Study On The Mechanical Behavior Of The Flange Disk Ball Joints Of Lattice Wind Tower With Concrete Filled Steel Tubular

When the CFST lattice wind power tower is subjected to horizontal wind load,its equivalent force distribution is uniform,the overall reliability of the test piece is good,the transportation cost is low,and the field installation is convenient.At present,intersecting joints and tubular plate joints are widely used in the field of wind power generation in remote areas of China,but the welding process is high,so the overall construction quality is difficult to control when welding at high altitude.In view of the problems of the above two kinds of nodes,which greatly limits the promotion and use of wind power generation,it is urgent to find the appropriate node form.In this paper,a new type of fully assembled space truss structure bolt ball joint is proposed to solve many problems existing in the joint form at present.The push-pull static load test on the web member of two kinds of flange disk ball joints is carried out,and the finite element analysis of the joint model is carried out by using ABAQUS simulation software.The main contents and conclusions are as follows:(1)SAP2000 software is used to calculate the internal force of each layer of the designed four limb column wind power tower,and the internal force distribution law of the relatively unfavorable layers and the most unfavorable layers in the 16 layer tower and the internal force ratio of the compression and tension web members are obtained,which provides the theoretical basis for the flange ball joint test.(2)Based on the results of SAP2000,four flange spherical joints are designed and manufactured and tested.The effects of the height and thickness of the spherical groove on the equivalent stress distribution of the whole and each component of the two types of flange spherical joints are studied.At the same time,the effects of the position of the resultant force point of the web member on the whole of the test piece are also studied.The failure modes of double bolt ball joint can be divided into shear failure and extrusion failure;the failure modes of single bolt ball joint can be divided into four categories,including weld strength failure,tearing failure of base metal of ball groove pipe wall,buckling failure and extrusion failure of ball groove pipe wall.(3)Combined with the final phenomenon of the test and the stress characteristics of the two kinds of flanged spherical joints,the axial force displacement curve of the web member,the distribution law of the equivalent stress in the middle area of the compression and tension web member,the distribution law of the equivalent stress on the surface of the flange plate and the distribution law of the equivalent stress in the wall area of the spherical groove pipe are analyzed.Summary: the web member has good resistance to deformation and bearing capacity,the ball groove pipe wall and the weld at the ball groove are the key parts of the flange ball joint,and the ball groove pipe wall has better transfer load to the upper and lower inclusions.Compared with the four kinds of universal wrapped joints,the joints with good bearing capacity,low cost,easy installation and convenient transportation are selected to provide the best joint form for later assembling into four limb column tower.(4)Using SolidWorks software to carry out three-dimensional modeling of the designed nodes and import the ABAQUS analysis software to process the data of the wafer measurement and verify with the data obtained by ABAQUS to determine the accuracy of the finite element simulation.The finite element parameters of the single bolt spherical joint are extended to obtain the reasonable value range of the height and thickness of the spherical groove pipe wall.The simulation results show that: in the process of loading,the joints are the main load-bearing components,considering the cost and practicability,C30 filled concrete is selected as the core concrete of the tower column;in the design of the ball groove,the height of the pipe wall of the ball groove is 55-60 mm,and the thickness of the pipe wall of the ball groove is 8-10 mm;...