Study On Aerodynamic Parameters And Time-domain Buffeting Analysis Of Long-span Steel Truss Suspension Bridge

As one of the "new big four inventions" in modern China,high-speed rail which has solemn become one of the most beautiful business cards is shown to the foreign countries.The railway bridge is an important part of the high-speed railway,especially when crossing the big rivers,building long-span bridges is essential.Among them,the truss girder is the main girder of long-span railway cable-stayed bridge and suspension bridge,which has the advantages of structure stable,high safety factor and double decks.However,there are many bars for truss structures and how to accurately build model in numerical simulation is difficult to solve.Therefore,it is necessary to study them.The aerodynamic admittance is the key factor in the precision analysis of bridge buffeting.Previous studies on aerodynamic admittance of truss usually based on wind tunnel test and study by numerical wind tunnel has not been reported,so it is necessary to do some exploration.In wind vibration studies,although buffeting can not lead to a bridge crash,it has an adverse effect on the bridge's durability and the comfort of the vehicle.In this thesis,a long-span railway suspension bridge is taken as a project and simulate the wind environment at the bridge site.Next,aerodynamic parameters of truss girder are studied by wind tunnel test and numerical simulation.Finally,time domain analysis of buffeting is used in service stage.First of all,combined with the characteristics of the wind field at the bridge site,the threedimensional numerical simulation of the wind field is carried out on the main girder,main girder and bridge tower by harmonic synthesis.Then,the wind tunnel test of rigid segment model is carried out on the main girder,and the static third component coefficient is obtained.At the same time,the two-dimensional numerical model of the main girder with different positions of the webs is established by using the contour and real-area ratio not changing as the control conditions.The three-component force coefficient is obtained from the numerical wind tunnel and compared with the wind tunnel test data to obtain the two-dimensional equivalent model.Then based on the twodimensional equivalent model,a single-frequency harmonic pulsating wind field is generated by using FLUENT's UDF program,and its dynamic admittance is identified.Finally,the finite element model of full bridge is established by ANSYS,and its dynamic characteristics are calculated and analyzed.Through calculating the static wind and buffeting response,the influence of the fluctuating wind on the bridge is analyzed.In addition,the effect of the aerodynamic admittance on the displacement response of the structure is also studied.