Research Of Tubular KX-Joint

Steel tubular joint is one of the primary form of node in pipe structure. It has many advantages. Such as simple structure, artistic modeling and connected without bridge piece. It also saves material and owns good stress property and high ultimate strength. With the development of tubular cuts technical and steel products welding technology, the tubular joint has already more and more been used in various buildings. In the space of nodes, the tubular KX-Joints is a basic form and usually appears in the node spot where supports outside in the main and the secondary truss intersection or the joint face. But at present, there are no such kind of joint form supporting capacity formula in the standard, so study on each stress property to guide the engineering practice has great significance.Because in the region where the node is ,there geometry and material properties is complex and stress concentration is serious, ultimate strength is an important issue in the structural design. When the load is small, certain positions of node region have submitted and enter the plasticity, and causes the stress to distribute anew. In addition, the form of tubular joint is various, the stressing situation is complex, and the impact on the property is great, so strength property is more difficult to grasp. Therefore after summarizing the research technique and the achievement of domestic and foreign scholars in the study of this domain, in view of tubular KX-joint under axial force and moment in actual project, considering all the welded defects, this paper use nonlinear finite element analytic method with shell elements and solid element to simulate the tubular KX-joint in steel structures with deep research.First, under axial force, the author consider the mutual influence of space bars, analysis the failure mode of non-flaw tubular KX-joints, the stress distribution, the expansion of plastic region, the deformation of node and other important mechanical properties, and calculate the ultimate strength. Then assumes the situation with various welded defects existed, and use the different hollow shapes to simulate these defects' influence of the joint's ultimate strength, and we know that it is allow a certain size of welded defects existed. Finally, under the moment in and outside the plane, consider X branch and several immeasurable parameters' influence, obtains the destruction pattern, the elastic-plastic developing process and the ultimate moment strength. In this case, supposes welded defects existence and analysis the influence of the ultimate moment strength.