Three-Dimensional Flow Characterizations for Yawed and Inclined Circular Cylinders for Bridge Cable Stays

The vibrations induced by the wind on inclined cables of cable stayed bridges has been well established with both experimental and numerical investigations following observations made in the field of under construction and in-service long span structures. The characteristics and the patterns of the axial flow formed on the leeward surface of stay cables inclined and yawed to the direction of main wind flow is investigated in this study. To supplement the experimental and numerical work in this area, CFD simulations were performed on various cylinder models with cable inclination angles of 0°–60°, and yaw angles of 0°–40°. To determine the effect of the axial flow on the leeward side of the circular cylinder and the pressure induced on the cylinder the pressure coefficients distributions along the downstream surface of the circular cylinder model were investigated. From these it was noted that the change in the orientation of the cylinder, with both inclination and yaw as described above, changes the pressure distribution along with the development of rotational variations (appearance of rotating flow) of the flow along the leeward side of the circular cylinder. A frequency domain analysis was performed for characterizing the flow along the leeward side of the cylinder providing additional information compared to the time domain analysis. The coherence between the frequency components of the lift coefficient, the pressure coefficient along the leeward side of the cylinder, and the velocity near the leeward side of the cylinder was calculated, to determine the level of interaction between these parameters.