Mechanical Behavior Study On The Attachment Type Concrete-Filled Steel Tubular Lattice Wind Tower

Human exploration of wind energy applications has never stopped,and endless wind energy can provide new impetus to the development of the earth.With the continuous development of global industrial technology and the continuous emergence of larger wind turbines,these promote the continuous progress of support structures,and the traditional cone-tube tower has difficulties in transportation and installation after it has reached a certain height.Economics has fallen sharply as the wall thickness of cone barrels increases.In order to solve this problem,the lattice concrete-filled steel tube(CFST)wind power tower is proposed,and its bearing capacity and construction height are far higher than the traditional tower.At present,the research on lattice tower mostly focuses on the mechanical properties of welded intersecting joint and tube-plate joint.Can be used,but the node has high construction precision and higher requirements for field installation.In this case,the new type of attached node of the lattice type steel tube concrete wind power tower is proposed in this paper,and the fine work of the node can be completed in the factory,thus simplifying the on-site process and solving the problem of low construction efficiency.At present,the mechanical property and the damage form of the node are to be studied,and how to design in the project is also a major problem.In this paper,five scale models are made to the node,and the static loading method is adopted to load the joint.The following conclusions are obtained by the combination of the test data and the finite element software ABAQUS,The main results are as follows:(1)The 1.5 MW cone-tube wind power tower in Baiyun Obo area is taken as the design reference model.A three-leg concrete-filled steel tube latticed wind tower is designed.The internal force of tower frame is calculated by using SAP2000 general structure analysis software,and the internal force distribution law of tower frame and the most unfavorable position of tower joint are obtained.The research shows that the internal force of web rod is proportional to the height,and the force of transverse web bar in one node is almost weak.The main force is inclined web,and the ratio of tension andcompression is between 1.1 and 1.2.(2)When the thickness of the joint plate increases from 4 mm to 6 mm,the peak stress and deformation capacity of the joint increase by 90% and 140%,respectively.The change of the thickness of the joint plate can significantly improve the peak bearing capacity of the joint.When the web wall thickness increases from 4 mm to 6 mm,the peak stress of the joint increases by 12% and the deformation ability of the joint increases slightly,which indicates that it is not economical to control the wall thickness of the joint to improve the ultimate bearing capacity of the joint.The change of nodal plate thickness and web wall thickness changes the joint failure mode.The joint failure mode is divided into two types: the node plate collapses unsteadily along the compression tear line,and the high stress zone of the joint is mainly concentrated in the node.The high stress zone of the joint is mainly concentrated in the middle part of the web,and the stress concentration phenomenon of the joint plate is improved obviously in the intersection of the point plate and the compressed web,and the buckling in the middle part of the web is mainly concentrated in the high stress zone of the joint.It is suggested that the middle buckling of the web should be controlled when the joint is designed,and the properties of the material can be used to make use of the impingement.(3)Comparing and analyzing the web load-deformation curve,the web equivalent stress distribution curve,the node plate equivalent stress distribution curve,the attachment plate equivalent stress distribution curve,and the bolt slip detection curve of each specimen.The development process of stress and deformation and the location of stress concentration of each component of the joint are studied.The analysis shows that the equivalent stress distribution of each component of the new attached joint is more uniform,and the stress concentration in the compression zone of the joint plate is obvious,which is a weak component.(4)A new attached node model is established by using ABAQUS finite element analysis software.The finite element results are verified with the experimental data,andthe correctness of the model is verified.On this basis,two key parameters affecting the ultimate bearing capacity and failure pattern of joints,the ratio ? of attachment plate thickness to node plate thickness,and ? of node plate thickness to web wall thickness,are studied.The results show that in order to make full use of the material properties and ensure the safety of joints,it is suggested that ? should be 1.2 and ? 1.5.