Research On Construction Process Analysis And Control Technology Of Long Span Steel Truss And Flexible Arch Bridge

Steel truss flexible arch bridge is a kind of bridge structure with large span capacity and strong structural stiffness.It overcomes the shortcoming of insufficient stiffness of long-span bridge and has been paid attention by the engineering circle.However,there are few researches on the construction control method of steel truss flexible arch bridge.Taking the construction of the world’s largest span railway continuous steel truss flexible arch bridge as the engineering background,this paper studies the construction control technology of steel truss cantilever assembly,the closure construction control technology of steel truss beam,and the horizontal assembly and lifting control technology of flexible arch.The main work is as follows.(1)The stress analysis of cantilever assembly of steel truss is carried out,the stress-free line and the stress free length of the members are calculated.During the construction process,the finite element model is modified by parameter identification and the assembly line of each construction stage is calculated to control the cantilever assembly line.The measured and calculated data are compared and analyzed,and the monitoring data show that the linear and internal force errors in the construction process meet the control requirements.(2)This paper studies the influence factors of the geometric position of the closure of steel truss girder,including the adjustment measures of the jacking beam,the ambient temperature and the temporary construction load.The formulas for calculating the displacement value of each fulcrum and the elevation of closure opening are derived and applied in closure construction.The influence of temporary construction load on the closure of the top falling beam is studied,and the adjustment measures are determined according to the hoisting scheme of the closure.The closure monitoring data show that the closure construction error meets the control requirements.(3)The influence of the deformation of steel truss beam on the horizontal alignment of flexible arch is studied.The deformation of steel truss beam is calculated,and the parameters of the finite element model are modified according to the measured data in the horizontal alignment construction.Finally,the comparison error between the deformation of steel truss beam and the finite element calculation results meets the control requirements.The calculation method of pre lift value of support is studied and applied in engineering.The error analysis of the arch rib splicing shows that the splicing angle error has the greatest impact on the arch rib alignment.A "two-point control method" is proposed to improve the accuracy of the splicing angle.The target value of alignment correction in the horizontal splicing process is calculated to ensure the control accuracy of the arch rib horizontal splicing alignment.Finally,the retest alignment meets the control requirements after the completion of the flexible arch horizontal splicing.The internal force,alignment and stability of the flexible arch lifting scheme are analyzed,and the reasonable construction suggestions and alignment control scheme are put forward.The research results of this paper have been verified by practical projects,which can provide reference for similar projects.