Analysis Of Flutter Characteristics Of Suspension Bridge With Single-cable Plane

With the development of science and economy,more and more people pursue the enjoyment of beauty.Suspension bridge with single-cable plane becomes more and more popular among designers for its beautiful shape and gentle posture.Compared with the traditional suspension bridge,the damping and stiffness of suspension bridge with single-cable plane are further reduced.So the problem of flutter stability is more prominent.The flutter stability of suspension bridge with single-cable plane is a key problem that limits the span to be longer.In order to improve the flutter stability of suspension bridge with single-cable plane,this paper takes the bridge in Chongqing as an example.The flutter stability was studied from two aspects: the section form of the box girder and the arrangement form of the sling cable.It can be used as a reference for the aerodynamic selection of box girder and the arrangement of sling cable.The main work of this paper is as follows:1、The theoretical basis of the theory of flutter analysis was reviewed and summarized.The two-dimensional flutter analysis with two degrees of freedom and the identification method of flutter derivative was introduced emphatically.It laid a theoretical foundation for the later research.2、The forced vibration wind tunnel of ideal thin plate was simulated by FLUENT hydrodynamic analysis software.Date of aerodynamic time-history curve can be extracted by forcing the model to do pure vertical and pure torsional motion.In order to identify the flutter Derivatives,program was written on the basis of least Squares.The result shows that the solution is in good agreement with the Theodorsen theoretical solution.It verifies the reliability of the numerical simulation and flutter derivative solving program.3、Supported by the bridge in Chongqing,by using numerical wind tunnel simulation method,flutter derivatives of closed box girder section with 0%,20%,40% slot width ratio was calculated.Comparing the flutter derivatives with theoretical values of Theodorsen,It shows that trends of all flutter derivatives are in good agreement with theoretical values of Theodorsen.Considering that A1*,A2*,H3* and aerodynamic damping of A,D determine flutter stability of convective box girder section,variations of those factors were compared with the changes of slot width.Thus,the cross section of optimal aerodynamic performance is selected.The result shows that aerodynamic performance of the section with 40% slot width behaves the best.Aerodynamic performance of the section with 20% slot width behaves the better.Aerodynamic performance of the section with 0% slot width behaves the worst.4、Still relying on the bridge in chongqing,the model of the bridge was built by using Midas finite element analysis software.Changing the cross slant slings into single straight slings,the new bridge was built.The influence of slant slings on the stiffness was studied by comparing dynamic characteristics of the two bridge.And then,based on stiffness driving principle,The flutter critical wind speed of the two single cable plane suspension bridges was compared according to the existing formula of flutter critical wind speed.The effect of slant sling on flutter stability of suspension bridge with single-cable plane is analyzed.The result shows that slant sling can improve the flutter stability of suspension bridge with single-cable plane.