Study On Seismic Performance Of End-Plate Joint Of Hot Rolled H-Shape Column And Spliced Double-H-Shape Beam

In the Northridge earthquake in the United States and Hanshin earthquake in Japan,brittle damage occurred to a large number of rigidly connected beams and columns.At present,the research on the seismic behavior of beam and column joints is mainly focused on the single beam and column joints,but less on the double beam and column connecting through the end plate.In order to improve the efficiency of steel use and rational use of hot-rolled H-shaped steel,the research group proposed a joint form of hot-rolled H-shaped steel column and doublespelt hot-rolled H-shaped steel beam connecting through the end plate.On the basis of the research on the overall stability of hot-rolled H-shaped composite beams with high-strength bolts,the design and calculation of the new double-beam end-plate joint were carried out.Then,using ABAQUS finite element software to simulate the failure mode,equivalent plastic strain,bending torque-angle hysteresis curve,skeleton curve,bearing capacity,rotation capacity,ductility,stiffness degradation,energy consumption capacity,strength classification and stiffness classification of the three terminal plate joints,the performance of the new double-beam joints is proved to be excellent.Then,by means of finite element analysis,the influence of end-plate thickness,double-beam splice bolt spacing,endplate bolt spacing and edge pitch,column web-stiffening rib thickness on the seismic behavior of the new double-beam joint is investigated to determine the reasonable design parameters of the new double-beam end-plate joint.Finally,by analyzing the influence of the reduction of the cross section size of the lower beam and the reduction of the specification class of the bolts between the two beams on the mechanical properties of the joint,the further improvement measures are put forward.The main conclusions of this paper are as follows:1.When the traditional single beam joint fails prematurely,its seismic performance indexes are significantly reduced compared with those of the joint with the same beam section height and width.When the double-beam joints in the box joint domain fail,the end plates buckle and plastic hinge appears at the beam ends,which proves that the setting of the skin plate fails to increase the stiffness of the joint domain effectively.In this paper,obvious plastic hinge appears at the end of the new double-beam end-plate joint when it is damaged,and the joint domain still has relatively large strength and stiffness,which conforms to the structural seismic design concept of "strong Joint,weak member".2.The thickness of the end plate has a great influence on the failure form and seismic performance parameters of the joint.When the thickness of the end plate increases,the failure mode of the joint will gradually change from buckling failure of the end plate to plastic hinge failure failure of the beam end,and the classification of joint connection strength will change from weak connection to equal strong connection.When the thickness of the end plate is greater than or equal to the diameter of the bolt rod,the seismic performance indexes of the node are relatively good.It is recommended that the thickness range of the end plate be(d,d+3),where d is the diameter of the bolt rod.According to the European EC3 stiffness classification standard,the new double-beam end-plate nodes in this paper are generally semi-rigid connections,but when the thickness of the end-plate is too thick,close to or exceeding d+5,the node stiffness classification will be rigid connections.3.The thickness of column web stiffeners,the spacing of double-beam splicing bolts and bolt specification grade have no significant influence on the failure patterns and seismic performance indexes of joints.The first two values can be taken as the minimum values according to the structural requirements.It is suggested that the spacing of double-beam splicing bolts should be L/8～L/6,and L is the beam length.4.The increase of the middle distance of the end plate bolt can reduce the plastic strain of the end plate and increase the stiffness of the joint domain.The edge distance of end plate bolt will not affect the joint damage form and seismic performance,and the minimum value can be satisfied.5.When the lower beam cross-section in the spliced double beam is changed to a smaller size,the joint also has plastic hinge failure at the end of the beam,and also has remarkable "strong joint domain" characteristics.Although the mechanical indexes of the joint have decreased,it can still meet the specification requirements and be used in practical engineering.