Selection And Numerical Analysis The Stiffening Girder Section Of Pneumatic In Mountain Narrow Suspension Bridge

The geometrical nonlinear characteristics of large span suspension bridge is determined by its structure is easy to live load effects, such as the lane load, wind load and dynamic load. Therefore, for the long-span bridge structure, dynamic performance analysis is necessary, is also a key step in design. Located in the Gansu province Yongjing County Liujiaxia bridge as the engineering background, the dynamic analysis of the bridge decks, in the previous research work, is based on the theoretical analysis, the use of wind tunnel test and numerical simulation method of finite element on the girder bridge aerodynamic performance analysis of local to the whole. There are the main conclusions:(1) Summary of the wind tunnel test data of Liujiaxia bridge girder stiffener, changes of the three component coefficients obtained with reduced wind velocity and 8 aerodynamic derivatives, and provide conditions for the numerical analysis of the back. Through the wind tunnel model test determination of aerostatic coefficients, the plot graph of tri component force coefficient with the change of wind attack angle, and analysis of aerodynamic r elations between tri component force coefficient and aerodynamic stability, to through the bridge of different sections of the aerostatic coefficients, the flutter stability were rapid evaluation and determine. The aerodynamic parameters of the bridge deck have important significance for bridge design selection, as well as the safety and economy of bridge structure.(2) In order to better illustrate the bridge deck aerodynamic performance of steel box girder of the selection, selection of cross section of main girder bridge with similar size in the Liu Jiaxia bridge girder sections existing, the beam width 15.6m, height 2m. The establishment of the girder section Aerodynamic Numerical Model by using the CFD method of Midas FEA, on the geometric similar conditions, given the same boundary conditions and analysis conditions, the aerodynamic performance of the pros and cons of section. The pressure field distribution from the three component coefficients extraction and change over time, the comprehensive analysis and comparison, steel truss stiffening girder section aerodynamic performance is better than the steel box girder.(3) Only from the stiffening girder segment section Aerodynamic Numerical simulation is given to illustrate the performance of the suspension bridge wind resistance is partial, incomplete. Therefore the establishment of suspension bridge three-dimensional finite element dynamic model, two different types of stiffening girder to bridge structure, add boundary conditions, analysis of the overall working set, the wind resistance performance of suspension bridge calculation and analysis, to extract the first six order vibration mode. Selection of bridge in middle span stiffening girder as the research object, analysis in the process of wind speed the step loading, the girder vertical, lateral and torsional displacement, and the curve listed. In the overall analysis of bridge that, combined with the structure characteristics of Liujiaxia bridge, two kinds of main girders of suspension bridge can me et the requirements of the wind, but the wind resistance performance of steel truss stiffening girder section of a stronger, more suitable for the characteristics of Liujiaxia bridge.(4) In the numerical simulation of bridge deck aerodynamic calculation, only the Midas FEA finite element analysis of two dimensional CFD, and steel truss stiffening girder is a member of non closed beam, dynamic performance to the exact, precise simulation of the main beam in the wind environment in the air, a three-dimensional space model needs. At present in the ANSYS in the simulation of Workbench, FLOTRAN and other modules can make the air flow field, also has the very good practical application in the field of engineering.In the analysis of the data was considered for long span suspension bridge structure mechanical characteristics and Liujiaxia bridge location, seasonal climate. Combined with the structure characteristics of the Northwest’s first bridge is a long-span bridge, the most narrow, the first use of large diameter steel pipe concrete pylon components such as unique.