Research On Mechanical Properties Of Inner And Outer Flange Connections Of Tapered Concrete-filled Double Skin Steel Tube Members

The tapered concrete-filled double skin steel tube is widely used in transmission towers,wind turbine support columns,and offshore platform columns due to its high bending stiffness and good mechanical properties.At present,relevant types of component connections are not given in related specifications.The specific design method of the nodes,and the reasonable design of the connection of the nodes is a problem that engineers pay attention to.through mechanical principle derivation and finite element analysis,The mechanical properties of the internal and external flange joints of the member under bending and axial tension were thoroughly investigated,and the practical calculation method of the bolt tension of the member nodes was initially determined.The main research contents of this article are as follows:(1)In order to be able to grasp the force performance of the component as a whole,this project selects the circular concrete-filled double skin steel tube as the research object,and uses ABAQUS finite element software to carry out numerical analysis to study the force mechanism and stress of this typical member.The distribution and failure patterns are compared with the theoretical calculation formula to verify the reliability of the circular concrete-filled double skin steel tube modeling.(2)Using finite element ABAQUS software,7 concrete-filled double skin steel tube inner and outer flange joints were established(among them,1 circular hollow steel tube,1 concretefilled double skin steel tube,5 cones with different hollow ratios and tapered concrete-filled double skin steel tube)are subjected to bending and axial tension for numerical simulation research.The stress distribution of the inner and outer steel pipes and the inner and outer flange plates during the whole process of the node is analyzed.The influence of hollowness and taper on the bending and axial tensile failure modes of joints was studied.And the influence of parameters such as taper,hollowness,concrete strength,flange thickness,bolt inner-to-outer margin ratio,bolt preload on the ultimate bearing capacity of the node was studied.(3)Based on the theoretical calculation and finite element method,the inner and outer flange joints of the tapered concrete-filled double skin steel tube are analyzed,and when the node is bent,the position of the node's rotation axis is determined when calculating the maximum bolt tension;when the node is subjected to axial tension When acting,determine the ratio of the internal and external bolt tension and the ratio of internal and external bolt prying force.