| Because reinforced concrete arch bridges have unique advantages in mountainous valleys and other terrain conditions,highway bridges in mountainous areas in my country often use reinforced concrete arch bridges as their bridge types.In recent years,a number of reinforced concrete arch bridges have been built in the southwest mountainous area by the cantilever pouring method in China.This method can make the arch ring integral and beautiful in shape.However,with the increase of the span,the cantilever casting length of the arch ring increases,the cable force increases gradually,thus increasing the construction risk and the design difficulty of the anchor buckle system.Taking the Chongqing Municipal Education Commission’s scientific and technological research project “300m cantilever pouring reinforced concrete arch bridge design and construction key technology”(KJZD-K201900705)project as a basis,this paper proposes a construction method using the combination of cantilever pouring and rigid framework,taking a 300 m reinforced concrete arch bridge as an example.The force behavior analysis of the full bridge is carried out,and on this basis,the force behavior analysis of the steelconcrete composite embedded section is carried out.The main research contents as follows:(1)Aiming at the self-weight of single-box and double-chamber arch ring and the poor local stability of single box and single chamber,a new type of box section with longitudinal ribs at the top and bottom is proposed.Under the premise that the height of arch ring,the thickness of roof and floor and the thickness of web remain unchanged,through the stability analysis of arch ring under different longitudinal rib heights,the reasonable value of longitudinal rib heights is obtained,so as to improve local stability and reduce the weight of arch ring.A trial design of a 300m-level reinforced concrete arch bridge was carried out,and a study on the reasonable value of the key parameters of the arch ring was carried out,and the bearing capacity and stability of the entire bridge were checked in accordance with the current specifications.(2)In this paper,H-steel skeleton and concrete-filled steel tubular skeleton are taken as the research objects,and two kinds of skeleton structures are designed,aiming at the two rigid framework structures used in the design,the influence of the section steel framework and the concrete-filled steel tube framework on the stiffness of the arch ring is analyzed based on the stiffness equivalent theory,the stress and line analysis of arch ring in the construction stage of H-shaped steel frame and concrete-filled steel tube skeleton are carried out.(3)Aiming at the problems that the arch ring may have excessive stress and excessive deformation when the whole section casting method on stiff skeleton with outer-packed reinforced concrete,the buckle cable load adjustment method is proposed,and the influence matrix is used to find the buckle cable that regulates the arch ring stress and linearity,and develops H-shaped steel Analysis of the stress and deformation of the arch ring section of the skeleton and the concrete-filled steel tube skeleton during the concrete pouring process.(4)Based on the bond-slip theory of section steel and concrete,the length of the embedded section of section steel is determined.The large-scale finite element software ABAQUS is used to establish a local solid model considering the PBL shear connector and the stud connector,and analyze the shear bond form with strong shear resistance under the most unfavorable load.Research on the PBL shear connector parameters that affect the shear performance of the structure. |
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