Numerical Study On Aerodynamic Interference Effects Of Twin-deck Blunt Box Girder

As the sharply rapid development of the northwest regional economy andtransportation, twin-deck continuous rigid frame bridges get the more favor of the designerin design. And in the northwest region, bridges pass through the deep valley and loess gullregion, which is seriously influenced by the wind.Continuous rigid frame bridges are morelikely to use blunt box section. Compared with the streamlined box girder and truss girderbridge, the blunt box girder is easier to be influenced by the aerodynamic interferenceespecially twin-deck bridge. So it has practical significance to study of aerodynamiccoefficient between blunt body box section.In this paper, based on a typical twin-deck continuous rigid frame bridge located in thenorthwest of China, use the method of numerical simulation to calculate the aerostaticcoefficients of each control section, and translate the aerostatic coefficients into interferencefactor to analyze the aerodynamic interference effects. Analysis results: double bridgeupstream and downstream especially downstream bridge relative the single deck has theobvious aerodynamic interference effect. When the girder width is certain, for single bridgethe drag coefficient decreases with the increase of height, while the lift coefficient and thetorque coefficient have no variation law. For twin-deck bridge, as the section heightincreases, the interference effect of the drag coefficient is obvious, but the variation law ofthe lift coefficient and the torque coefficient is not obvious. Relative to the single section,the downstream generally has more apparent interference effect. Therefore in blunt bodybox cross section continuous rigid frame bridge design, aerodynamic interference effectbetween twin-deck girder should not be neglected. The specific research and analysis of theinterference effect between the typical section must be conducted in design.On the basis of calculation results, this paper uses the pressure measuring method to getthe distribution of the section mean pressure coefficient and the root of variance. Spectrumanalysis for the key point, combine with the stress contour and vorticity graph from themicro level to explain the aerodynamic interference effect between the twin-deck bridge.