The Bridge Technology Research Of The Freight Railroad Bridge Based On The Dynamic Response

There are large live loads on the railway bridge,this cyclic load of the train will make the bridge appear structural fatigue.The erosion of the bridge site environment will cause the structure to produce different degrees of disease and make the structure state abnormal,that will affect normal use.What's more,if the abnormal information cannot get attention,it is possible that there are catastrophic accidents in extreme conditions.Therefore,in order to study the state of the bridge structure under the influence of the environment and the cyclic load of the train,this paper focuses on the bridge state assessment for the purpose of research work.The main research contents include:(1)Aiming at the characteristics of single structure,multi-span,large live load and obvious structural dynamic response of Shui Ya Zi Dun Bridge,the optimal arrangement method of the acceleration sensor based on the analytic hierarchy process(AHP)is proposed.This method analyses the influence of the four attributes on the two aspects of the structure vibration response and investment cost(like the position of the track joint,the bridge line,the pier height,the distance from the 0 # abutment),formed from the plan layer,criterion layer to the layout optimization model of the acceleration sensor three level target layer on the arrangement of the sensor.Based on the influence,the optimization of the acceleration sensor of the 130 overwater Shui Ya Zi Dun Bridge is completed.(2)The control range of the key characteristics of different railway bridge codes is analyzed.Taking the lateral frequency of the main girder,the vertical frequency of the main girder,the lateral transverse amplitude,the transverse acceleration of the main girder and the vertical acceleration of the vibration as the key characteristic index as the key characteristic indexes,the key characteristic indexes of different railway bridge codes are constructed.(3)Analyze the control range of the key indicators of the main beam structure of different railway bridges specification,and propose the evaluation model of the railway bridge structure state which integrates the multi-level threshold interval and the statistical distribution index of the monitoring information.The finite element simulation is used to analyze 32 m T-beam and the key characteristics of the structure under the damage degree of 0%,10%,20%,30% and 50%,and the operation performance of the main beam structure under each condition is evaluated.In the condition of good condition and damage 10%,the evaluation level of the main girder is Grade 1(A1B1);20% damage and 30% damage,the evaluation level of the main girder is Grade 3;when the damage is 50% damage,it is Grade 5.The results show that the proposed model of railway bridge state assessment has great applicability and strong sensitivity to structural change.(4)Based on the large-scale railway bridge of Shui Ya Zi Dun in Qinghai Province,aiming at its long length and multi-span,health monitoring system includes the main structure of the beam vibration acceleration,vertical vibration acceleration,the main beam strain,the bottom of the head strain,the main beam structure temperature and other environmental parameters is established and site installation deployed.At the same time,the engineering verification and analysis of the railway bridge structure state is carried out by using the fusion multi-level threshold interval and the statistical distribution index of monitoring information.The results show that the evaluation status of the bridge is very good(A1B1),and its operation performance is very good.