lock-in" phenomena of the VIVs. Installing spoilers on handrails can destroy the regular vortex-drift pattern along the girder surface and thus suppress vertical VIVs.
 
Key Words
    streamlined closed-box girder; Vortex-Induced Vibrations (VIVs); simplified vortex model; vortex-drift pattern; time-frequency characteristics
 
Address
Chuanxin Hu:Department of Civil Engineering, Wuhan University of Science and Technology, Wuhan 430065, China

Lin Zhao:1)State Key Lab of Disaster Reduction in Civil Engineering, Tongji University, Shanghai 200092, China
2)Key Laboratory of Transport Industry of Wind Resistant Technology for Bridge Structures (Tongji University), Shanghai 200092, China

Yaojun Ge:1)State Key Lab of Disaster Reduction in Civil Engineering, Tongji University, Shanghai 200092, China
2)Key Laboratory of Transport Industry of Wind Resistant Technology for Bridge Structures (Tongji University), Shanghai 200092, China
 

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