Dynamic Response Analysis Of Bridge Under Moving Load

Transportation is the skeleton supporting regional economic development,and bridges are the joints to maintain smooth traffic.The health of bridge structure is related to the normal operation of transportation system.At present,many bridges in service in our country have more or less potential safety problems.In order to ensure the safe operation of structures and avoid accidents,it is necessary to evaluate their health status.Therefore,finding an effective bridge damage assessment method has become a hot issue in this field..In many studies,structural damage identification based on dynamic testing is receiving widespread attention.In this paper,the frequency parameters are selected to identify the damage of bridges,and the effect of mobile vehicles is introduced.The change of bridge frequency under the action of mobile vehicles is used to construct damage location parameters to identify the damage.Finally,the identification effect of this method is verified by the analysis of real bridges.The main research contents are as follows:1.This paper systematically summarizes the research status of structural damage identification based on vibration at home and abroad,focuses on the dynamic fingerprint method,classifies several commonly used damage identification methods,and analyses their advantages and disadvantages.2.The mechanism of frequency used in damage identification is elaborated.The possibility of using four frequency fingerprints for damage location is theoretically analyzed,including frequency change ratio,frequency change square ratio,frequency change ratio and regularized frequency change rate.3.Taking a simply supported hollow plate as an example,the validity of fourfrequency fingerprints was compared by finite element simulation,and the stability of two frequency fingerprints was studied.It was considered that the ratio of frequency change rate and regularized frequency change rate fingerprints were better for damage location.Finally,the single damage of the hollow plate was identified by these two fingerprints.4.In view of the limitation of frequency fingerprint method in identifying bridge damage,the author regards mobile vehicles and bridges in dynamic testing as a system and Vehicle-Bridge frequency as a physical quantity of bridge damage identification.Vehicle is simplified as a moving spring-mass model.The frequency variation law caused by vehicle action at different positions of bridge is analyzed.Damage location parameters are constructed by using the model.Damage location is judged by abrupt change of parameter curve.Damage identification of a three-span continuous beam bridge under different working conditions is verified by numerical simulation.