Study On The Structure State Of Freight Railway Bridge Based On Real-time Monitoring Information

The freight railway bridge has a single load and a large live load.Under train loading,the bridge is prone to structural damage.At the same time,the environment of the bridge site will have an impact on the structural state of the bridge.This article will evaluate the operation status of the main girders of freight railway bridges based on monitoring information.The main research contents include:(1)According to the distinctive features of freight railway bridges,according to the domestic design and verification specifications of railway bridges,the key monitoring data is determined by the vertical and horizontal displacements of the main girder,the frequency of the main girder's transverse and vertical directions,the longitudinal strain of the main girder,and the vertical angle of the beam end.Combined with the characteristics of railway bridges,and referring to the dynamic load test methods in bridge load tests,relying on the actual conditions of the project,the ratio of measured values to theoretical values is determined as the key evaluation index of railway bridges;the threshold value is used as the limit of damage state,and the bridge is established.The initial state is based on the state of health,and the target range is defined.Based on the characteristics of each indicator,the corresponding score formula for the score is determined.The score range is 0-100.Refer to the bridge assessment procedure and the score is divided into five indicator states to assess the grade.(2)For the comprehensive evaluation of railway bridges,the AHP and variable weight assessment theory are applied to construct the evaluation model of the main beam operation status.The subjective weights of the experts are determined by using the uncertainty judgment matrix and the consistency check,and the objective weights of experts are determined by using the opinion concentration and authority.At the same time,it assigns comprehensive variable-weight assessment methods to grasp the principle of balance.Finally all determine the weight of each index in the evaluation model,and establishe a complete structural evaluation system.(3)An ANSYS simulation model of a 32 m simple beam is established.After the finite element model is modified,the structural integrity,damage,damage,10%,20%,30%,40%,and 50% damage are established respectively by changing the elastic modulus.Different load conditions,random temperature and random wind load are added in the model.After simulation analysis,Matlab calculation program is writed to process data.The score results decreased with the intensification of the damage status,and the correlation with the size of the vehicle load was not significant.The results show that the proposed railway bridge assessment model has good applicability.(4)Relying on the Shui Ya Zi Dun railway bridge in Qinghai Province,for its large bridge length and many bridge spans,the environment is complex.A health monitoring system is established by the main beam's vertical,horizontal acceleration,main beam longitudinal strain,pier top strain,temperature,wind and humidity,and conducted onsite deployment.At the same time,according to the assessment model of the bridge structure proposed in this paper,there are targeted evaluation indicators,re-empowerment,and engineering verification analysis.The results show that the condition of Shui Ya Zi Dun Railway Bridge is assessed as Grade 1,and the operation status is good.