Research On Mechanical Performance Of Universally Wrapped Assembly Joints Of Lattice Concrete-filled Steel Tube Wind Power Tower

At present,most scholars mainly focus on intersecting nodes and tube sheet nodes in the research on wind power tower nodes.However,the intersecting joints have the influence of welding residual stress;the tube plate joints have the defect that the joint plate is easy to buckle.Based on the above problems,this paper proposes a new type of wind power tower assembly node,that is,the lattice-type concrete-filled steel tube universally wrapped assembly node,and uses a combination of experiment and numerical simulation to study the node.The results are as follows:(1)Taking a 1.5MW wind power tower in Baiyun Obo mining area as the research object,carry out tower design and load calculation.Use SAP2000 to analyze its internal force value and get the weak part of the tower.(2)The influence of the thickness of the ball table pressing plate and the thickness of the ball table wall on the ultimate bearing capacity and failure mode of the joint is analyzed.The results show that there are two failure modes for the joints,namely the buckling failure of the table pressure plate and the strength failure of the table material.The buckling failure of the table pressure plate is a plastic failure mode,and the strength failure of the table material is a brittle failure mode;the thickness of the table wall affects the node.The key parameter of the failure mode,the increase in the thickness of the table wall makes the node change from the brittle failure mode to the plastic failure mode;the thickness of the table pressure plate is a key parameter that affects the ultimate bearing capacity of the joint.When the table wall thickness is 8mm,the table pressure plate thickness increases from10mm to At 16mm,the ultimate bearing capacity of the joint is increased by 77.2%.(3)Analyze the axial force-displacement curve of the web member and the equivalent stress curve of each component.The results show that the axial force-displacement curve of the web member in the tension zone of all specimens is relatively complete,with obvious elastic and elastoplastic stages.The increase in the thickness of the pressure plate significantly improves the ultimate bearing capacity of the joint;the increase in the thickness of the table wall can effectively improve the deformation capacity of the joint.The maximum equivalent stress of all joint ball tables and nip ball tables appears on the side squeezed by the bolt ball.The equivalent stress increase of the nip table is more even than that of the tension table.(4)The finite element calculation results are compared with the test results.The comparison results show that the axial force-displacement curves of the web members and the ultimate bearing capacity of the joints are in good agreement,and the model establishment is more reasonable.The expansion analysis of the thickness of the ball table pressure plate and the thickness of the ball table wall is carried out,and the following conclusions are obtained: when the table wall thickness is greater than 7mm and the ball table pressure plate thickness is greater than 16mm,the increase in the ultimate bearing capacity of the joint is significantly reduced.It is recommended that in the actual design of the project,the thickness of the ball table wall is about 7mm,and the ball table pressing plate is about 16mm.