Experimental Study On Control Measures For Vortex-induced Vibration In Steel Box Girder Of Cable-stayed Bridge

With the application of new materials as well as development of design and construction technique,modern bridges are becoming longer and longer.Bridge tends to be long span,slender girder,light,flexible and small damping.Bridges are sensitive to the action of wind. Flutter,galloping,Vortex-induced vibration(VIV) ,Buffeting and wind rain induced vibration exist in steel box girder of cable-stayed bridges.But VIV is easy to excited in steel box girder of cable-stayed bridges under low speed wind. Although VIV is a kind of limited amplitude response,it occurs at low wind speed with relative large amplitude,which will affect the strength and fatigue of the structure and comfort of users.Therefore,it is significant to study the VIV of steel box girder of cable-stayed bridge, this thesis has a discussion on control measures for VIV of steel box girder of cable-stayed bridge.After the current theories and models of VIV are reviewed,the characteristics and the influence factors of VIV are analyzed and concluded.,aerodynamic means for VIV of bridge at home and abroad are introduced.Based on the North Bridge of Xiazhang Cross-sea Bridge.Designing and make section model of bridge following the theories of section model wind tunnel test,the wind tunnel test was carried out in the uniform wind field,and response of the bridge for wind action was measured.To research the influence of different aerodynamic means deeply on VIV,different aerodynamic means from different railing types,postion of repair-vehicle track to adding splitter plates,different flow deflectors of repair-vehicle track are designed in this thesis,measureing Vortex-induced response of different aerodynamic means varing with wind speed,attack angles are obtained. Comparing with the results of different aerodynamic means, splitter plate is more available than other aerodynamic means in controlling VIV of steel box girder of cable-stayed bridge.Comparing and analyzing the date of the test results,the influence law of Vortex-induced response of different aerodynamic means varing with wind speed,attack angles are obtained,trying to interpret different action effects on bridge VIV by different aerodynamic means from aerodynamic principle. At last, the results of this thesis can be reference of wind design for the same kind of bridges.