Research On Key Construction Technology Of 128m Nielsen System Simple Supported Arch Bridge

In recent years,concrete-filled steel tube tied arch bridges have played an increasingly important role in the construction of bridges across the country due to their prominent characteristics such as high strength,good integrity,beautiful appearance,light weight,and short construction cycle;With the increasing span of arch bridges,people have gradually paid more attention to the problems of construction monitoring;This article uses a 128 m Nielsen system tied arch bridge on a high-speed railway across a highway as the background.The bridge adopts the method of lifting the main beam and then arch ribs.The paper analyzes and monitors the entire construction of the bridge superstructure.The main research contents are as follows:(1)The paper briefly introduces the structural form of concrete-filled steel tube tied arch bridge and the monitoring method during construction,and expounds the development and research status of construction monitoring of tied arch bridge;(2)The paper according to the structural characteristics of the bridge,the finite element calculation model of the bridge was established using Midas/Civil,and the entire construction process of the bridge was simulated;The paper analyzes the changes in the structural forces and displacements of the bridge’s tie beams and arch ribs during the entire construction of the bridge and the changes in the suspension bridge cable force during the construction;The paper summarize the stress and deformation trends of the structure of the bridge at all major construction stages,and obtain the laws of structural force and linear changes of the tie beams and arch ribs and the change of cable forces of the suspension rods;The paper calculations proves that: During the entire construction phase and the final stage of the bridge construction,the structural stresses of all parts of the bridge met the requirements of the code,the displacement changes did not appear to exceed the limit,and the cable force values of the boom are all within the range required by the code;(3)The paper draw up a construction monitoring plan for the bridge’s beams andarch ribs to guide the construction monitoring of the bridge’s superstructure,and monitor the bridge’s beams and arch ribs according to the developed monitoring plan;By monitoring the stress values of the tie beams and arch ribs at each construction stage,the structure can be reasonably stressed and the construction safety can be guaranteed during the construction of the bridge;The paper analyze the deformation monitoring data of the tie beams and arch ribs,and grasp the deformation of the bridge superstructure in real time.By comparing the calculated and measured values,ensure that the deformation of the bridge superstructure meets the requirements of the code;The boom tensioning scheme of the bridge was developed to draw the 56 suspension beams of the bridge in two times.After the first tensioning was completed,the finite element calculation parameters were modified based on the field measured boom data to make the theoretical calculation parameters and The actual situation at the scene coincides;Finally,the paper comparing the measured results with the theoretical calculation results,we can see that: The linear change rule of the bridge is consistent with the calculated value,and the linear change is within the requirements of the code;The difference between the measured value of the bridge’s stress and the theoretical value is not large,which proves that the bridge structure is in a safe state during construction;The error between the measured value and the calculated value of the suspension cable force did not exceed the limit,and the indicators met the requirements of the specification,which can be used as a reference for construction monitoring of similar long-span tied arch bridges.