Research On Dynamic Coupling Modeling And Response Analysis Of Stay Cables And Magnetorheological Dampers

As a hub of marine economic transportation,cable-stayed bridge is carrying out a channel for the development of marine economy.The safety problem of bridges needs to be noticed.The cable-stayed cable is a stress component of the cross sea bridge.With the span of the span bridge becoming longer and longer,the vibration control problem is also increasingly prominent.In complex marine environment,how to effectively reduce the vibration of cables has become a research hotspot in the field of marine engineering.In this paper,in order to establish the dynamic coupling model of cable and MR dampers and improve the accuracy of response,the influence law and mechanism of the vibration characteristics of cable stayed cables under different boundary conditions are explored.The mechanical structure,mechanical performance test and dynamic modeling of MR dampers are carried out,and the inclined cable and M under the external load excitation are carried out at the same time.Study on the mechanism of dynamic coupling response of R damper.The specific research contents are as follows:First,a vibration model with elastic boundary constraints is constructed.The transverse vibration characteristics of the cable under the elastic boundary constraints are studied.The linear constraint spring and torsional constraint spring are introduced at both ends of the cable.By setting the corresponding stiffness coefficient to the spring,the lateral vibration model of the cable can be obtained under the elastic boundary condition.The vibration displacement is expanded by Chebyshev series,so that the lateral displacement is smooth enough in the whole solution domain.The lateral vibration of cables is analyzed under different boundary conditions.The results are in good agreement with the references,which verify the correctness of the constructed model.The influence of linear constraint spring stiffness and torsion spring stiffness on the lateral vibration characteristics of cable is analyzed.On this basis,the dynamic response mechanism of linear restrained spring and torsion spring to the dynamic response mechanism of the cable is investigated.The results show that the vibration frequency of the cable-stayed cable increases gradually in the boundary condition,which is 16.50%,16.03%,15.90%,14.05%.With the increase of the boundary constraint coefficient,the vibration frequency of the cable-stayed cable tends to be stable,and then the influence of the boundary constraint stiffness on the cable response is explored.Secondly,the mechanical characteristics of MR dampers are studied by experimental method.Using the MR damper designed independently as the research object,the dynamic performance test platform of MR damper is set up.The mechanical properties of the excitation current under the conditions of 0,0.2,0.4,0.6 and 0.8A are analyzed with the temperature of 20,40,60 and 80,and the change of the output damping force and the exciting current and the temperature are investigated.Law.The results show that the damping force increases with the increase of the exciting current,and the damping force decreases with the increase of temperature.When the temperature changes from 20 to 80,the damping force of the output damping force from 0.610 k N to 0.330 k N is 45.9%,and with the larger current,the attenuation trend of this change gradually decreases.Thirdly,a dynamic model of MR resistors under magnetic seal structure is established.The mechanical properties of the MR damper under the conditions of temperature of 25,0,0.2,0.4,0.6 and 0.8A are analyzed.The dynamic performance of the magnetic seal structure MR damper can not be expressed accurately by the Bouc-Wen model.On this basis,a dynamic model of the three stage seal is proposed,which is compared with the experimental data and the simulation results.The research shows that the proposed MR damper model can accurately reflect its displacement,velocity and damping force characteristics.At the same time,the excitation current is 0,0.2,0.4,0.6,0.8A,and the amplitude is 40 mm sinusoidal excitation,and the overall error is less than 1.8% through the test data compared with the simulation data.The correctness of the established model is further verified.Finally,a coupled model of stay cable and MR damper system was constructed.The principle of energy variation is used to construct the coupled model of stay cables and MR damper system.The vibration displacement function of the coupled system is constructed by the Chebyshev series method,and the vibration response of the coupled system under external load is solved by the Newmark method.Take the C20 cable-stayed bridge of Zhaobaoshan Bridge as an example,the displacement response of coupled system under free vibration and harmonic loads is studied.The results show that the MR damper significantly reduces the lateral vibration displacement amplitude of the cable.The larger the amplitude of the external excitation is,the more significant the reduction in the displacement of the cable in the coupling system can effectively control the vibration amplitude of the cable.When the external excitation When the frequency reaches 2 to 3 times of the vibration frequency of the coupled system,the system displacement response shows a periodic change.