Influence of Wind Turbulence on Aerodynamic Admittances of a Streamlined Bridge Deck at Different Angles of Attack

Abstract

This study revisits the modeling of buffeting forces on bridge decks and establishes the relationship between one- and two-wavenumber admittances, and between the spanwise coherence functions of turbulence and buffeting forces. The two-wavenumber admittance of the lift of a thin, flat plate section caused by vertical turbulence is then used to investigate the three-dimensionality effect of turbulence on integrated buffeting lift of a finite length. To investigate the characteristics of two-wavenumber admittance of bridge deck sections, synchronous pressure distributions of a streamlined bridge deck are measured and characterized in a wind tunnel at three different turbulent flows and several angles of attack. The means and standard deviations of surface pressure coefficients and integrated drag, lift and moment coefficients, the power spectra, spanwise correlation, and coherence of turbulence and buffeting forces are analyzed, from which the two-wavenumber admittances of drag, lift, and moments are determined. The effects of integral length scale and intensity of turbulence and angle of attack on static force coefficients and admittances are characterized. Finally, the three-dimensionality effect of turbulence on integrated buffeting forces and responses of long span bridges are investigated using the measured two-wavenumber admittances. The results of this study highlight the importance of appropriate simulation of large-scale turbulence in wind tunnel for characterizing static force coefficients and admittances of bridge deck sections, and for estimation of buffeting responses of long-span bridges.