Wind Resistance Analysis Of Cable-stayed Bridge Based On Numerical Simulation

Modern Bridges are developing in the direction of high flexibility and large span.It makes the bridge structure more and more sensitive to the wind load,which is easy to cause the damage of the bridge structure and even harm the safety of the bridge.In recent decades,long-span cable-stayed Bridges and low-tower cable-stayed Bridges have developed rapidly,so their wind resistance has become a research subject of great concern.In this paper,the research status of wind resistance of Bridges at home and abroad is reviewed.Based on the numerical simulation analysis method and taking Dalian Changshan Bridge as an example,a complete set of static wind stability analysis,pulsating wind buffeting analysis and vorticity induced vibration analysis framework is proposed.The main contents are as follows:1.The finite element model of the main bridge section of Changshan Bridge was established based on ANSYS,and different elements were used to simulate different components of the bridge.The static analysis,modal analysis and time history analysis of the main bridge model under the combined action of the first and second stage loads are carried out to verify the accuracy and effectiveness of the model.2.Based on fluid computing software(Computational fluid dynamics),The turbulence model-Spalart-Allmaras(S.P)is used to simulate the three component force coefficients of the typical beam cross section of the main span in the range of-10°～10°.3.Based on ANSYS,incremental and Newton-Rappsen methods are used to analyze the stability of the static wind of Changshan Bridge,and the displacement curve with wind speed and its unstable wind speed are obtained.Using the secondary development function of ANSYS APDL,the command flow module is stored in the macro,which simplifies the tedious process of multiple input.4.Based on the basic principle of harmonic synthesis method,MATLAB was used to write a program to simulate the pulsating wind field.According to Davenport chattering force model,the pulsating wind speed time history was converted into the pulsating dynamic time history.5.Through Gambit,the flow field of the bridge section was built and the grid was divided.The viv model was simplified to a vertical single-dof spring system.Runge-kuttta method was used to solve the dynamic equation iteratively,Motion transfer and grid update are carried out through CFD dynamic grid macro.The whole process from vortex generation to shedding in one period was captured,and the vortex shedding mechanism of the main beam section of changshan bridge was revealed.The disadvantageous wind speed and vortex shedding frequency that the bridge is prone to generate vortex-induced resonance are found,which can provide some reference for the evaluation of the wind resistance performance of the bridge.