The Research On Aerodynamic Characteristics Of Main Beam In Continuous Rigid Frame Bridge Based On CFD

With the development of our country’s economic construction,the expressway has become an important part of the road network construction in mountain areas.Continuous rigid frame bridge is the preferred bridge type for highways crossing the high mountains.Its stiffness is small,the fundamental frequency is low,and the natural period is long,it is often designed as a double-bridge bridge or a double-track bridge parallel to the existing bridge to increase the vehicle capacity of the structure in engineering practice.There is often a certain degree of mutual influence between double decks under the action of airflow.From above,lower deck aerodynamic interference of twin deck girder of vortex induced vibration,flutter stability,buffeting response including upper and lower deck wind load difference and single girder cross-section,these effects are collectively referred to as "twin deck aerodynamic interference effect".Therefore,we must pay full attention to the role of wind loads.In this paper,the CFD numerical analysis method is used to study the aerodynamic characteristics of the main beam of a continuous rigid frame bridge with high piers and large span.The main work is as follows:Describing the control equation of incompressible fluid,discussing the principle and ideas of the flow field computation domain’s discrete method,the classification of turbulence numerical simulation and the turbulence calculation model,the selection of discrete difference format and the pressure-velocity coupling method are introduced in detail.Based on the computational fluid dynamics(CFD),a numerical simulation was performed with the background of a typical cross-section of a high-rise pier and large-span continuous rigid frame bridge.Introducing the dimensionless of aerostatic coefficients(resistance coefficient,lift coefficient,torque coefficient),to compare the influence of parameters such as wind angle of attack,beam height and bridge cross slope on the aerodynamic characteristics of the girder section of a single bridge.Aiming at the aerodynamic interference effect of the double bridge deck,the concept of aerodynamic interference factor was introduced.The influence of parameters such as the wind angle of attack and the relative position of the double-cross sections on the aerodynamic disturbance effects of the two-span bridges was compared,and the disturbance mechanism was analyzed based on the visualized flow field.The research results of this paper can be used to further study the aerodynamic interference effect of the two-axle bridges,and provide reference and guidance for the design of high-rise piers and large-span continuous rigid-frame bridges.