Numerical And Experimental Study On Welded Hollow Spherical Joints Strengthened By External Triangular Rib

Welded hollow spherical joints（WHSJs）are widely used in space grid structures because of their simple structure,convenient connection and clear force transmission.Regarding the mechanical performance of WHSJs,scholars at home and abroad have conducted in-depth theoretical analysis and experimental research,and established a relatively complete calculation method of joint bearing capacity.However,the current research on the reinforcement of existing WHSJs is not thorough and comprehensive,and the calculation of the bearing capacity of reinforced WHSJs in the current specification is simply multiplied by an increase factor.Especially with the continuous development of novel nodes,this limitation has become increasingly prominent.In this paper,combined with previous research experience,the bearing capacity of WHSJs strengthened by external triangular ribs under unidirectional load was analyzed by finite element method and experimental study.In this paper,through experimental research,the WHSJs strengthened by external triangular ribs before and after the reinforcement of the comparative analysis of the bearing capacity,intuitive understanding of the stress development and failure forms,while verifying and verifying the correctness of the finite element model.In this paper,the numerical model of WHSJs by external triangular ribs is established based on the finite element simulation software ANSYS.The constitutive relation of steel adopts the ideal elastic-plastic stress-stress relationship,chooses VonMises yield criterion and considers the influence of geometric nonlinearity,and makes a systematic finite element analysis on the axial compression bearing capacity of WHSJs strengthened by external triangular ribs.The Newton-Raphson method is used to solve the load-displacement curve of the joint,and the influence of geometric nonlinearity on the ultimate bearing capacity of the joint is investigated.The difference of mechanical properties under axial compression and axial tension is compared,and the stress development process of the joint is analyzed,which reveals the mechanical properties and failure mechanism of WHSJs strengthened by external triangular ribs.Finally,224 groups of WHSJs strengthened by external triangular ribs under unidirectional load are numerically simulated and analyzed,and the influences of thickness,height,number and angle of triangular ribs on the bearing capacity of the joints are investigated.The calculation method of improving coefficient of WHSJs strengthened by external triangular ribs is put forward,which provides a reference for calculating the bearing capacity of WHSJs strengthened by external triangular ribs.