Research On Key Technology Of Semi-rigid Suspender Replacement Of Arch Bridge

As the main load-bearing component of tied arch bridges,the accurate acquisition of cable force of suspension rods is of great engineering significance in both bridge construction and operation stages.In order to accurately obtain the force value of the suspension rod,the frequency method is often used.However,due to the unique structure of the concrete wrapped suspension cable,semi-rigid suspension rods are difficult to directly obtain the frequency value of the internal suspension cable that exerts the main tensile force,which poses difficulties in obtaining the cable force value and controlling the replacement of the suspension rod.This article studies the replacement of semi-rigid suspension rods and the method of obtaining the frequency of their internal suspension cables.Taking the Huangyuan Bridge suspension rod replacement project as the research background,a suspension rod replacement method based on the control of suspension rod force value is proposed.A suitable frequency and cable force calculation formula is established for the semi-rigid suspension rods of Huangyuan Bridge.The main research content and conclusions obtained are as follows:(1)A suspension rod replacement control method based on state equivalence method was proposed,and the mechanical principle of this method was explained.The actual engineering application effect of state equivalence method was verified with background engineering.(2)A study was conducted on the control standard for non cracking of bridge deck during replacement construction.Based on Midas finite element software analysis,a general control standard for suspension rod replacement was proposed using the non-destructive control condition of bridge deck pavement layer.The control standard was calculated using the influence matrix method and the control values were obtained.(3)A summary was made on the construction monitoring of the suspension rod replacement project,with a focus on the establishment of monitoring basis,monitoring objectives,detection content,and monitoring system.The engineering effect of replacing suspension rods using the state equivalent method was evaluated,and the elevation and cable force monitoring results proved that the replacement control effect of this method was good.(4)The vibration equations of string model and beam vibration model are summarized,and the transcendental equation of the two boundary conditions is simplified by Rayleigh method and the method of substituting dimensionless parameters.On this basis,the semi-rigid suspender model is established by using Abaqus software,and the relationship between semi-rigid suspender frequency and cable force is studied with the method of adding mass blocks,and the calculation formula of semi-rigid suspender force applicable to the project is obtained.