The Strong Wind Characteristics At Bridge Site Of Trumpetshaped Topography With Wind Tunnel Test And CFD Simulation

The characteristics of wind field in mountainous terrain are complex,meanwhile the wind resistance of bridges has become a subject of great concern.There is very little information about wind effect in inland mountainous area,and the existing wind resistant code doesn't specify the characteristics of wind field.It is necessary to study the wind environment of this kind of special terrain so as to lay the foundation for the later wind load and structural response.Selecting the special bridge site of the Yellow River that is trumpet topography and discussing reasons for the formation of strong wind characteristics.By using uniform flow and B wind field to carry out the wind tunnel test,then the variation laws of the mean wind and fluctuating wind characteristic parameters are analyzed and compared.With the ANSYS-FLUENT module,selecting Realizable k-? turbulence model to simulate the flow field,wind velocity field and turbulent flow field.The results of the two methods are compared and analyzed.In the time,testing the difference of wind tunnel test and numerical simulation.It's synthetically evaluated the wind field distribution law of strong wind characteristics in the area of trumpet topography.Based on the data collected from the meteorological station near bridge site and the research results of relevant scholars,three methods to calculate the basic wind speed are summarized and put forward.The results show that due to the different wind direction and the location of measuring points,the mean wind and fluctuating wind characteristics have changed significantly.The calculated results are different from the existing codes.When the wind blows along the valley,the wind profile is consistent with the traditional model.Wind rose diagram shows that wind speed in the valley didn't form an acceleration effect.Most of the turbulence intensitydecreases with increasing height.In the horizontal direction,The fluctuating wind power spectrum where is the measured value is lower than the theoretical value in the low frequency range and higher in high frequency.In the vertical direction,the spectral frequency decreases with the increase of height.The velocity of uniform wind is greater than B wind field in wind tunnel test.But the turbulence intensity is slightly smaller.Compared with uniform wind,B wind field results is more closer to specification.Under the most unfavorable uniform flow field,the value of wind speed and turbulence intensity calculated by numerical simulation is less than wind tunnel test.After fitting the wind speed profile index by the least square method,it can be concluded that the surface area of the bridge site is B.Considering the partial safety,the basic wind speed calculated by the revised method of wind resistance is reasonable.