Girder Bridge Damage Detection Based On Response Of Vehicle-bridge And Lifting Wavelet Transform

All kinds of cumulative damages will appear on the bridge along with the growth of its service life.If not be timely found,the damages often leads to serious consequences,which will directly endanger the stability of public transportation system and the safety of people's life and property.Therefore the regular damage monitoring and assessment of the existing bridge become crucial issues.However,the various traditional damage identification methods based on the dynamic test bears a variety of drawbacks,such as the dependence on the initial model and the experimental data,the blocking traffic by the detection process,the high cost of wide sensor layout and etc..Aiming at solving these problems,this paper establishes a multi-precision model of the moving vehicles,collects the axle acceleration response on the condition of vehicle loads,and makes use of the method based on lifting wavelet transform.The damages are identified,as well as the validity and practicability of the method is verified.The work of this paper mainly includes the following aspects:1.The paper summarizes the previous relevant research results in the practical and theoretical field of damage identification using bridge and vehicle response on the condition of moving vehicle load,and makes a classification of them.The basic principles and the effects of application examples of the various methods are also briefly discussed.2.The development history of wavelet analysis theory is analyzed,and the basic principle of the wavelet transform method and the basic process of lifting wavelet transform are described in detail.3.From the viewpoint of engineering application,the method of damage identification taking advantage of the acceleration response difference of bridge under different sizes of moving vehicle loads is proposed based on the previous wavelet transform method and theory and the lifting wavelet transform theory.Firstly,the acceleration response of bridge measurement points under different moving loads is collected.Secondly,the difference of response is addressed by lifting wavelet transform.Meanwhile,the effects of different damage degree,damage location,multiple damages,the position of the measuring point,driving speed and environmental noise on the damage identification effectiveness are discussed.4.A vehicle-bridge dynamic system is built considering the coupling effect.The vehicle is modeled as a single shaft spring mass damper consisted of bodywork,wheels,wheel spring damper and suspension spring damper.According to the numerical analysis method of vehicle-bridge coupling vibration,a vehicle-bridge coupled program based on Ansys and Matlab is written to calculate the acceleration response of bridge measuring point,body measuring point and axle measuring point.These data are deal by lifting wavelet transform to identify the damage location.In addition to the parameter analysis of factors such as damage degrees,the influence of the parameters on the damage identification is studied,which provides the basis for the design of the test vehicle.