Study On Spatial Mechanical Properties Of High-strength Welded Hollow Spherical Joints

High-strength steel large-span space structure engineering is increasing day by day.Because of its novel and unique shape,high strength steel members are intersecting,joint welds are dense and the stress is complex.And there is a lack of relevant research on welded joints of high-strength space structure at present,especially the lack of design proposals to consider the spatial mechanical properties of high-strength welded joints.Therefore,this paper chooses welded hollow spherical joints widely used in long-span space structures as the research object.Based on the steel micro-damage and fracture prediction model,the spatial mechanical properties and damage mechanism of Q460 high-strength steel welded hollow spherical joints are systematically studied in order to provide scientific basis for the further development of long-span space structures.The specific work is as follows:(1)A high precision three-dimensional solid finite element model of welded hollow spherical joints is established by using ABAQUS program,considering weld and heat affected zone.Based on the refined numerical simulation technology based on the theory of micro-fracture prediction,several previous experimental results are reproduced,and the validity and accuracy of the numerical analysis method are verified.(2)System parameter analysis is carried out for the joint form of high strength steel positive quadrilateral pyramid grid structure.The stress distribution and deformation characteristics of welded spherical joints are investigated when the outer diameter of welded spherical joints,the thickness of welded spherical wall,the diameter of pipe,the angle of rods and the axial force ratio of rods change.The ultimate bearing capacity,stiffness and ductility response characteristics of joints under multi-directional loading in space and their main influencing factors are obtained.(3)The damage mechanism of spherical joints in space is clarified.A more accurate formula for calculating the bearing capacity of joints is proposed.