The Study On Static And Dynamic Nonlinear Theoretical Model And Test Of Cable

With the rapid increment of the span of cable-stayed bridge,the length of stayed cable also increases obviously. The stayed cable is one of the principal force members of cable-stayed bridges. The stayed cable would be prone to exhibit vibration of large amplitude on the action of wind, earthquake and traffic load, so it reduces the life of stayed cable even caused destruction. The accurate analysis of both the static and dynamic is very important for the design of cables in cable-stayed bridges. So we need to do deeply research on static configuration and dynamic features in order to make solid foundation in the design of cable-stayed bridges and vibration control.The main points of this paper are as follows:(1) Based on static configuration of the traditional catenary, a more accurate static expression is derived considering axial stiffness and a numerical analysis is performed. A model of stayed cable is built in the laboratory. Static configuration of stayed cable is analyzed under different cable force,the stayed cable parameters are substituted into catenary expression and the expression considering axial stiffness. Then static configuration curves are provided through two expressions, and compared with the model curve tested in test room.(2) First,the vibration character of stayed cable is analyzed considering the geometrical non-linearity including gravitational sagging and the initial tension.Based on the parabola and catenary theories,the transverse vibration analytical solutions is derived.Then,the nonlinear dynamic equation of equilibrium in plane is established.The nonlinear equation is simplified and decouped by used the Galerkin method.Take the long and mid-long cable of the span of cable-stayed bridges longer than 1000m for example,the data of theoretical calculation and prototype simulation has done a comparative analysis.Nonlinear dynamic test of stayed cable is made,and make compare the theory with the experimental results.(3) Based on the 3th chapter, the nonlinear dynamic equation of equilibrium in plane is simplified,eliminate the couping if quadratic nonlinear term through self-variable transformation.Thus,a duffing equation similar to the soft spring vibration is obtained. Melnikov method are proposed for making qualitative analysis in the arisen conditions of Hamiltonian system.