Research On Aerodynamic Impacts Of Snow On Bridge Decks

It is obviously known that snowdrift has become a spot in research at present.In this paper, the research quo of snowdrift and problems existing in the process studying it is reviewed.Two-dimensional distribution of snow on bridge deck is analyzed by FLUENT and then the study is focused on the effects of snow on flutter derivatives, vortex-induced vibration by wind tunnel test.The concrete contents and results are as follows:1.Gambit is used to model and mesh the regions and FLUENT to simulate the snow shapes on the bridge deck of a cable-stayed bridge with streamlined steel box girder. The results show that the wall friction velocity is closely contacted with the deposition or erosion of snow.The amount of snow erosion on the leeward is smaller than that on the windward and it reaches minimum in the wake of the bridge.2.The influence of snow on the three component coefficients of the beam is studied by wind tunnel test.The slopes of lift coefficient and torque coefficient curve become bigger and increase about 40%.Also,the resistance coefficient increases about 15% and the tendency of the curve of the three component coefficients is almost the same.3.The influence of snow on the vortex-induced vibration is also analyzed by wind tunnel test.The results show that vertical vortex induced vibration of girder disappeared at the wind attack angle of+3° because of the effects of snow and that the influences are the same under the condition of three different wind speeds.4.Through the wind tunnel test,it reaches that snow has some influences on flutter derivatives of the beam.With the influence of snow, the effect of pneumatic inertia and aerodynamic stiffness which is caused by the vertical movement displacement on self-excited lift and self-excited torque changes from negative to positive;the contribution of pneumatic inertia and aerodynamic stiffness which is caused by torsional motion displacement to self-excited lift and self-excited torque decreases and the impact is relatively larger when the wind velocity is 20 m/s;the effect of aerodynamic damping which is caused by torsional motion velocity on self-excited lift becomes negatives when the reduced velocity is about 2.