Research On Construction Control Of Superstructure Of Long Span Concrete-filled Steel Tube Arch Bridge

With the wide application of long-span concrete-filled steel tube arch bridges in China's high-speed railways,the research on simulation analysis and monitoring technology of theirs forming process has been paid more and more attention.The thesis takes a concrete-filled steel tube arch bridge under construction as the engineering background,and uses finite element analysis software to model.The safety of the temporary structure during the erection of the arch ribs was checked,and the results showed that the strength,stiffness and stability of the temporary structure met the requirements.The deformation,stress and stability of the bridge superstructure during the construction process are calculated,and the results show that the structure deformation is reasonable,the force is safe,and the stability is good during the construction process.The natural vibration characteristics of the bridge in the completed state are calculated and analyzed,the influence of the construction sequence on the deformation of the arch rib and the internal force of the suspender is discussed,the influence of the form and number of cross braces on the structural stability is analyzed,and the bridge operation stage The deformation,stress and steady state of the structure were checked.The results show that the lateral bending rigidity of the arch rib is small,and the lateral rigidity of the arch rib should be strengthened in the seismic design of the bridge,the sequence of constructing in the order of first pouring the concrete and then removing the support and tensioning the suspender along the arch foot to the vault is more beneficial to the project construction,the form and number of cross braces have a greater impact on the stability of the structure,which verifies the rationality of the number and form design of the bridge cross braces,the bridge is safe in operation and service.In addition,the stability state of the structure during the concrete pouring is simulated and analyzed,the results show that the stability meets the requirements during the concrete pouring.The effects of parameters such as superstructure stiffness,bulk density,inclination angle of arch ribs,in-tube concrete compactness and temperature on the deformation of the arch ribs,internal forces of steel tubes,internal forces of hangers and structural stability are analyzed.The results show that steel tube stiffness,temperature and concrete bulk density in the tube are the main parameters that affect the deformation of the arch rib,temperature and arch rib inclination are the main parameters that affect the steel tube stress and axial force,the steel tube stiffness,temperature and arch rib inclination are the main parameters that affect the steel tube bending moment,the stiffness of the suspender,the inclination angle of the arch rib,the bulk density of the concrete inside the pipe,and the temperature are the main parameters that affect the internal force of the suspender,the stiffness of the steel pipe,the transverse brace,the concrete void in the pipe,the inclination angle of the arch rib and the bulk density of the concrete inside the pipe are the main parameters that affect the stability of the structure.Finally,the structural analysis model was revised according to the construction plan of the arch rib frame,the construction pre-camber of the arch rib was calculated,and the bridge superstructure construction monitoring plan was compiled,some deformation and stress data monitored on site in the early stage were processed and compared with theoretical calculation values.The results show that the linear monitoring data of brackets,beam deformation and arch rib erecting mold elevation have small errors from theoretical calculations,and the linear control is good,and the surface-mounted strain gauges can be added to the stress monitoring points for parallel measurement and selection of temperature changes,and the measures such as on-site testing are carried out in a stable period to improve the accuracy of stress monitoring data.