Analysis Of Mechanical Behavior Of Rectangular Concrete-filled Steel Tube Column-steel Beam Joints

Concrete filled steel tube structures are widely used in engineering because of their excellent performance.As a key part of the structure,joints play an important role in the safety and stability of the structure.In this paper,based on ABAQUS finite element simulation,the mechanical properties of concrete filled rectangular steel tubular inner diaphragm joints(common joints and reduced beam section connection)are studied,and the formula of the shear-bearing capacity of the joints is given.The main work and achievements are as follows:(1)The finite element simulation of concrete-filled steel square tubular column and steel beam joints in the literature test was carried out by using ABAQUS software,and the simulated data of skeleton curve and failure mode of joints were compared with the test results,which were in good agreement.The validated modeling method is applied to establish the common inner diaphragm joints,and the process of shear deformation and the rule of stress variations of the joints under loading are analyzed.(2)The mechanical properties of common inner diaphragm joints and reduced beam section connection(RBS joints)under the action of monotony and the circulating load are compared and analyzed.The results show that the shear-bearing capacity of RBS joints decreases significantly compared with common inner diaphragm joints,and the energy dissipation capacity and stiffness degradation have little effect,but the ductility of RBS joints is better.The influence of height-diameter ratio,hooping coefficient,material strength and axial loading ratio on the shear resistance of common joints is studied.The influence of three weakening parameters on the shear resistance of RBS joints is also analyzed,and the design suggestions for the parameter range of weakening size are given.(3)A direct shear model in the joint panels is established.On the basis of calculating the shear-bearing capacity of each shear member of the joint,the formula for calculating the ultimate shear-bearing capacity of the joint is synthetically obtained by combining numerical simulation with theoretical derivation.The comparison between the results of calculation and simulation shows that the formula presented in this paper can calculate the shear-bearing capacity of the joint more accurately.Thus,the research can provide some design advice for the engineering application.