Study On The Influence Factors Of Static Wind Response Of Cable-Stayed Bridges In Construction State

In modern bridge construction,with the wide adoption of cable-stayed bridges and the increase of span,the displacement of bridges under static wind loads will increase significantly.Due to the small stiffness of the overall structure of cable-stayed bridges,especially in the construction stage,they are more sensitive to the wind action.As an important component of the cable-stayed bridge,pylon has an influence on the static wind response of the cable-stayed bridge in construction stage.Larger static wind response will not only cause static wind instability,but also change the stiffness characteristics of the structure,which will change the inherent dynamic characteristics of the bridge and thus the buffeting response is affected.In this thesis,a cable-stayed bridge was taken as an engineering example to study the influencing factors of the static wind response of cable-stayed bridge in construction state.The main research contents of this thesis are as follows:1.Section model wind tunnel tests were carried out on the girder section of the construction state of the cable-stayed bridge,and the aero-static three-component coefficients of the girder section model were measured at different wind attack angles and wind directions.Under skew wind,the measured results were compared with the results of Cosine Rule method and analyzed about the error margin.2.The wind tunnel test was carried out on the maximum double-cantilever construction state aeroelastic model of the cable-stayed bridge.The static wind response of the structure with pylon aerodynamic interference and without pylon aerodynamic interference was respectively measured in the turbulent flow field.At different wind speeds and under skew wind,the results figured out the main factors which have an influence on the static wind response of the cable-stayed bridge in construction state.3.The finite element software ANSYS was used to establish the model of the maximum double-cantilever construction state of the cable-stayed bridge.The linear and nonlinear calculation methods were adopted to calculate the aero-static force of the girder,and the results of wind loads were applied to the ANSYS model.The static wind responses were output from the simulation calculations.The results of all the different calculations were analyzed and also compared with the results of the wind tunnel test.The research indicates: The static wind load acting on the surface of the pylon will increase the static wind response of the girder;in the flow field,pylon will have a shelter effect on the incoming flow,which will cause the flow field near the pylon area to be changed,and this change will in turn affect the aero-static three-component coefficients of the girder under skew wind,thus the static wind response will change with the wind direction angle;the traditional Cosine Rule method of three-component coefficients was compared with another method section model test,and the error margin of Cosine Rule does exist;in finite element simulation calculations,the nonlinear calculation method of static wind loads will make the results more accurate and reliable.