Although the streamline box girder exhibits an excellent aerodynamic performance, they are often suffer severe Vortex-Induced Vibrations (VIVs) due to complicated separation and reattachment of air flows. It is necessary to apply control measures on the streamline box girder to suppress VIV. In this study, the VIV optimizations of a super wide streamline box girder were conducted via a series of section model wind tunnel tests. The effects of wind fairings, inspection vehicle rails, guide vanes, traffic barriers and handrails on the heaving VIV performance of the wide streamline box girder were analyzed. The test results show that the inspection vehicle rail and handrail are the main members to induce the heaving VIV of the box girder. A sharper wind fairing without changing the distance of railings is favorable to the heaving VIV performance. However, the countermeasures of changing the position of inspection vehicle rail and installing guide vanes under the girder have slight influences on reducing heaving VIV responses. Inspired by the spanwise sinusoidal perturbation method, the traffic barriers sealed with plates by regular intervals along the bridge deck can suppress the heaving VIV of the box girder successfully. The porosity of handrails has a significant effect on the heaving VIV. By using a sharp wind fairing and circular simplified handrails, the VIV performance of the wide streamline box girder was greatly improved. Their mitigation abilities were verified by a large-scale section model wind tunnel test.

In this study, the effects of wind barriers on the crosswind environment of vehicle safety on a long-span bridge with a streamlined bridge deck were investigated at different angles of attack (AOA). The profiles of the mean and the root mean square (RMS) of the wind pressure coefficients above different traffic lanes were obtained through synchronous pressure measurements. The mean pressure fields around the bridge decks were investigated by computational fluid dynamics (CFD) simulations. The crosswind environment of vehicle safety between the deck with railings and the deck with wind barriers was compared and analyzed in detail at different AOA. The results showed that the wind barriers produce a thicker separation shear layer above the bridge deck and result in a larger negative pressure region in comparison with the case with railings. This leads to a notable reduction in the mean wind pressure coefficients above the deck. The increase in the AOA enhances the above-mentioned reduction effect. It was also found that the wind barriers significantly increase the RMS of the wind pressure coefficients above the deck compared with the railings. The increase in the AOA inhibits this enhancement effect. The results of the equivalent mean pressure coefficients show that the wind barriers reduce the vehicle sideslipping risk more effectively than the vehicle overturning risk. It was also found that the effect of the wind barriers on the reduction of the overturning risk is more sensitive to the change in AOA than the effect on the reduction of the vehicle sideslipping risk.

Wind tunnel tests were performed on a 4:1 rectangular (REC) cylinder, a trapezoidal (TRA) girder, and a typical streamlined (STR) box girder to investigate the vortex-induced forces and their spanwise correlations. First, using the free vibration technique, the vortex-induced vibration responses and the Strouhal number were investigated at different Scruton numbers and attack angles. Then, the mean and standard deviations of the vortex-induced pressure coefficients of the three models were analyzed through simultaneous pressure measurements. The power spectral density and the spanwise correlation of vortex-induced pressures at some typical points were also studied. Finally, the spanwise correlations of vortex-induced forces acting on the three models in the cases of different vibration amplitudes and attack angles were investigated. The results show that the attack angle has a significant effect on the vortex-induced pressure distributions for the three types of girders. The second frequency components of the vortex-induced pressure occur near the trailing edge of the upper surface for the three types of sections. The correlation of vortex-induced force decreases with the increase in the oscillation amplitude for the REC model, but becomes larger for the TRA and STR models. With the increase in the attack angle, the spanwise correlations of vortex-induced forces on the three sections become weaker, especially for the REC model.

Study on the vortex-induced vibration (VIV) performance of structures under vibration states in turbulent flow fields is closer to the essence of bridge VIV in real service environments, which has been lacking in existing research. The key parameter used in the VIV performance evaluation, vortex-induced force (VIF) correlation, was focused on in this paper. A foundational streamlined box girder was selected, and free vibration sectional model tests were conducted in turbulent flow fields using synchronous pressure-vibration measurement. The results indicate that turbulence have an impact on the VIV performance of streamlined box girder. The presence of turbulence is likely to decrease the VIV amplitude, but sometimes it may also increase it. The phase difference between the leading and trailing edges of the structural upper surface is approximately 100°, and the vortices on the upper surface do not drift continuously. The streamwise correlation of VIFs decreases to varying degrees with the increase in turbulence intensity. The aerodynamic force spanwise correlation when the structure is stationary is significantly weaker than when it is in a vibrational state. When the structure experiences sustained VIV, the spanwise correlation of VIFs decreases with increasing turbulence intensity, increases with increasing amplitude, and decreases with increasing spanwise distance and tends to be constant at a certain distance. Finally, an extended model based on Ricciardelli's correlation function was proposed, which can better describe the VIF spanwise correlation of streamlined box girders under different amplitudes.