A statistical approach to the identification of the two-dimensional aerodynamic admittance of streamlined bridge decks

The two-dimensional aerodynamic admittance function (2D AAF) is of great importance in the buffeting evaluation of slender, line-like structures. This paper aims to propose a simple and practical approach to identifying the 2D AAF of streamlined bridge decks. The effects of the aspect ratio (the ratio of span to width) and turbulence characteristics on the accuracy of buffeting loads calculated from the strip assumption were investigated. It was shown that both the aspect ratio and the integral length scale of turbulence play important roles in controlling the accuracy of the strip assumption. By increasing these two parameters, the 2D AAF of a streamlined bridge deck can be obtained within an acceptable error margin. Thus, for a section model with a large enough aspect ratio in an appropriate turbulent field, the 2D AAF of a streamlined bridge deck can be easily identified by the direct measurement of the velocity fluctuations and unsteady aerodynamic forces. The identification approach was validated through wind tunnel tests of streamlined bridge decks with three different aspect ratios in grid-generated turbulent flow. The proposed statistical approach can also be used for the identification of the 2D AAF of other slender, line-like structures.