Theoretical Study On Bearing Capacity Of Welded Cylindrical Hollow Hub Joints Under The Combined Action Of Bidirectional Axial Compression And Bending Moment

The node is the key part of the space structure to ensure the safe transmission of force.The welded cylindrical hollow hub node is one of the important node forms.It is shaped as a cylinder and welded by the hub steel tube and the end plate.The hub node has the advantages of simple structure,easy construction,and low steel consumption.However,there are few studies on the multi-directional force performance of the node at home and abroad.Therefore,this article takes the welding hollow hub node as the research object,and the specific research work is as follows:(1)According to the characteristics of the welded cylindrical hollow hub node in the reticulated shell structure of China State Construction Health Industry City in Hunan Province,the joint effect of two-way axial compression or two-way axial compression and bending moment is similar to that of the in-plane bidirectional axial compression.The rectangular steel tube hub node model is established using ABAQUS software to determine the optimum unfavorable bending conditions,and the rationality of the finite element model is verified through experiments.(2)The failure mode of hub joint is determined by nonlinear elastic-plastic finite element analysis under biaxial compression,out of plane bending moment and their combined action.The influence of joint geometry size,stiffener size,load ratio of main and branch pipes,eccentricity and other parameters on the bearing capacity of hub joint is discussed.(3)When biaxial compression and out of plane bending moment act separately,and the loads of main and branch pipes are equal,the theoretical analysis model of hub steel tube and end plate is established based on the failure mode of ribbed joint.The theoretical solutions of bearing capacity of hub steel tube and end plate are derived by means of yield line theory and plastic deformation theory.The recommended calculation formula of bearing capacity of ribbed joint is given by using fitting method,and the bearing capacity of hub steel tube and end plate is considered the influence of different loads on the bearing capacity of the joint is analyzed.(4)When the load and eccentricity of main and branch pipes are equal under the combined action of biaxial compression and out of plane bending moment,the theoretical calculation method of bearing capacity of welded hollow hub joint under compression and bending action is obtained according to the variation law of tensile stress near the joint and shear stress on the punching plane of hub steel pipe with eccentricity considering the influence of different angles between stiffener and main branch,load and eccentricity on the bearing capacity of the joint,the recommended calculation formula of the bearing capacity of the joint is given.The research results of this paper put forward more reasonable parameter values and calculation methods for hub joints under multi-directional stress,so as to accurately and safely predict the bearing capacity of the joints.Finally,the above research work is summarized and the problems to be solved in the research field of hub joint bearing capacity are proposed.