| As the bridge span was constantly refreshed, wind load on the bridge become more and more obvious. At the same time, in order to improve the traffic capacity of the bridge, there are two measures in the engineering: One is the construction of the twin deck bridge, through the horizontal space to increase the width of the bridge; The other is the construction of the double deck bridge, through the vertical space to increase the width of the bridge. For twin deck bridge, under the effect of wind, the upward and downward decks of these two kinds of bridges effect each other, so that the static force(three aerostatic coefficient) of the two decks bridge section caused by aerodynamic interference and dynamic action will be different from the single one, the phenomenon is called aerodynamic interference effect of twin deck bridge.In the known bridge wind resistance specification, there is no any recommendations or requirements for the three aerostatic coefficient of twin deck bridge, so the numerical simulation or the experiment have a higher value in engineering for aerodynamic interference effect problem of twin deck bridge.According to domestic and international research about Computing Wind Engineering(CWE), with the use of large-scale commercial computing software--Fluent, three aerostatic coefficient for aerodynamic interference effect of twin deck bridges study is simulated. Firstly,using SST k-? turbulence model by controlling the Y plus value of the near-wall grid processing, three aerostatic coefficient of single rectangular section is simulated, and compare the results of numerical simulations with wind tunnel test data and previous results, verified by comparing the numerical simulation method used aerodynamic interference effect of difference analysis is reliability. Applying for this method, single ?-shaped and streamlined section of three aerostatic coefficient is simulated for comparison to differences analysis of bridge aerodynamic interference effect.Secondly, we study the influence law of the bridge spacing ratio on the upward and downward section of the bridge. The results show that, when the upward section of the upper and lower symmetry, the drag coefficient of the upward section from the downward section have a greater impact on the ratio of distance to width(D/B) is 0.5. but when the upwardsection is streamlined, the drag coefficient is affected by the downward streamlined section to be significantly greater than its downward bluff body section(rectangular and ?-shaped section). When the upward section is ?-shaped section, at the ratio of distance to width(D/B)is less than 0.5, the downward section have a greater effect on the upward of the lift coefficient. With the increase of distance, the influence of upward section to the downward are weakened. For three aerostatic coefficient to the root of variance, there almost no effect on the downward section to the upward. Due to the influence of the trailing vortex formed in the upward section, the three aerostatic coefficient to the root of variance of the downward will appear larger fluctuations in the vicinity of D/B=1.Shielding factor of the drag coefficient, variation of the lift coefficient and lifting moment coefficient are defined, when the bridge spacing ratio constant, we study the upward section to the downward section about the aerodynamic interference effect law of the three aerostatic coefficient. The results indicate that, when the ratio of distance to width(D/B) is 1and the upper and lower symmetrical section, when the downward section is the same to the upward, the interference is minimum. at the ratio of distance to width(D/B) is 2 and 4, the interference of the upward ?-shaped section to the downward ?-shaped section is also minimum.The results of this study can provide reference for wind resistant design of bridges, has a certain value in engineering. |
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