Temperature Effects On Linear And Nonlinear Vibration Characteristics Of Suspended Cables

Suspended cables are widely used in bridge structure and large-span buildings because of its reasonable force,material saving,fast construction and colorful modeling.However,cables are highly susceptible to temperature changes due to long-term exposure to the natural environment.The effect of temperature variation on the vibration characteristics of the cable is comparable to that of damage and excitation.Therefore,it is urgent to study the effect of temperature change on the vibration characteristics of suspended cables.The main work of this article is as follows:(1)The effect of temperature change on the linear vibration characteristics of the suspended cable was studied.Considering the effect of temperature change on the initial configuration of suspended cables,dimensionless parameters reflecting the effect of temperature change are introduced,and the equation of motion of suspended cables under thermal stress is established.The changes of modal frequencies of the cables with different Irvine parameters under temperature changes are analyzed,and the effects of mode shapes on temperature changes are also studied.Studies have shown that the relationship between temperature change and frequency is closely related to the Irvine parameter.The effect of temperature changes on the symmetric mode shape is also related to the Irvine parameter.But it is negligible to the antisymmetric mode shape;(2)The effect of temperature change on the super / subharmonic resonance characteristics of the suspension cable was studied.By using Hamilton's principle,the in-plane nonlinear motion equations of the suspended cable are obtained.Galerkin procedure is used to obtain the discrete ordinary differential equations.Using the multi-scale method,the amplitude-frequency response equation of the super-harmonic and sub-harmonic resonance response is obtained,and the first-order approximate solution of the motion equation is obtained.Through the amplitude-frequency response curve,time-history curve and phase diagram,the influence of temperature changes on the superharmonic and subharmonic resonance characteristics of the suspended cable is analyzed.Studies have shown that temperature changes can cause significant qualitative and quantitative changes in the vibration characteristics of suspended cables with different sag-to-span ratios.And due to the existence of the initial tension,the effects of the same degree of heating and cooling conditions on the structural vibration characteristics are different;(3)The effect of temperature changes on the vibration characteristics of suspended cables under multi-frequency excitation was studied.Dimensionless parameters are introduced to take into account the effects of temperature changes,and the equations of motion of the suspended cable under twofrequency excitations in thermal environments are established.The multi-scale method is used to solve the amplitude-frequency response equations for various types of joint resonances of the suspended cable,and the stability of the steadystate solution are obtained.Through the amplitude-frequency response curve,time history curve and Poincaré sections,the influence of temperature change on the nonlinear vibration characteristics of the suspended cable under multifrequency excitation is analyzed.Research shows that the vibration characteristics of suspended cables will become more complicated under multifrequency excitation.Both the branch curve of amplitude-frequency response curves and the number of steady-state solutions have increased.Comparing the calculation results of the multi-scale method with the Runge-Kutta method,it is found that there is a good agreement between the multiple scales method and the Runge-Kutta method.