Abstract Summary
As the strong wind effects, especially in mountain terrain and coastal regions, it may lead to road vehicle accidents while passing through long-span bridges. Many researchers have pointed this out and presented some related research work to analyze the coupled dynamic interactions of wind-vehicle-bridge system.This study mainly contributed to investigate the vehicle driving safety and physical comfort passing through a bridge tower region, considering strong cross wind environment variations in bridge tower regions.A long-span suspension bridge (Honghe Bridge) with a main span of 700 m was taken as research background.Honghe Bridge was located in southwest of China, a typical mountain canyon terrain with large undulations, and the terrain of the bridge site presented an “S” canyon cove landform.Considering the typical terrain impacts on the wind microclimate on the girder deck, the characteristics of the mean wind and turbulence wind at the mid-span and bridge tower regions were measured and analyzed.According to field measurement results, the typical wind curve model in tower regions along the bridge was proposed, as well as variation characteristics of strong turbulent and power spectral in bridge regions.Because strong shielding effects of the bridge tower on the incoming oblique wind flow, the wind speeds were drastically reduced while entering the tower region.However, the wind speed increased again after leaving the bridge tower regions which exhibited a significant acceleration effect on wind speed while leaving tower region.Compared to the standard wind curve model in tower regions suggested by Wind Load Specification, the measured results shown that the typical cross wind characteristics may impact vehicle dynamic responses in a large extent.A two-axle vehicle model was utilized to analyze coupled dynamic interaction between vehicle and bridge under such a typical time-varying cross-wind condition.The vertical, lateral, rolling, yawing, and pitching dynamic responses of a moving vehicle were discussed to gain a deeply comprehensive of system coupled dynamics.Influences of wind speed, turbulence intensities, vehicle speed, and dynamic bridge responses on a passing vehicle were also discussed.The road roughness in plane, driver reaction, and aerodynamic interference between the moving vehicle and bridge were included as well.The responses of vehicle passing by tower and main span were analyzed based on considerations of above factors.Driving safety and physical comfort analysis were also performed to revise the currently used limitation of driving speed on long-span bridge, and the definition of rolling and the side-slide accidents.Results shown that the lateral and rolling responses of vehicle model were greatly boosted by the cross-wind variations in tower regions along the bridge.The responses of vehicle model decreased sharply since the shielding effects of bridge tower on crosswind.However, the responses of vehicle model shown a significantly increasement while it gets out of bridge tower region, as a result of the acceleration effects of tower on cross-wind.The dynamic responses of vehicle model revealed that the vehicle driving safety influenced by wind microclimate, especially in bridge tower regions under influences of complex terrains.
