Rapid Bridge Test And Damage Identification Based On Moving Impact

With the increasing prosperity of bridge construction,the number of bridges in service is increasing,and the problem of bridge health maintenance is becoming more and more serious.Bridge maintenance is the responsibility of the bridge inspection units,but the existing bridge detection methods mainly rely on manual detection,which is difficult to cover all the bridges in service.Moreover,for small and medium span girder bridges with large quantity,the work cycle of a single bridge detection project is long,and the time interval of the same bridge detection is long,therefore it is difficult to grasp the health status of the bridge structure in real time.In order to solve the problem,a method of rapid bridge test and damage identification based on vehicle moving impact force is proposed.This method makes full use of the convenience of vehicle,the excitation characteristics of impact load and the dominant idea of "input-output",which can quickly detect the bridge and preliminarily determine the overall damage degree and bearing capacity of the bridge.The main research contents of the thesis are as follows:(1)This thesis innovatively proposes a calculation method of dynamic vertical wheel force,which transfers the installation position of measuring wheel force sensor from the complicated wheels to the transmission path of wheel force which has a simple structure.The method makes use of the characteristics of the force sensor and the structure of the vehicle body to obtain the real wheel force,the calculated wheel force can be used as the input excitation force of the vehicle moving impact vibration modal test.In this thesis,the rationality of the calculation method was verified by the experiment test,which laid a solid foundation for the later rapid impact vibration test of the bridge,and was a favorable guarantee for the idea of "The vehicle is moving at the same time with measuring wheel force and impacting bridge".(2)In this thesis,a rapid test was carried out for the actual bridge,by means of hammer and vehicle moving impact vibration modal test,the flexibility matrix of the bridge structure was calculated.The two methods prove the correctness,applicability and engineering value of the bridge rapid test method respectively.The correctness of the modal information calculated by the bridge rapid test was verified by comparing with the modal information calculated by the traditional impact vibration test of force hammer.(3)Aiming at the actual bridge which required static load experiments,this thesis conducted vehicle moving impact vibration modal test and the impact vibration modal test of force hammer installed on the vehicle,and measured and calculated the flexibility matrix of the bridge structure.The purpose of latter test is to fully develop the bridge rapid detection method of moving vehicle.By comparing with the structure information actually measured by the bridge detection unit,the correctness of the structure modal information calculated by the bridge rapid test is verified.(4)In this thesis,a rapid preliminary assessment method for the bearing capacity of the bridge is presented,which is also an assessment method for the overall damage degree of the bridge.It makes full use of the deflection predicted by bridge rapid modal test,and the method is integrated into the domestic bridge bearing capacity assessment method.This method can be used before the static load experiment of the bridge,then the bearing capacity of the bridge structure and whether the static load experiment is needed can be determined in advance,which can save manpower and material resources needed in some bridge load experiment.