Mechanical Analysis Of Full-support Structure Used In Long-span Reinforced Concrete Bridge Construction

The Bailey beam and steel tubular scaffolding are commonly applied to the bottom support structures in concrete bridge construction.During construction,the support structure bears various construction loads such as the weight of main bridge,so the mechanical properties of the support structure are of great significance to the construction quality and construction safety of the bridge.Based on a tied-arch bridge project of reinforced concrete,the support structure system of through formwork construction of the concrete bridge is studied.The layout scheme of support structure is given.Using the Midas Civil finite element software,the structure models of hinge joint and semi-rigid junction are established and analyzed,respectively.The mechanical properties of the support structures under construction loads are discussed.The main research work in this thesis is as follows.(1)According to the construction conditions and construction scheme of reinforced concrete tied-arch bridge,combined with the "Technical code for safety of cuplock steel tubular scaffolding in construction",the layout scheme of scaffold and Bailey beam-steel pipe combined template support for through construction support in this project is proposed.(2)The cross section of the main girder of the concrete bridge changes along the axis,from the rectangular solid cross section at both ends to the single-box doublechamber cross section in the middle of the span.The effect of self-weight load of main girder structure on construction support is complex.The weight of the main bridge is calculated according to the structural form of the cross section of the bridge in different regions,and the linear distribution load acting on the I-beam at the top of the bracket is equivalently converted by the static equilibrium method.(3)The simulation modes of diagonal bracing in the support model and the relationship between the vertical and horizontal diagonal bracing bars and the stability of the support structure are discussed,which provides reference for the finite element calculation and actual construction of the full hall bracket.According to the calculation results,the calculation models of hinge joint and semi-rigid junction of the connection of vertical and horizontal bars of the support is established and analyzed by the Midas Civil finite element software.The influence of hinge joint and semi-rigid joint of vertical and horizontal bars connection on the bracket is discussed.The problems existing in the composite bracket with the Bailey beam and full hall bracket are analyzed and optimized.(4)The linear elastic stability analyses of the two numerical models with the hinged and semi-rigid connections are carried out,respectively.Then the eigenvalues and buckling modes of the support structures are obtained.By comparing the results of the two models,the influence of the simplification method of joint mechanical model on the stability of support structure is discussed.In the thesis,the FEM analytical results of the support structure system used in a reinforced concrete bridge construction not only provide safety security for this concrete bridge construction,but also provide reference for the design and actual construction of similar construction support.