| Field measurement is the most direct way to study the mechanism of structure wind loading and the structural dynamic response,and the result of the field measurement can be used to modify the existing test methods and theoretical model.The field measurement mainly monitors the structural displacement,acceleration and the wind velocity in typhon weather through GPS,acceleration device and the anemometer.Field measurement is a basic work,which usually lasts from several years to ten years or even.Wind field measurement is important in field measurement,and the anemometer used for wind field measurement works by exposure to the air,and most anemometers are installed on the top of high-rise buildings and are highly affected by the strong wind,especially the thunder,therefore,the anemometer damages frequently.Based on the study of the aerodynamic force of the two-dimensional blunt body structure,a new scheme has been put forward to measure wind speed.The scheme fulfills wind speed measurement by transforming the aerodynamic force of the two-dimensional blunt body measured by four micro differential pressure sensors,and the feasibility of the scheme has been proven by a serial of wind tunnel test.The main works of this paper are as follows:(1)Pneumatic-averaged method has been applied to study average aerodynamic force,root-mean-square aerodynamic force and aerodynamic force of two-dimensional square cylinder,and compared the mean value,the mean square value of aerodynamic force and power spectra density function of aerodynamic force of two-dimensional square cylinder,and it is compared with the result of point-by-point synchronous pressure measurement method,and it turns out that pneumatic-averaged method can be directly used to measure aerodynamic force of two-dimensional square cylinder,thus the number of pressure sensor required can be greatly reduced.(2)Experiments have been conducted on two-dimensional square cylinder with a single layer pressure tap.Analysis curves that the dimensionless aerodynamic force coefficient(defined respectively as the ratio of two principle x,y direction aerodynamic force to the resultant force)changes along with wind direction and it is found that curves are monotonic on the wind direction interval 20~70° and are insensitivity to wind speed and turbulence intensity.Based on the conclusion,a two-dimensional square cylinder that is made of two 45° staggered principle axis and stacked square cylinder has been designed and a more detailed wind tunnel tests have been carried out.A comprehensive analysis of the data yields quantitative change rule about the dimensionless aerodynamic force coefficient of the double layer two-dimensional square cylinder changes along with the wind direction and fulfills accurate identification of wind direction.According to the solved wind direction and the wind tunnel test result of drag coefficient,the wind speed can be further solved.(3)It is further discussed about aerodynamic admittance function under different wind direction,according to the comprehensive analysis of test data,an aerodynamic admittance function changing with different wind direction about the test objection.Consequently,wind power spectra density function can be calculated from power spectra density function of along wind aerodynamic drag force,thus turbulence intensity can be solved.The wind speed measurement scheme proposed above doesn’t have rotating components and it’s sensor circuit is protected from the bad lightening environment with insulating electric tubing connecting pressure taps and sensors,which greatly improve the reliability of the wind speed measurement device,and it has a very important reference value for field measurement of wind effect of high-rise buildings in wind resistant research. |
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