Evaluation Of Fracture Condition Of Continuous Girder Bridge Based On Vehicle-Bridge Coupled Vibration

During the process of the vehicle passing through the continuous beam bridge,the bridge continuously undergoes repeated actions of loading and unloading,and is prone to diseases such as fatigue damage,cracks,etc.,which may cause greater structural damage,which will directly affect the bridges.Service life.Therefore,the evaluation of the crack status of bridges is one of the research topics that the bridge engineering circles in the world are paying more attention to.Based on the theory of vehicle-bridge coupled vibration and wavelet transform theory,the paper evaluates the evaluation of cracks in continuous beam bridges.The main research work and achievements are as follows:1.After introducing the classical theory of vehicle-bridge coupled vibration,the large-scale numerical analysis software ANSYS was used to establish the two subsystems of the bridge and the vehicle using the command flow,and to form a coupling effect,and to compose the corresponding coupled vibration of the bridge and the road bridge.The calculation and analysis procedures were used to obtain and verify the bridge mid-span displacement,vertical body vibration displacement,and vertical vibration speed of the vehicle body.2.Focusing on the model of single axle vehicle(1/4 vehicle),the cracks of continuous beam bridges are analyzed.The mathematical analysis software MATLAB was used to acquire the wavelet analysis toolbox,and the fracture location and crack depth of the continuous beam bridge were effectively identified by the wavelet coefficient map,the wavelet coefficient gray map,and the wavelet coefficient modulus maximum track map of the continuous wavelettransform.And the number of cracks.Among them,the closer the fracture location is to the middle of the bridge,the easier it is to identify the fracture.When the fracture is located at the end of the bridge,it cannot be identified.With the increasing degree of fracture,the peak value of the wavelet coefficient mutation becomes larger,and the crack recognition effect is more obvious.The presence of cracks can also be observed in the modal maximum locus trace.When there are multiple crack damages in the continuous beam bridge,the cracks appear in the wavelet coefficient grayscale graphs as multiple bottom-up penetration bright seams in the wavelet coefficient diagram.In the performance of multiple mutation peaks.3.The influences of three important parameters of vehicle model,such as vehicle speed,vehicle weight,and vehicle spring stiffness damping,on the identification of cracks in continuous beam bridges are studied.Based on the analysis,the following conclusions are obtained: When the vehicle speed is less than the maximum,the identification of cracks is most beneficial;when the vehicle mass is large,the crack recognition effect is good;the impact of spring stiffness damping of the vehicle model is very small and can be ignored.4.When using a two-axle vehicle(1/2 vehicle)model to identify bridge cracks,the stage where the front and rear wheels of the vehicle are located on the bridge is the scope of study.The following conclusions can be drawn: All the displacement responses of the dual-axis vehicle model cannot effectively identify cracks.There is;in terms of speed,only the vertical speed of the axle mass point can roughly identify the presence of cracks.The assessment of cracks in continuous girder bridges studied in this paper can use vehicle response to identify bridge cracks,which greatly facilitates the engineering implementation process of bridge detection and assessment.It has certain application reference value and theoretical guidance significance for scientific research and engineering practice of bridge detection and monitoring.