Research On Local Structue Of Joint Section's Mechanical Behavior Of Cable-stayed Bridge With Steel-concrete Composite Beams

The hybrid girder cable-stayed bridge in the practical application of the engineering projects has become more and more widely.As the key part of hybrid beam,the joint section is often mixed with pressure-bearing type,tension type and fastener type.The connection structure is particularly complicated,and the requirements of the component are also higher.In this paper,the influence of the factors such as the size,stiffness and pitch of the steel-concrete composite section of the mixed-beam cable-stayed bridge on the axial sheer force of the joint section is studied.At present,many scholars at home and abroad have done a lot of theoretical and experimental research on the combination section,and have got many relatively mature theories.The author also continues to study on the basis of previous studies.The main research contents include:(1)Expounding the development course and present situation of cable-stayed bridge,introducing the construction and classification of steel-concrete composite beams,this article researches the composite section of the composite beam as a focus,by taking Chongqing rail link garden Gao Bridge as the engineering background.(2)The finite element model of the full bridge is established by MIDAS / Civil,and the force analysis in the bridge stage is simulated to obtain the internal force value and the displacement boundary condition at both ends of the joint section,so as to provide the basic data for the refinement of the joint segment.(3)The finite element model of steel-concrete joint is established by using MIDAS / FEA simulation software,and the force analysis of the components is carried out.The changes of the spacing and stiffness of the shear bond,the change of the length and height of the cell,the variation of the thickness of the bearing plate and the change of the length of the joint segment on the distribution of the axial force are studied,and puts forward some suggestions for the design of the local components of the steel-concrete composite section.Throughimg these studies,we can get the following conclusions:(1)With the increase of the cell height,the shear strength of the shear key in the cell and the joint will be reduced.(2)The increase in the height of the grid allows the load to shift faster from the steel structure to the concrete structure.And this effect acts on the whole bonding section.(3)The stiffness and spacing of the shear bond have a great influence on the shear force of the shear section.For the shear bond in a single direction,the higher the stiffness and spacing,the higher the shear force will be,but the corresponding integral distribution wiil be more uneven.(4)The thickness of the bearing plate has little influence on the joint.