Research On Performance Of Continuous Collapse Resistance Of Steel Frame Structure With End-Plate Connection Joints

End-plate Connection Joint is one of the most common joints configurations used in steel structure.It is favored by engineers and researchers because of its simple structure,easy processing,standardized production,cheap construction and so on.There are also countless studies on its mechanical properties.In this paper,the joint stiffness and its influential factors are studied by finite element numerical simulation.The results show that the joint stiffness has a nonlinear effect on the static and dynamic analysis of the structure.Especially under the accidental load,the structure will produce a large dynamic response when the column suddenly fails and exits from the structure,and the end-plate connection joint has large influence on the continuous collapse performance of steel frame structure.The joint will produce large energy dissipation by its deformation after the column fails,improve the ductility of the structure and enhance the ability of the structure to resist continuous collapse.The main contents of this paper are as follows:(1)The finite element numerical simulation analysis of beam-column joint with end-plate connection is carried out,and the moment-rotation curve under unidirectional load and the hysteretic performance under cyclic load are studied.The results are in good agreement with the theoretical calculation results of Eurocode 3.At the same time,the finite element numerical simulation and comparison of the factors affecting the joint performance are carried out,such as stiffening rib,bolt diameter,end plate thickness and column web stiffener.The results show that the stiffening rib of column web can significantly improve the stiffness of the joint,and alleviate the stress concentration of the joint.In addition,the analysis shows that the end-plate connection joint has better hysteretic performance.So for structures with seismic requirements,the end-plate connections with end-plate stiffeners and column web stiffeners are recommended.(2)The finite element numerical simulation analysis of the continuous collapse resistance of rigid connections and end-plate connections is carried out,and the results show that the end-plate connections have a great influence on the continuous collapse analysis of steel frame structure.The end-plate connection can reduce the end-moment of the beam and increase the moment in the span and the axial force of the side column.The internal force and the dynamic characteristics of the structure show nonlinear relationship with the stiffness ofthe joint.At the same time,the analysis shows that the joint produces large deformation when the column fails,which satisfies the ductility principle of "Strong Joint and Weak Member" and improves the ability of resisting continuous collapse of the structure.Therefore,the semi-rigid characteristic of the end-plate connection should be fully considered in the design.(3)The failure time,member-failure location and braces of steel frame structure are analyzed by finite element numerical simulation in this paper,which are the main factors affecting the performance of continuous collapse of steel frame structure with end-plate connection joint.The analysis shows that it is reasonable and conservative to take 1/10 of the first cycle of the residual structure,and the dynamic response of the structure caused by the failure of the edge column and the corner column is huge,while the braces can effectively improve the continuous collapse resistance of the structure.(4)8 columns are removed by the method of removing the components respectively in this paper,and the continuous collapse analysis of the steel frame with end-plate connection joint connected with three-story in a logistics wholesale market is carried out.The analysis shows that the structure is prone to collapse continuously after removing the components.Braces are used to strengthen the structure to improve its ability to resist continuous collapse.