Effects Of End Plates And Road Types On Transiting Test For Measuring The Aerodynamic Force Coefficients Of Structures

Wind load is one of the control loads in the design of structures such as high-rise buildings and long-span bridges.The current research methods of the wind resistance of the structures are mainly wind tunnel test,field measurement,theoretical analysis,and numerical simulation.Wind tunnel test is the dominant test method to study the wind resistance of the structures,and it is widely used.With the rapid development of the automotive industry and the highway,it is necessary to invest transiting test for measuring the aerodynamic coefficients of the structures using wind generated by a moving vehicle,which can make research methods of wind-resistance analyses rich.The transiting test can generate relative wind fields through vehicle motion.The structural model and the experimental facilities for the transiting test are affixed on the vehicle roof.Effects of end plates and road types on transiting test for measuring the aerodynamic force coefficients of structures are investigated.The background and significance of this study are illustrated at first.The wind tunnel test used for wind-resistance analyses of the structures are mainly introduce in this study.Considering transiting test as a new method,the optimum end plates and road types used for transiting test need to be determined.Then,the aerodynamic force coefficients of the prism model measured by the transiting test with various sizes and shapes of end plates are investigated.A total of 14 test conditions,in which the diameters of circular and square end plates D=0,3,4,6,8,9,10 times of the depth of the testing body,were performed three times.Comparative analysis of the wind tunnel and the transiting test results,the effect of end plates on the aerodynamic force coefficients,wind pressure coefficients,and pressure correlation coefficients of the model was investigated.The result indicated that the effect of end plates has a significant influence on the correlations of wind pressures.The pressure correlation coefficients in the same windward side increase,whereas the pressure correlation coefficients in the same leeward side decrease with increasing D/d(D: diameter or side length of end plates;d: depth of the model).The aerodynamic force coefficients curves of three repeated tests with various sizes of end plates have the same trend and agree well.The ratio of the diameter of the circular and square end plates to the height of the model should be 4?8 so as to ensure the 2D flow of the testing model in the transiting test.Finally,this study is based on the research of the second and third chapters,which analyzes the effect of road types on transiting test for measuring the aerodynamic coefficient of the model.After selecting circular end plates D/d=6?[4,8],a total of six test conditions under the condition of the temperature of 3 °C,the humidity of 42%,the natural wind speed of 0.28 m/s,straight line,the stable vehicle speed,no traffic flow,were performed three times.The results showed that in consideration of the factors of the turbulence intensity and pavement roughness,the results of the highway is most consistent with that of the wind tunnel test,the tunnel is the second and the viaduct is the worst.The drag force coefficients of the model in the transiting test without end plates were generally smaller while the drag force coefficients of the model with end plates were in agreement with that of the wind tunnel test.The transiting test should be conducted in the highway which meets the above-mentioned requirements and the end plates should be installed on two ends of the model.