Research On Control Technology Of Continuous Beam In Rotating Construction Based On Online Monitoring

Bridge swivel construction refers to a construction method in which the main girder of the bridge is made(poured or spliced)at the non-design axis position,and then the main girder is put in place by swivel traction equipment,and then closed.With the development of transportation,more and more bridges need to be built across existing lines.The application of bridge swivel construction technology is particularly important,which can not only ensure the normal operation of existing lines,but also ensure the safety of bridge construction.In this thesis,the newly-built Bei jing-Xiong an Intercity Railway crosses the continuous beam of Tianjin Main Canal of South-to-North Water Transfer Project,and the online monitoring system monitors the stress,deflection,angle,temperature,wind speed and other related data in the process of bridge rotation in real time,so as to master the data of construction process status and provide guarantee for the safe and smooth construction.By using the finite element software Midas/Civil,the stress state of the bridge structure in the process of turning is analyzed.Using BIM related software combined with on-line monitoring system,the bridge swivel construction process is simulated in 4D,so as to achieve the goal of dynamically displaying the construction process and improving the control effect.The main research contents and achievements of this paper are as follows:(1)In this thesis the key technology of continuous beam bridge swivel construction is introduced,especially explains the construction principle and steps,and carries out detailed design and experimental research on the weighing and counterweight before swivel.(2)The main p rinciple of bridge construction monitoring is introduced,the contents and methods of construction control are explained,and the monitoring results are analyzed based on actual projects,and the stress of measuring points,deflection of beam body,rotation angle,wind speed on site and environmental temperature changes in the process of turning are obtained.The monitoring results show that the stress difference between the measuring points of the beam section on both sides of the center symmetry position of the bearing is not more than 0.2MPa,which verifies that the weighing weight of the beam body is reasonable.In the process of turning,the center of the beam support and its adjacent section are always in a compressed state,and the stress changes little.The deflection difference between the two ends of the beam body is not more than 0.1mm,and the monitoring data changes little during the turning process,and the turning process is stable.In the process of swivel construction,the swivel is close to uniform speed.The maximum wind speed is 1.1m/s,and the difference of ambient temperature is within 10℃.The influence of wind speed and ambient temperature on bridge swivel construction can be neglected.(3)The finite element model of the bridge structure is established by using the software Midas/Civil,and the state of the continuous beam bridge before turning is simulated and analyzed,and the deflection of the main beam and the stress of the typical section are obtained.The early warning value is calculated by using the theoretical value calculated by the finite element model simulation analysis,and compared with the real-time monitoring data,which verifies the feasibility of the theoretical value in the turning process.It can be seen that the measured results remain within the first-class early warning range,and the theoretical value calculated by the finite element can be used as the reference value in the turning process of the bridge.(4)The BIM model of the swivel beam is established,and the continuous beam structure is parameterized by Revit and Navisworks to simplify the modeling steps.Combined with the theoretical calculation of rotating speed and the monitoring results of online monitoring system,the bridge swivel process is simulated and tracked in real time,and the bridge swivel construction is predicted and analyzed,so as to control the bridge swivel process and ensure its smooth progress.