Research On Evolution Law Of Structural Strength And Stiffness Of Split Movable Scaffolding System During Casting And Launching

Compared with traditional construction schemes,movable scaffolding system has been widely used in modern bridge construction due to its simple construction operation,high degree of automation management,and good bridge quality.A new type of movable scaffolding system used for pouring the upper box girder of a highway railway bridge is studied in this paper.The movable scaffolding system consists of two groups of four girders,arranged on the upper pier and the lower railway concrete girder.The movable scaffolding system used in traditional bridge construction is generally an overhead or underlane movable scaffolding system with a single or double girder.The design and use of a split movable scaffolding system with two sets of girder is still the first example.Based on the background of the Yangtze River Highway and Railway Bridge Approach Project of the CMSG-2 Bid Section of the newly-built Chaohu Ma’anshan Inter-city rail in Anhui Province,the structural characteristics and construction principles of the split movable scaffolding system is introduced.According to the construction conditions of the split movable scaffolding system,the structural strength,stiffness and stability are analyzed,and the coupling effect of the deformation of the concrete beam of the lower layer railway and the height difference of the column support on the bearing state of the movable scaffolding system is studied.The main research content is as follows:(1)The main research object is a new type of split type movable scaffolding system bridge building machine with collaborative upper and lower girder.It is a newly designed and firstly used new movable scaffolding system structure.This article provides a detailed introduction to the structural composition and working principle of the movable scaffolding system.(2)In order to ensure the construction safety of the movable scaffolding system structure,a comprehensive finite element model of the split type movable scaffolding system was established using the large-scale finite element analysis software ANSYS.Structural strength,stiffness,and first-order buckling stability analysis were conducted on the main load-bearing components of the movable scaffolding system under concrete pouring conditions;Conducted stability analysis of the beam structure under pouring conditions;The stability analysis of the nose bridge structure under through-hole conditions was conducted.(3)As the legs of the main beam of the mobile formwork are supported on the completed railway concrete beam of the lower level,the lower level railway concrete beam is a prestressed concrete box girder,which has a pre-arch value of about 30 mm,which has a camber value of about 30 mm.During the construction process of the movable scaffolding system,it will have a coupling effect with the upper movable scaffolding system system,affecting the bearing state of the girder of the upper movable scaffolding system.In this paper,the finite element model of railway concrete beam including prestressed system was established,and the coupling effect of the deformation of the lower railway concrete beam on the bearing state of the upper movable scaffolding system structure was simulated and analyzed by using the Iterative method.And the relevant calculation results were compared with the actual preloading data.(4)A simulation analysis was conducted on the descending process of the movable scaffolding system girder lifting system.In response to the problem of four point support height difference caused by the uneven surface of the lower railway concrete beam bridge,a structural strength analysis was conducted on the lifting system,and the allowable height difference range was obtained through theoretical analysis.