Research On Suspender Replacement Technology Of Concrete-filled Steel Tube Arch Bridge

Due to the early construction of some half through concrete-filled steel tubular arch bridges,the suspenders of many arch bridges have already reached their service life and have to be replaced.Based on the project of Jiangshan Chengzhong bridge in Zhejiang Province,this thesis uses Midas civil to analyze the stress of the suspender of the arch bridge and optimize the replacement of the suspender.The main research contents and conclusions are as follows:(1)The finite element model of steel longitudinal beam reinforcement of Chengzhong bridge is established by using Midas civil.Through analysis,it is found that the adoption of steel longitudinal beam reinforcement measures has significantly enhanced the integrity of the bridge structure,more uniform stress distribution in the arch rib,greatly improved the safety of the suspender of the arch bridge,and can ensure the ability of the corresponding suspender on the cross beam not to fall off the beam after the middle and side cables of the middle span and the side cables are broken.(2)The cable force of suspenders of Chengzhong Bridge is tested by frequency test method,and it is found that the measured cable force of suspenders is uneven.Midas Civil was used to simulate and analyze the replacement process of a single suspender in the construction process of temporary suspender method.Through the comparison between equal step tensioning and variable step tensioning,it was found that the two tensioning methods for temporary suspenders can restore the bridge to its original state,but the variable step tensioning method will make the cable force of suspenders and the bridge deck displacement increment smaller,making the replacement of suspenders more stable.ABAQUS is used to check the structural stress of the temporary beam when the suspender is replaced with the temporary lifting device.The maximum stress is within a reasonable range,indicating that the structural stress meets the safety requirements.During the construction of suspender replacement of Chengzhong Bridge,the bridge deck alignment meets the design and specification requirements,and the bridge structure is in a safe state.(3)In the process of cable force optimization during the replacement of suspenders,the cable force uniformity is taken as the objective function and the minimum square sum of arch rib bending moments is taken as the objective function to optimize the cable force of the suspenders of the whole bridge.Through comparison and analysis,the cable force uniformity is taken as the objective function to make the cable force of the whole bridge more uniform after optimization,Although the bending moment can be effectively reduced,it makes the force of the suspender of the whole bridge uneven,so it is more reasonable to optimize the cable force based on the uniformity of the suspender cable force as the objective function.