Experimental Study On Spanwise Correlations Of Vortex-induced Forces Of A Rectangular Cylinder

The vortex-induced vibrations of maindecks of bridges have notablethree-dimensional characteristics; and the vortex-induced forces (VIFs) of themaindecks are not synchronization in spanwise direction. Due to the inad e-quate research of VIFs spanwise correlations, the VIFs of maindecks are stilltaken as fully correlated in spanwise during the wind-resistant design ofbridges. With the increase of bridge span and the decrease of structure weight,to study the spanwise correlation of the vortex-induced force of bridge decksbecomes more and more urgent and necessary. Considering the complexity ofactual bridge sections, current researches of the spanwise correlation of thevortex-induced force mainly concentrated in some rectangular a nd plate sec-tions. As a bluff body of the rectangular cylinder with an aspect ratio of5:1, aresearch of it can provide more useful information for other sections in spiteof its simple geometry. In this paper, the spanwise correlation of the vortex-induced forces of the5:1rectangular cylin der was studied by the model test sin wind tunnel. The pressures distributions of the cylinder were also analyzedfrom the micro perspective. The2D numerical simulations of vortex-inducedvibratins of the rectangular section were conducted with CFD methods. Andthe3D numerical simulations were conducted for the stationary cylinder. Theresults of numerical simulations and experiments were compared with eachother. Brief introductions to the main contents of this paper are as follows:1. A brief overview of the VIV and the spanwise correlation of the vortex-induced forces and the main research contents of this p aper were given in thefirst chapter.2. The model of the5:1rectangular cylinder were designed and made. Thearrangement of the pressure taps and the wake velocity measuring points wereintroduced in details. The different test systems and test cases were also intro-duced.3. The experiments of VIFs spanwise correlations were conducted insmooth and turbulent fl ow separately. The spanwise correlation of vortex-induced forces and wake velocities of the stationary and oscillating rectangu-lar cylinder were analyzed. The effects of the amplitudes and turbulence on the spanwise correltions of VIFs were also investigat ed. The regular of themodel’s surface pressures distributions and the cross-correlation of upper andlower lift coefficient were investigated to analyze the influence of the ampl i-tudes and turbulence on the pressures and spanwise correlations. The parame-ter identification methods for three kinds of vortex shedding force modelswere introduced briefly, and then the parameters of VIFs were identifiedthrough the experimental results.4. The numerical simulations of flow around the stationary and oscillate-ing rectangular cylinder with aspect ratio of5were conducted. The model sur-face pressures distributions were also studied. The correlation of aerodynamicforces and the law of the surface pressures distributions were analyzed by3Dnumerical simulations of rectangular cylinder. Then, the two-dimensional,three-dimensional calculation results and the experiments results were com-pared.