ورود آیرودینامیکی سه بعدی پل های ورقه ای جعبه ای
Abstract
1- Introduction
2- Measurements of incident turbulence and fluctuating pressure
3- Three-dimensional aerodynamic admittance function (3D-AAF) of the bridge decks
4- Conclusions
References
Abstract
Via wind tunnel tests, the fluctuating pressures on the surfaces of three streamlined box bridge models are measured in two turbulent flow-fields with different turbulence characteristic parameters. The distributions of the fluctuating pressures on the models are presented and discussed in detail. The correlations between the fluctuating pressures on a crosswise section and the coherences of the buffeting force along the spanwise direction of the models are investigated. Furthermore, the 3D aerodynamic admittances of the models are identified and analyzed. An empirical formula for determining the 3D aerodynamic admittance of a streamlined bridge deck is proposed based on the extensive results of the experimental data and analysis. Clarifications are made regarding the differences between the real 3D aerodynamic admittances and the existing formulas. It is then further revealed that the real value of a 3D aerodynamic admittance is not between 1 and the number determined by the Sears function. This is followed by a rational explanation for the observations based on the experimental results.
Conclusions
Extensive wind tunnel tests were conducted to measure the fluctuating pressures on the surfaces of three streamlined box bridge models in two turbulent flow-fields with different free-stream turbulence characteristic parameters. The distributions of fluctuating pressures on the models, the correlations of fluctuating pressures on crosswise sections and the coherences of the buffeting force along the spanwise direction of the models were presented and discussed. An empirical formula for determining the 3D aerodynamic admittances of streamlined bridge decks was proposed based on the results of the experimental data and analysis, which was verified to be an accurate aerodynamic admittance model for the simulation of the buffeting loads acting on bridges. Based on a detailed analysis of the measured data and comparative studies, conclusions are summarized as follows: • The aerodynamic forces acting on bridges have strong 3D features; the existing aerodynamic admittance models based on the strip assumption may not be able to accurately simulate the buffeting forces on bridge decks. • The aerodynamic admittance of a bridge deck is affected by the coherence of the fluctuating pressures on a crosswise section and the buffeting forces along the spanwise direction. Therefore, a reasonable 3D-AAF should be a function of reduced frequency Lw and structural characteristic width B.