3D Aerodynamic Admittance Research Of Streamlined Box Bridge Decks

In this paper reviews have been made on the status quo and problems of buffeting analysis on long span bridges. While in buffeting analysis, what's of vital importance is the aerodynamic admittance, which also plays an important role in elaborate buffeting analysis of bridges in future. Method combined wind-tunnel test with theoretical analysis has been incorporated in this thesis, which has presented fruitful achievements from elaborate and profound researches done on the aerodynamic admittance of the streamlined girder section of long span bridges. In summary, following six aspects have been covered in context:1. Firstly history of researches on the aerodynamic admittance has been looked backward to, and then status quo and studies in future have been quoted and analyzed. On the basis of fruits produced by forthgoers in this field, Important points have been made that that aerodynamic admittance bridges turbulence wind spectral and buffeting-force spectral. Furthermore, judgement has been made that aerodynamic admittance of streamline girder section features a characteristics of three dimension (3D), which then enlightens that 3D aerodynamic admittance modal is of preferential option to simulate the buffeting loads of long span bridges accurately.2. Two turbulent wind fields with different turbulent scales have been stimulated in wind tunnel, and then characteristics of turbulence is analyzed.3. Impulsive pressures on top of a flat plate and two streamlined girder sections have been investigated by independently-developed synchronies manometer system with 60 channels. And then distributions of mean pressure, static coefficients, distributions of impulsive pressures and curves of time domain and frequency domain of impulsive loads are obtained.4. According to theory on 3D aerodynamic admittance, aerodynamic admittances of plate and two streamlined girder sections have been identified. And the empirical formula for obtaining the 3D aerodynamic admittance of streamline girder section has been deduced. Clarifications have been made on the differences between 3D aerodynamic admittance and Sears function, and then further important outcomes have been brought out that the numeric value of 3D aerodynamic admittance is not between 1 and the Sears function followed with a rational explanation on it from experiments. 5. The correlation of impulsive aerodynamic force of streamlined girder sections along the span has also been studied. And it has been pointed out that the correlation of impulsive aerodynamic force is much more significant than that of impulsive wind velocity, which would results in unsafety if the correlation of impulsive wind velocity takes place of the correlation of impulsive aerodynamic forces during analysis.6. Based on 3D aerodynamic admittance function, the buffeting analysis method in frequency domain for long span bridges has been developed. And analysis has proved that satisfactory outcomes on buffeting response to long span bridges would be obtained with the 3D aerodynamic admittance model.