Research On The Hanging Basket Construction System Of The Wide Double-box Girder With Single-box

Although the existing cast-in-place box girder construction schemes have become more and more mature at home and abroad,due to the limited application of the wide-width double-box single-cell box girder structure in bridge projects,there are currently less mature theories and experiences available for reference.Improper use will have an adverse effect on the stress and the shape of the bridge structure.Based on the Shanxi Provincial Transportation Department project “Research on Key Techniques of beam arch composite bridge with Large Span,Wide Span”,based on the construction of the main bridge of Hanjiang Bridge in the east of Ankang City,this paper explores the hanging basket construction system with the wide-span double box single-box girde during the construction system.Firstly,by collecting the existing engineering data and design drawings,two construction techniques of bridge deck full-width non-synchronous construction and bridge deck full-width synchronous construction are proposed.Two kinds of construction processes are compared and analyzed in four aspects such as force,safety,economy and construction convenience.Using the combination of numerical analysis and theoretical analysis,the equivalent load distribution pattern of the bottom basket longitudinal beam in the single-battery hanging basket construction system was studied;Secondly,using the finite element software Midas/Civil to carry out a three-dimensional solid modeling of a single basket-mounted device,checking the strength,stiffness and stability of the construction hanging basket system under the pouring and running conditions;Finally,using the spatial finite element theory,taking into account the effects of structural elasticity,material and geometric nonlinearities,combined with large-scale general-purpose finite element software ANSYS,the elastic stability and ultimate bearing capacity of the main system of the basket were simulated and calculated.Using non-linear finite element method,the influencing factors of the ultimate bearing capacity of the main basket were analyzed from three aspects: nonlinear factors,initial defects and material strength.The research results show that the construction process of a single hanging basket with non-simultaneous construction of bridge decks is superior to the two deck hanging construction techniques in terms of structural force,economy,and construction convenience,while the stability is slightly inferior.However,it is in line with actual engineering and regulatory requirements;Comparing the two types of simplified load calculation models of the bottom basket of the basket,numerical analysis is concise and theoretical analysis is complicated,but the latter is more in line with the actual forced mode of the hanging basket.To sum up the above two simplified models,the load calculation model in this paper is to multiply the distribution load of the web side stringers by 1.2 on the basis of the former load distribution;Through the eigenvalue buckling analysis and static nonlinear analysis of the main truss of the hanging basket,the ultimate load and safety reserve capacity of the hanging basket can be predicted and the failure paths and failure mechanisms of the components of the main basket system can be predicted.Through the analysis of the influencing factors of the ultimate bearing capacity of the main system of the hanging basket,the material nonlinear factors and material strength are the key factors affecting the ultimate bearing capacity of the main basket.Through the analysis of the elastic stability and ultimate bearing capacity of the main frame of the hanging basket's analysis,the main load-bearing structure and the force transmission member of the hanging basket's elasticity analysis,the weak parts of the hanging basket system can be found and then improved.