The Simulation Of Wind Loads And Buffeting Analysis During Construction For Long-Span Cable-Stayed Bridge

With the vigorous development of the transportation industry, the construction of long-span bridges also entered the golden period of development. However, the increase of the span makes the structure more flexible, the sensitivity of the bridge structure to the wind load is also increased. Therefore, the vibration of long-span bridges for wind load has become a problem urgently solved. At present, the research for bridge wind resistant content is mainly caused bridge study on wind-induced vibration and wind load on bridge wind vibration, based on forth Aojiang bridge,respectively simulated three component coefficient and fluctrating wind field on the bridge, and chattering buffeting analysis during construction for bridge.The main work and conclusions are as follows:(1) According to forth Aojiang bridge section parameters, the numerical simulation of three component coefficients for sections of the bridge were conducted.the values of drag coefficient compare to the "highway bridges standard" JTG/T D60-01-2004 specified values. The results show that the code is relatively conservative.(2) For Studying the influence of aerodynamic measures and ancillary facilities on the three component coefficients,Design the three forms of section—angle of the wind mouth, the central slot and additional ancillary facilities. The numerical simulation three component coefficients by means of CFD method.The simulation results show that set wind mouth reduces the drag coefficient of girder section.But the Change slope of lift coefficient and moment coefficient is increasing. The drag coefficient is increasing with increase of rate slotted.The trend of change is slowly. The sensitivity of the three component coefficients to wind attack angle is reduced. When the auxiliary facilities are added, the drag coefficient decreases obviously, the lift coefficient changes slope increases, and the slope of the coefficient of lift torque decreases. By observing the distribution of the flow field around the main girder section, it is found that the high wind speed is appeared at the bottom of the main beam. Therefore, it is needed to increase the flow guiding measures to avoid the damage of bridge structure.(3) The cut off frequency is discussed for Simulation accuracy.The greater the value of the cut-off frequency, the more wind speed spectrum contains energy and the simulation precision is better.The vertical velocity spectrum is highly sensitive to the wind speed and spatial height. The lower the height,the greater the cut off frequency. The random wind field of large span cable stayed bridge is simulated by harmonic superposition method. The comparison between the simulated fluctuating wind power spectrum and the target spectrum is conducted. The results show that there are good agreements between the simulated power spectrum and the validity of result is also proved.(4)Establish three-dimensional finite element model of fourth Aojiang bridge by ANSYS,conduct buffeting analysis of the construction stage. The internal force is maximum in the tower and beam combination.The buffeting response of bridge is close to the static wind response. The influence of the self excitation force on the buffet response is larger, and When the wind resistance design is carried out, the chattering response result from the self-excited forces is slightly conservative.