Under The Vehicle Vibration Modal Analysis Of Cable-stayed Bridge And Bridge Evaluation

With the improvement of China's comprehensive national strength and the introduction of a strategy along the way,no doubt to promote the further development of transport.Cable bridge as a key traffic engineering hub,after the completion of the maintenance and operation of more and more important.In order to monitor the service status of the bridge,it is necessary to build a health monitoring system,but for the health monitoring system of the cable-stayed bridge,there are many types of environmental incentive types,complex structure,non-linearity and wide measurement noise,data redundancy and so on.Facing the limitation of modal analysis technique,the modal parameter is difficult to solve and the error is large.Is to abandon the traditional mode of operation analysis,the use of highly controllable vehicle incentives,for modal analysis.For cable-stayed bridge monitoring signal and noise,the characteristics of big redundancy,by means of wavelet threshold de-noising for information processing,through power spectrum analysis,to determine the optimal threshold value function and the processing method.Then the experience extreme symmetry mode decomposition method is adopted to post threshold signal mode decomposition,gets some decomposition mode,on the basis of using the method of time domain amplitude,the time domain amplitude parameter,analyzes the damage to the influence of structural response in time domain amplitude parameters.In view of the randomness of vehicle operation,the lack of understanding of bridge frequency response function and the difficulty of modal analysis.In this paper,the three-axle heavy-duty vehicle model is optimized from the perspective of mechanics,and the numerical model of axle-bridge coupling is established.Then the theoretical solution of the single point excitation vibration equation is obtained,and the vibration response law of the bridge is studied by numerical analysis and theoretical analysis,and the most realistic vehicle excitation method is found.For the cable-stayed bridge to monitor the signal high noise,the characteristics of large redundancy.Through the wavelet threshold,the information is denoised,and the optimal threshold function and processing method are determined by power spectrum analysis.Then the empirical pole-symmetric modal decomposition method is used to decompose the signal after the threshold,and some decomposition modes are obtained.On the basis of this,the time domain amplitude parameter is used to obtain the time domain amplitude parameter,and the influence of damage structure response on time domain amplitude parameter is analyzed.For the large structure of cable-stayed bridge,the influence of material nonlinearity and geometric nonlinearity on modal analysis results can not be neglected.A method of simulating a cable-stayed bridge with composite entities,films and beam elements is studied,in which dampers,stoppers and prestressors are considered.In the study,the modal substructure technique is used to calculate the subordinate structure of the bridge in batches to solve the problem of insufficient computer computing ability.In the analysis,the initial state method is used to solve the geometric nonlinear problem by considering the small deformation assumption and the large deformation assumption.The constitutive model of concrete damage and the ideal elastic-plastic constitutive model are used to solve the non-linear problem of material.And the correctness of the finite element model is verified by static analysis.The method of wavelet threshold is used to denoise the vibration wave,and the modal parameters of the bridge are analyzed by means of ESMD method.On the basis of Elman network,a hierarchical neural network is constructed,and its validity and accuracy are verified by Fucai 3D data.On this basis,the damage of the bridge was evaluated,and good results were obtained.