Study On Wind-induced Cable Vibration Of Inclined Cable-stayed Bridges

In recent years, the application of the cables becomes more and moreextensive, because of setting up inclined cable-stayed bridges in great quantities.The cables are often used for pulling pieces. The strong wind-induced cablevibration becomes easily, because of its small quantity, just degree, damping.Therefore, The problems of wind-induced cable vibration have attracted more andmore experts,whose vibration mechanism is deeply studied in this paper, the maincontents includes following aspects.1. Achievements and primary study methods on some major topics arediscussed in detail. The tendency of wind-induced vibration of cablesmechanics development in the 21st century is also analyzed and suggested.2. To explain the phenomenon that cables in dry air are stable but theybecome oscillation of large amplitude, nonlinear equations ofnon-dimension for the coupled vibration of cables and an upper rivulet areconstructed with the use of the knowledge of elasticity and aerodynamics.The numerical computation is carried out by the Runge-Kutta method andthe time history curves and the amplitude-frequency curves are obtained.The primary analysis of the system's dynamic properties is given and theresults are shown that the rain-wind-induced vibration of cables is relatedwith wind velocity, yaw angle of wind velocity, the position of still rivulet,and air density.3. When any order natural frequency of bridge to the first natural frequencyof cable become the comparison relation, the cable also may produce thesignificant amplitude vibration. Nonlinear equations for the coupledvibration of cables and bridge are constructed. Through the numericalcomputation of the nonlinear equations constructed, the time historycurves and the amplitude-frequency curves of cables and bridge areobtained, when any order natural frequency of oscillation of bridge is inthe neighborhood of two or one times the first natural frequency ofcorresponding stayed cable. The results are shown that the resonanceamplitude value of the cable mainly is related with wind velocity, the ratioof any order natural frequency of bridge to the first natural frequency ofcable, the first natural frequency of cable, amplitude value of bridge whenthe beginning to start to move.4. The theoretical analysis is carried out by means of averaging methodwhen the ratio of any order natural frequency of bridge to the first orderfrequency of cable is two. According to the steady state solution of thefirst order approximation, the relationship between the resonanceamplitude of cables and frequency ratio and wind velocity, which makesthe coupled resonance mechanism of cables and bridge more clear. Theresults of analytical method are the same that show good agreement withthe numerical result.5. The bifurcation behaviors are discussed according to singularity theory.Many bifurcation models and transition sets are also obtained. Therelationship between the system parameter and the bifurcation behavior isconstituted, which supply the theoretical reference for designing andanalyzing the system.On the basis of the numerical computation and the theoretical analysis, anin-depth study is given to explain the rain-wind-induced vibration and the coupledresonance of cables and bridge. Numerical results, analytical results show goodagreement with each other.