Buffeting Response Of A Long-Span Cable-Stayed Bridge With Composite Beam Over Mountainous Terrain

Due to the limitation of complex terrain condition,most bridges in mountainous areas are high-pier and long-span bridges.The stiffness of the structure is relatively small,which will cause large wind-induced vibration under the wind loads.Meanwhile,the wind field at bridge sites shows complex distribution characteristics,which will directly affect the wind-induced response of the bridge structure.Taking a long-span cable-stayed bridge with a composite beam in mountainous area as the background of the study,the whole process calculation analysis including static wind stability analysis and buffeting time history analysis were carried out,and the influence of static wind additional attack angle and average wind speed distribution characteristics of static wind on the buffeting responses were studied.Then,the above analysis results of the buffeting responses were verified through the wind tunnel test of the full aeroelastic model,and the vibration suppression effect of the cable pulling measure in the buffeting responses during the construction of the cable-stayed bridge were studied.The main content and conclusions are as follows:1.Considering the characteristics of wind field in the mountainous area,the simulation program of the stochastic pulsating wind velocity field was compiled according to the principle of the harmonic synthesis method,and the correlation of the wind speed time history of the simulation points was tested.2.Taking into account the effect of aerostatic additional attack angles,the buffeting response analysis in time history was carried out.The comparison analysis shows that the additional attack angle of static wind had different effects on the buffeting responses,and will increase the buffeting displacement of the girders.3.The influence of different spanwise distributions of the average wind speed on the buffeting response was studied,and it was compared with the calculated value and the wind tunnel test data under the condition of uniform distribution of the average wind.It shows that the calculated results of the buffeting responses under the non-uniform distribution are larger than those obtained under the uniform distribution.4.In the construction stage of the largest single cantilever,six types of buffeting suppression measures were designed and their vibration suppression effects were verified based on the results of the full aeroelastic model test.The results show that the plane crossing scheme has a good vibration mitigation effect and is easy to implement in engineering,which provides a reference for the wind resistance of long-span cable-stayed bridges during the construction stages.