Numerical Simulation Of Wind Environment In Mountain Regions And Buffing Response Analysis For Arch Bridge By Virtual Pseudo Excitation Method

Many regions of western China are mountainous or hilly.In order to meet the need of economic development in those regions,a lot of bridges are built in the mountainous regions.As increasing bridge span,wind-causing buffeting is far more prominent in these bridges,and therefore it’s crucial to have an accurate wind environment description in complex mountainous or hilly regions.Due to lacking of meteorological data and complex geographical feature,it’s difficult to design wind parameter though ascertaining norm so that it’s necessary to do a 3D data simulation for mountainous area wind environment.In research on wind-causing buffeting,buffeting response analysis plays a key role in safety assessment for bridge’s wind resistance.Too many buffeting responses affect safety and stability when bridge is put into operation.As one of frequency domain methods which is highly accurate and is used to solve structural random buffeting response,pseudo excitation method is easy to realize by programming,and it’s applied widely in buffeting analysis field.A large-span arch bridge in west mountainous area is selected as the research background.The CFD numerical wind tunnel is also utilized to do a simulated 3D geographical data calculation on wind parameter of the selected bridge.According to simulated wind parameter result,buffeting response analysis is carried out on the selected bridge by finite-element software based on pseudo excitation method.First of all,the development of arch bride in China and foreign nations is looked back,and the research status of numerical simulation of wind environment and bridge buffeting response analysis in mountainous regions are interpreted in the thesis.Then,the test approach and data simulation approach of both researches are summarized and the feature of atmosphere boundary-level wind as well as relevant theory of wind load calculation is featured.Then,CFD is applied to wind parameter numeric simulation at the bridge area.The boundary of the bridge location is expanded in the form of circular curve and cosine curve.Self-programmed UDF function is applied in inlet wind velocity profile and turbulence strength profile.SSTk-ω model is chosen from FLUENT to solve the flow,and wind parameter simulated calculation result is extracted and discussed.Finally,the formulas of pseudo excitation theory and bridge buffeting response theory is combined,and a pseudo excitation calculation formula of multiple dimensions and multiple points buffeting response is deduced.This process is realized by the finite element software.After the infinite element model of bridge is established,the pseudo excitation load vectors are built according to the data of wind tunnel section model,then the buffeting response computing of completed stage and most unfavorable status during construction are carried out and the response results are extracted.Through the comparative analysis of the buffeting response results of different structural states and different wind speed values,some conclusions for the engineering project are obtained.