| The concrete-filled steel tubular column with outer U-shaped steel concrete composite beams is a kind of emerging steel-concrete composite structure in recent years.It has a lot of advantages such as high bearing capacity,good stability,convenient construction,high comprehensive and so on.So this structure has been more and more attention by the engineering and academia.In this paper,based on the research of partition through-type and steel truncated joint between the concrete-filled square steel tubular column and outer U-shaped steel concrete composite beams,a new type of joint is proposed to improve the mechanical properties of the joint between the negative bending steel bars and the steel pipepartition through and steel sleeve type joint.Then the ABAQUS finite element analysis software was used to study the shear behavior of the new joint.This paper has the following works and results:(1)Using the ABAQUS software to complete the finite element simulation of low-cycle reciprocating load with the partition through-type and steel truncated joint between the concrete-filled square steel tubular column and outer U-shaped steel concrete composite beams.The results of finite element analysis are in good agreement with the experimental results in the deformation,stress distribution,failure form,hysteresis curve and skeleton curve.(2)Based on the finite element model of verification,a finite element specimen with shear failure is designed for new joint of the specimen.Then the three-dimensional nonlinear finite element analysis is carried out to discuss the new joint of failure modes and joint deformation.The stress distribution law,force transmission mechanism and shear capacity of the new joint is analyzed accurately.Research indicates: The core area of the new joint is changed from the original rectangle to the parallelogram,and the joint has obvious shear deformation.The shear bearing capacity in the core area of the new joint is mainly borne by the core area of square steel pipe webs and concrete.Core area of concrete mainly formed the "oblique pressure rod" in the diagonal direction to resist the pressure at the edge of the beam;While the core area of the steel pipe column is mainly formed the "oblique pull rod" to resist the external force of the joint.(3)Parametric analysis of shear capacity of new joint is carried out to study the main factors affecting the shear capacity of the joint.Research indicates: The thickness of the concrete wing plate,the steel content of the steel cross section,the steel strength of column has greater impact on the ultimate shear capacity of the joint.The strength of the concrete column and the thickness of the penetrating plate have limited influence on the ultimate shear capacity of the joint.When the axial compression ratio is 0-0.3,the ultimate shear capacity of the joint can be improved when the axial compression ratio of the concrete-filled square steel tubular column increased to a certain extent.When the axial compression ratio is 0.3-0.6,the axial compression ratio has little effect on the ultimate shear capacity of the joint.The width of the concrete wing has little effect on the ultimate shear capacity of the joint.The calculation results of the simplified formula of the ultimate shear capacity of the new joint are in good agreement with the finite element calculation results and the simplified formula has certain applicability.(4)The simplified formula of the ultimate shear capacity of the new joint is proposed,and the calculation results of the simplified formula are compared with the finite element calculation results.They are in good agreement and have certain applicability. |
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