| Circular hollow concrete-filled steel tubular composite column is a new type of composite structure,which has the advantages of high bearing capacity,good fire resistance and simplified construction.In this paper,the concrete-filled circular hollow steel tubular composite column-H steel beam joint is studied.The sleeve,outer ring plate and stiffener are used to connect the concrete column and H steel beam.The prominent advantages of this kind of node include convenient construction and clear force transmission path.With the widespread application of superposed columns of concrete-filled steel tube structures,it is of practical value to understand the mechanical properties of the nodes of this structure.In this paper,the characteristics of this node are studied as follows:(1)An experimental study of 4 circular hollow concrete-filled steel tubular composite columns-H-shaped steel beam joints under monotonic loading was carried out.The mechanical test device,measurement content and loading scheme were introduced.Three variables,namely,sleeve thickness,steel beam height and axial pressure ratio,were set to analyze typical test phenomena.By comparing the load-displacement curves of specimens,the influence of various variables on the ultimate load of components was analyzed.By comparing the curves of bending moment-angle,the influence of various variables on the ductility of core zone was analyzed.It is concluded that the height of steel beam has the most obvious influence on the ultimate load and ultimate bending moment of steel beam.Then,the strain load curves of upper and lower flange,column and outer ring plate were compared and analyzed.The increase of sleeve thickness has a significant effect on the stiffness of the joint,Finally,the shear shear deformation curve in the core area of the joint is drawn,which shows that there is no shear failure in the core area of the joint(2)The finite element software ABAQUS,which has the advantage of nonlinear processing,was used to build the analysis model of concrete column-steel beam joint of circular steel pipe with outer ring plate.Accurate constitutive relation was applied.Then contact and interaction were defined and monotonic loads are applied.Finally,mesh generation was carried out and the rationality of model solution is verified.Compared with the test results,the results show that the finite element component has good accuracy and reliability.(3)ABAQUS was used to analyze the whole process of the test specimen,and the load-displacement curve was compared with the test.The test deformation map was compared to verify the rationality and reliability of the model.Through the analysis of the whole process of the curve by ABAQUS,it deepens the cognition of the bearing capacity and failure form of each part of the node,understands the cooperative working characteristics of each part,and provides suggestions and guidance for the node design of this composite structure.(4)On the basis of the established finite element model,according to the results of the above analysis,purposefully set the internal steel pipe thickness,stiffener strength,web strength and other variables to further analyze the mechanical properties of the joint.Finally,combined with the test results and engineering actuality,a practical calculation expression for the joints is obtained,The calculated results of the formula are in good agreement with the experimental results,and the joint stiffness type analysis is carried out in combination with previous research results,it is concluded that the joint is semi-rigid. |
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