Research On The Crosswind Environment Of Vehicle Safety Around Bridge Towers

Cross-sea bridge is often in a very adverse wind environment, the deck design results in high wind speed and wind speed is larger than the ground environment. In addition, accessory structures amplify the wind speed. So the moving car is influenced by crosswinds. In such case, vehicles may rolls over and sideslip. In the sloping way, the wind against direction, vehicles may be lack of driving force or braking force, which would have a seriously affect on vehicle safety.In this thesis, Jiashao Bridge is regarded as the research background, which uses a single square tower structure and the wind generates separation through bridge tower, flow around in both sides accelerates violently, cars, which enters into the bridge tower from the normal wind velocity zone, will experience wind velocity enlarged area to leeward side of the bridge towers, then go through the other side of the enlarged area and then go out of bridge towers. Then the car goes out of bridge towers through the other side of the enlarged area. In this process, the change of wind speed is very violent, which has a great threat to traffic safety. In addition, as special structure of single tower, the wind flow from different directions have different effects on both sides of the lanes bridge towers, so with the change of wind declination and wind attack angle, its impact on wind environment cannot be ignored. This thesis carried out relevant research as the following aspects:1. According to the complex natural environment of the large-span bridges and analysis of the characteristics of long-span bridges wind speed distribution, simulation changes of wind speed in pylon area are imitated by numerical simulation (CFD). Based on the results, the researcher obtains three-dimensional view of tower zone beam segment flow distribution under different wind attack angle. Relatively, distribution law wind field is analyzed in tower region.2.1:20rigid model of large-scale with bridge tower as a center is carried on synchronization test in XNJD-3wind tunnel, which obtains a wind speed of the corresponding measuring point of deck. According to pre-established measures, it increased vibration grille and wind barrier on both sides of the bridge tower and contrasts deck wind field changes after additional measures, which can be an effective screening measures appropriately.3. Based on bridge tower three-dimensional numerical simulation calculations and impact of bridge tower to deck wind field distribution, and numerical simulation results are compared with experimental results. The results of wind tunnel experiments and the rationality of increased improvements are verified. The researcher also summarizes tower regional wind farms distribution law.4. The researcher summarizes this paper. We obtains some conclusions and proposes precautions and inadequacies. We finally points out problems to be solved during the future study.