Influence Of Bridge Tower And Wind Barrier On Both Wind Environment Over Bridge Deck And Trains Running Safety

The existence of bridge tower has complex effects on the distribution of wind field above bridge deck, resulting in an abrupt change of wind load that train suffers when it is passing through this area. Aiming to investigate the wind environment around bridge tower with the action of cross wind and skew wind, in this thesis, along span suspension bridge with steel box girder is studied, the influence of wind barrier installed nearby bridge tower is evaluated, and the running safety of train is analyzed by means of numerical method of coupling vibration of wind-vehicle-bridge system. The main research contents and conclusions are as follows:1) The computational fluid dynamics technology (CFD) was adopted to conduct a contrast analysis for the influence of bridge tower on the distribution of wind field above bridge deck by comparing the low of wind profiles at different locations cross-bridge and wind speed along bridge. Different forms of wind barrier were installed nearby bridge tower and the effect of wind weakening was discussed.2) Numerical simulation of coupling vibration of wind-vehicle-bridge system was implementing by the analysis software BANSYS under three cases:the distribution of wind field above bridge deck without the influence of bridge tower, with the influence of bridge tower, and with the influence of bridge tower and wind barrier. The lateral acceleration, vertical acceleration, derailment coefficient and wheel load reducing rate of a train under these three cases were discussed.Research on the wind environment around bridge tower shows that:wind speed above bridge deck around tower decreases with the action of cross wind, reduction efficiency of wind speed is weakening when the distance from bridge tower increases, resulting in an influence area about two times of tower width; The distribution of wind field above bridge deck changes little when the wind speed changes. Wind barrier can improve the wind environment in 5 meters above bridge deck effectively. The influence of wind barrier with different ventilation rate on wind profiles obeys the same rule. The wake effect of bridge tower under the action of skew wind is the same as the case under the action of cross wind, but the location of wake effect is different.Numerical simulation of coupling vibration of wind-vehicle-bridge system shows that: the value of lift coefficient of a train against the wind is quite small that the wake effect of bridge tower has little effect on vertical acceleration of train. Bridge tower and wind barrier mainly effect the lateral responses of vehicles running through a bridge, and have the same influence on lateral acceleration of a train. The wake effect of bridge tower on lateral acceleration,, derailment coefficient and wheel load reducing rate of a train is greater than that of wind barrier...