Influence Of Test Vehicle Type On The Static Aerodynamic Coefficients Of Structures Measured By Transiting Test

The structural static aerodynamic coefficient is an important parameter for preventing structural wind-induced disasters and optimizing the wind-resistant performance of the structure.It is widely used in the research,design and manufacture of wind-resistant structures in various fields.At present,the methods of studying the aerodynamic coefficient of structures mainly include wind tunnel test,field measurement,theoretical analysis and numerical simulation,while the transiting test has low cost,no blocking effect,and is simple and easy to implement,which can provide a new test method for the study of structural static aerodynamic coefficient.The characteristics of different types of test vehicle will affect the measurement results of the transiting test.Therefore,studying the influence of the test vehicle types on the measurement of the structural static aerodynamic coefficient by the transiting test method will provide a reference for the selection of the test vehicle type in the subsequent transiting test.Therefore,this paper takes the CAARC standard building model and the triangular prism segment model as the test objects to study the influence of the test vehicle type on the along-wind,crosswind and vertical aerodynamic performance of the structure on a straight and flat expressway with good weather.The experimental results are based on the wind tunnel test results,and the test vehicle types applicable to the transiting test method are summarized.Firstly,the influence of the test vehicle type on the along-wind aerodynamic performance of the structure is studied.In the test,the standard building model and the triangular prism segment model were used as the research objects to study the influence of the test vehicle type on the mean wind pressure coefficient,fluctuating wind pressure coefficient,drag coefficient and fluctuating drag coefficient in the along-wind direction of the structure.Flow field simulation result shown that the along-wind vibration of the structure causes the windward and leeward sides of the structure to form vortex structure,which in turn affects the along-wind aerodynamic performance of the structure.Secondly,the influence of the test vehicle type on the vertical aerodynamic performance of the structure is studied.In the test,the triangular prism segment model was taken as the research object,and the influence of the test vehicle type on the vertical mean wind pressure coefficient,fluctuating wind pressure coefficient,lift coefficient and fluctuating lift coefficient of the structure was studied.The test result shown that the fluctuating wind pressure coefficient of the vertical bottom surface of the triangular prism model measured by different types of test vehicles tends to a stable value when the incoming wind speed exceeds 85 km/h.Flow field simulation result shown that the vertical vibration of the structure changes the vortex shedding on the bottom surface of the structure,which affects the vertical aerodynamic performance of the structure.Then,the influence of the test vehicle type on the aerodynamic performance of the structure in the crosswind direction is studied.In the test,the standard building model was used as the research object to study the influence of the test vehicle type on the mean wind pressure coefficient,fluctuating wind pressure coefficient and wind pressure correlation coefficient in the cross-wind direction of the structure.The test result shown that the smaller the root mean square of the vibration acceleration of the structure in the transverse wind direction measured by the test vehicle,the stronger the correlation between the measurement points in the transverse wind direction and the typical measurement points.Flow field simulation results shown that the crosswind vibration of the structure affects the crosswind vortex shedding and the along-wind leeward wake.The change of the crosswind vortex shedding directly affects the crosswind aerodynamic performance of the structure.Finally,the test results of the above three aspects show that the absolute error of the measured structural static aerodynamic coefficient of the car and SUV is less than5.00% compared with the test results of the wind tunnel test.Compared with the wind tunnel test results,the absolute errors of the measured along-wind drag coefficients of pickup and large vehicle are less than 5.00% and 15.00%,respectively.Compared with the wind tunnel test results,the absolute error of the vertical lift coefficient of the triangular prism model measured by pickup and large vehicle exceed 20%.Car and SUV have negligible effects on the aerodynamic performance accuracy of the structure,and are suitable for transiting test.Pickup and large vehicle can be used for transiting test,but relevant measures need to be taken to improve the accuracy of test results.