Study On Bearing Capacity And Joint Stiffness Of Complex Structural Welded Hollow Spherical Joint

Welded hollow spherical joints are widely used in spatial grid structures because of their simple structure,convenient processing and high bearing capacity.Over the past 50 years,many scholars and engineers have made in-depth analysis and research on the traditional welded hollow spherical joints,achieved fruitful results,which have been widely applied to spatial grid structures.In practical engineering applications,many complex welded hollow spherical joints,such as H-beam welded hollow spherical joints,suspendome support joints and suspendome support upper joints,have emerged due to various types of members and special joint locations.Compared with welded hollow spherical joints with circular pipes at general locations,their bearing capacity,stiffness and joint design methods are quite different,and need to be systematically studied.On the basis of summarizing the previous research work,the mechanical characteristics and joint design methods of H-beam welded hollow spherical joints under axial and pure bending loads are studied.The mechanical characteristics of suspendome support joints and suspendome support upper joints are analyzed.The main research contents and conclusions are as follows:The mechanical properties of H-beam welded hollow spherical joints under axial compression are obtained by experimental research and finite element analysis.The failure modes of the joints under axial compression are obtained.The load-displacement curves,load-strain curves and degradation curves of axial stiffness under axial compression are analyzed.The influence of diameter D,thickness of welded hollow sphere t height of H-beam h and width of H-beam b on the bearing capacity and ductility of H-beam welded hollow sphere joints under axial compression are studied.Based on the finite element parametric analysis and theoretical derivation,the calculation methods of bearing capacity and initial axial stiffness of joints under axial compression and the critical elastic and elastoplastic deformation of joints under axial compression are obtained.The test,finite element simulation and parametric analysis of H-beam welded hollow spherical joints are completed.The failure modes,moment-nominal rotation curve,load-strain curve and degradation curve of bending stiffness of H-beam welded hollow spherical joints under pure bending load are obtained.The bending capacity and the initial bending stiffness of H-beam welded hollow spherical joints with diameter D,thickness of welded hollow sphere t height of H-beam h and width of H-beam b are analyzed.Based on the finite element parametric analysis,the calculation methods of the bearing capacity and the initial bending stiffness of the joints under pure bending load and the calculation formulas of the elastic critical deformation and the the critical elastic and elastoplastic deformation of the joints under pure bending load are obtained.The experimental study and finite element simulation of the suspendome support joints and suspendome support upper joints under bending moment,axial force and bending moment are carried out.The failure modes,bearing capacity and bending stiffness of the two kinds of joints under bending load and compression bending load are analyzed.