Research On Bending Capacity Of H-shaped Beam To Tube Column 3D Joint With Cast Steel Stiffener

As the hinge of force transferring of the steel frame structure and the constraints of various components,the beam-column joints have a significant influence on the bearing capacity of the frame structure.The traditional research project of mechanical properties of beam-column joints focused on the 2D beam-column joints.In actual engineering,most of the beam-column joints are 3D joints,which are subjected to bidirectional loads.The mechanical properties of 3D beam-column joints are often different from those of 2D joints subjected to unidirectional loads in its actual use.In this paper,the square tube column and the circular tube column H-shaped steel beam beam-column joint 3D cast steel joints are taken as the research object.A series of analysis and research were carried out to find out the flexural bearing capacity of the joint under the bidirectional symmetrical bending moment and the bidirectional arbitrary bending moment loading conditions by the finite element simulation method and the theoretical analysis.(1)The failure mode of H-shaped beam to square tube column joint with cast steel stiffener under the bidirectional symmetrical bending moment is analyzed by using the finite element simulation combined with the micro-body stress analysis method.Analysis shows that the material failure in the corner region of the cast steel stiffener caused the joint to yield.Based on the above failure mode,the theoretical calculation formula for the flexural capacity of square tube column joints based on Von Mises yield criterion is proposed.(2)According to the force characteristics of the cast steel H-shaped beam to circular tube column 3D joints under the bidirectional load,the micro-body stress analysis method and the improved yield line theory are used respectively to analyze the force mechanism of joints under the bidirectional symmetric bending moment.Based on the analysis results,the theoretical calculation formulas of the tensile bearing capacity of ring plate of cast steel stiffener and the tensile bearing capacity of the shell of circle tubular steel column under the bidirectional load are proposed.After the combination,the formula of bending capacity of the cast steel H-shaped beam to circular tube column 3D joints is obtained.(3)Through the finite element parametric analysis,the theoretical validity of the cast steel H-shaped beam to square and circular tube column 3D joints is verified,and the reduction of the bearing capacity of the 3D beam-column joints compared with 2D beam-column joints was analyzed.For the cast steel H-shaped beam to square tube column 3D joints,the results of finite element method shows that the flexural capacity of the 3D joint is reduced by 16.6% compared with the 2D joint,the results of theoretical analysis is 18.4%,a difference of about 1.8%;For the cast steel H-shaped beam to circular tube column 3D joints,the results of finite element method shows that the flexural capacity of the 3D joint is reduced by 27.5% compared with the 2D joint,the results of theoretical analysis is 31.2%,a difference of about 3.7%;and the coupling effect of the bidirectional bending moment on the joint is significant.(4)Through the finite element numerical simulation method,the change law of the cast steel H-shaped beam to square and circular tube column 3D joints under random bidirectional bending moment is analyzed.Based on the change law of the flexural capacity of the joints,the Lagrange linear interpolation method is used to propose the theoretical calculation method for the flexural capacity of the cast steel joints of the cast steel H-shaped beam to square and circular tube column 3D joints under random bidirectional bending moment.It provides a reference for the research and design of the bending capacity of joints under similar conditions.