Experimental Study on the Influence of Twin-Box Girder Attachments on the Driving Wind Environment of a Long-Span Coastal Bridge under Crosswind

The influence of twin-box girder attachments on the driving wind environment of a long-span coastal bridge under crosswind was experimentally studied in a boundary layer wind tunnel. First, the particle image velocimetry (PIV) technique and anemometers were used to determine the optimal PIV window size. Then, the effects of attachments and vehicles on average wind speed, turbulent kinetic energy, Reynolds stress, and equivalent wind speed reduction coefficient on the driving wind environment were analyzed. Results indicate that bridge attachments alter both the magnitude and distribution of average wind speed on the windward side of the vehicle. Turbulent kinetic energy peaks were observed near the windward side of attachments, particularly in the wake region above the vehicle. Reynolds stress peaks were primarily located on the windward side of the attachments; increasing the height of the attachments expanded the peak area above the vehicle while reducing the wake region’s area. The coefficient of equivalent wind speed reduction provides a reasonable quantification of changes in the driving wind environment. However, the difference between conditions with and without the vehicle was significant, suggesting that practical wind barrier solutions should prioritize aerodynamic measurements of vehicles behind wind barriers.