Alignment Of Composite Beams Of Long-span Cable-stayed Bridges Study On The Influencing Factors Of Control

Cantilever assembly method is one of the most widely used construction methods for main girders of long-span composite girder cable-stayed bridges at present.The key problem of cantilever assembly construction lies in choosing suitable manufacturing and installation alignment,adjusting errors in construction process,and making the internal force and alignment of bridge structure meet the requirements of design theory.Based on the engineering background of Poyang Lake Second Bridge and Madas finite element analysis software,the full bridge model of Poyang Lake Second Bridge during construction stage is established.Under linear and non-linear conditions,the installation alignment,manufacturing angle,manufacturing dimension and manufacturing alignment of the main girder are compared and analyzed.The sensitivity analysis of manufacturing errors of key components to internal force and alignment of cable-stayed bridge in construction stage is studied.The problems in actual construction are solved by least square method and grey system theory.The propagation characteristics of manufacturing errors of key components in construction process are discussed.The main contents of this paper are summarized as follows:(1)The development and basic principles of construction control methods and control concepts of cable-stayed bridges are introduced.The treatment methods of parameter errors in construction control of cable-stayed bridges and their engineering applications are elaborated in detail.(2)Introduced the basic principle of the stress-free state quantity of the main girder,discussed the difference and internal relationship between the design alignment,installation alignment and manufacturing alignment,elaborated in detail the calculation method of the main girder installation and manufacturing alignment under zero initial displacement method and tangent initial displacement method,introduced the calculation principle of least square method of parameter identification and grey system theory.(3)Based on the zero initial displacement method,the installation alignment,manufacturing angle,manufacturing dimension and manufacturing alignment of the main girder of Poyang Lake Bridge under linear and non-linear conditions are calculated respectively.(4)The influence of manufacturing errors such as angle between beam segments,beam weight,length of beam segments,cable length and tower height on bridge completion stage is studied,and the practical application of least square method for parameter identification and grey system theory is calculated.(5)The influence of the angle between beams,the weight of beams,the length of beams and the manufacturing error of cable length on the alignment and its propagation characteristics during the construction stage are calculated and analyzed.The manufacturing errors of intersection angle,beam weight and cable length show typical convergence with the assembly of cantilever beam segments,while the influence of manufacturing errors of main beam length on subsequent beam segments will accumulate with the construction process,showing typical non-convergence characteristics.Through the work and research,the influencing factors of alignment control of composite beams of cable-stayed bridges have been more deeply understood,which can provide reference for the design and construction of similar projects in the future.