Experimental Study on Shear Performance of New Type of Aluminum Alloy Flower-Gusset Joint

Single-layer aluminum alloy latticed shell has many advantages such as light weight,corrosion resistance and beautiful shape,which has been widely used in large-span spatial structures in recent years.Because of the simple structure and convenient installation,plate joint has become one of the most commonly used joint forms of single-layer aluminum alloy reticulated shells.However,because the joint is only connected with the flange of aluminum alloy beam through the cover plate,but not connected with the web,the shear bearing capacity and in-plane axial stiffness of the joint are seriously insufficient and prone to instability and failure,which can not meet the performance requirements of large-span aluminum alloy reticulated shells.In this paper,on the basis of the existing joints,a new type of flower-gusset joint is proposed.In order to explore the shear performance and failure mode of the new aluminum alloy flower-gusset joint,the shear tests of the new type of joint and the traditional plate joint are carried out in this paper.The failure modes and load-displacement curves of the two joints under the out-of-plane load are obtained,and the shear performance of the new type of flower-gusset joint is analyzed.ABAQUS software was used to conduct numerical simulation analysis on the whole loading process of the new type of joint,and the reliability of the finite element model was verified.The results show that the failure mode of plate joints is mainly the tensile-shear failure of the cover plate,and there is no obvious bending failure of the aluminum alloy beam.The failure mode of the new type of joint is mainly manifested as the bending failure of the aluminum alloy beam,the warping of the cover plate and the tearing of the flower-gusset,which is mainly due to the effective sharing of the flower-gusset in the new type of joint and the transfer of a large part of the shear force.The flower-gusset changes the force transmission mode and failure mode of the traditional plate joint,and the aluminum alloy beam webs are connected through it to form an integrated body,which more effectively shares and transmits the shear force,reduces the shear load of the cover plate,improves the shear performance of the joint,thus changing the shortcomings of the brittle failure of the plate joint,so that it has good ductility and energy dissipation capacity.Therefore,compared with the traditional plate joint,the shear bearing capacity of the new joint is increased by 47.4% and the shear stiffness is increased by 103.9% due to the addition of the annular groove in the central area of the new joint,which has a good prospect for engineering application.The finite element analysis results of the new joint show that the linear segment of the load-displacement curve obtained by the finite element analysis is in good agreement with the measured displacement,the error is less than 5%,and the error of the shear bearing capacity is only 0.14%,which verifies the reliability of the finite element simulation results.When the new type of joint is subjected to the ultimate load,the partial stress of the upper and lower cover plates connected with the bar is large.However,most areas of the upper cover plate are plastic,and only a small part of the lower cover plate is plastic.Stress concentration occurs at the bolt hole and the junction of the ring tooth and the groove body.