Nonlinear Dynamic Analysis And Vibration Control Research Of Vehicle-flexible Cableway Bridge

Cableway bridges have been widely used in bridge projects such as scenic spot,temporary engineering and military traffic.The vibration problem of the cableway bridge under the load of vehicles has attracted attention.The vehicle-cableway bridge system is essentially a time-dependent dynamic system.Under the action of moving vehicle loads,the cableway bridge itself will exhibit strong geometric nonlinearity.Therefore,the vehicle-flexible cableway bridge system not only has the properties of time-dependent,but also strong geometric nonlinearity.However,there are few studies on the coupling vibration of vehicle-cableway bridges.Based on an actual highway cableway bridge,research on nonlinear dynamic analysis and vibration control of vehicle-flexible cableway bridge are carries out in this paper.The main research work is as follows:1)A nonlinear finite element method for vibration analysis of vehicle-flexible cableway bridge system is proposed.Based on updated Lagrangian formulation and the principle of virtual work,taking the cableway bridge and vehicle as a whole dynamic system,the nonlinear incremental motion equation of the vehicle-flexible cableway bridge system is established.In the incremental motion equation,the characteristic matrices of the vehicle subsystem,the cableway bridge subsystem and the vehicle-bridge interaction subsystem are derived in detail.Because the vehicle-flexible cableway bridge dynamic system is quite different from the traditional nonlinear structure,the nonlinear characteristics of the system are analyzed in detail.Based on this particularity,an iterative algorithm for solving the dynamic response of time-dependent nonlinear systems and a general calculation program for dynamic analysis of vehicle-flexible cableway bridge system are proposed in this paper based on Wilson-? method and Newton-Raphson iterative method.The applicability of the method is verified by three typical examples,and the effect of nonlinearity on vehicle-flexible cableway bridge time-dependent system is analyzed.2)A vibration control method for vehicle-flexible cableway bridge system based on eddy current tuned mass damper is proposed.Two devices to suppress the vibration of bridge are proposed.According to the mode shape and natural frequency of thecableway bridge itself,set the parameters and arrangement scheme of the eddy current tuned mass damper,and the corresponding eddy current damping force is also calculated.On this basis,the nonlinear incremental motion equation and numerical analysis model of the vehicle-flexible cableway bridge-eddy current tuned mass damper system are established.Two numerical examples are used to verify the damping effectiveness of the eddy current tuned mass damper.Through the optimization analysis of various parameters,the optimization strategy of the vibration suppression device for the vehicle-flexible cableway bridge nonlinear system is obtained.3)An analysis method for assessing the cableway bridge based on the baseline numerical model is presented.The initial numerical model of the vehicle-flexible cableway bridge system is established according to the design parameters of a real cableway bridge,and the initial numerical model is updated by static load test and ambient vibration test data.After obtaining the baseline numerical model,it is further verified by using the dynamic test data.Finally,the bridge assessments,including a heavy truck and a traffic flow that passing through the bridge,are respectively carried out by using the baseline FE model.The nonlinear FE assessment methods and evaluation results present in this paper can provide a reference for analysis the similar flexible structure.