Study On Construction Mechanics Behavior Of Stiff Skeleton Arch Bridge With Prefabricated Box Bottom Floor

CFST rigid frame arch bridge is widely used in the construction of bridges in our country because of its high bearing capacity and good spanning capacity.Generally,the construction process is assembling steel tube stiff skeleton arch,the concrete in the pipe is filled to form the steel tube concrete stiff skeleton arch,and then the stiff skeleton arch is used as the bracket to form a template for outsourcing concrete construction until the reinforced concrete arch ring is formed.This method has a long construction period,especially the construction of outsourcing concrete bottom floor is the most difficult.The bottom floor template needs to be erected in the air,and the construction safety risk is really high.Therefore,based on the first domestic stiff skeleton arch bridge with prefabricated bottom floor,Yutang Bridge,this thesis studies the mechanical behavior of the stiff skeleton arch bridge with prefabricated bottom floor.The research contents of this thesis are as follows:(1)It studies the calculation method of the buckle force of the stiff skeleton arch bridge with prefabricated bottom floor.Based on the existing buckle force calculation method,the displacement effect matrix is applied to the buckle force calculation of the stiff skeleton arch bridge with prefabricated bottom floor to solve the buckle force value that can meet the linear requirements of the main arch ring.(2)It studies on the linear control target for the installation of the stiff skeleton arch bridge with prefabricated bottom floor.Aiming at the problem that it is difficult to determine the linear control targets for the installation of rigid skeleton arch bridge with prefabricated bottom floor,based on the goal of the smallest sum of squared eccentricity of the arch ring section in the completed bridge state,the cable force formal installation calculation of the stiff skeleton arch bridge with bottom floor is carried out to solve the installation control line of the stiff skeleton arch bridge with bottom floor.(3)It analyzes the cause of excessive stress on the arch foot chord and solution.Aiming at the problem of excessive stress on the arch foot chord after installation of the stiff skeleton arch bridge with prefabricated bottom floor,this study analyzes the stress change process of the chord in the installation stage of the stiff skeleton arch,and proposes a solution to reduce the stress on the arch foot chord.(4)It studies outsourcing concrete pouring of stiff skeleton arch bridge.Based on the multi-face method and the continuous pouring method,fitting deflection influence line formula,the stress and deformation changes of the main arch ring under the different ring segmentation method by the multi-face method and the continuous pouring of the outer concrete of the arch ring adjusted by the diagonal cable buckle load adjustment are analyzed.The advantages and disadvantages of outsourcing concrete construction schemes are evaluated from five aspects: structure internal force,structure deformation,structure integrity,construction period and construction equipment in the construction of outsourcing concrete.