| Steel structure has the advantages of light weight and good seismic performance.The steel has the advantages of high strength,good plasticity and toughness.It is widely used in civil and industrial buildings.The beam-column connection is a key part of the building structure,it plays an important role in the structure to connect beam and column,to transfer and distribute the internal force of the structure,to coordinate the deformation between the structure and the components,and to ensure the Structural integrity.The earthquake showed that once the beam-column connections are destroyed,it will cause structure damages.Therefore,it is necessary to study the seismic performance of the beam-column connections.In this paper,a new kind of beam-column connection with upper flange welded-lower flange bolted improves from the“HU”connection.The upper flange of the connection is connected by butt weld,while one side of the lower flange is connected by fillet weld and the other side by bolt.In order to study the sequence of plastic hinge and splicing slippages,the proportion of energy dissipation of splicing and mechanical performance of the connection,four groups of tests were designed by changing the non-splicing length of cantilever beam,cross-sectional area of splice plate,friction coefficient and number of flange bolts.The finite element analysis of this new connection under monotonic and low cycle reversed loading is carried out with the ABAQUS software.In addition,the seismic performance of beam-column connection with upper flange welded-lower flange bolted and“HU”connection under different cross-sectional area of splice plate and friction coefficient are compared.At the same time,the seismic performance of BASE specimen of beam-column connection with upper flange welded-lower flange bolted and traditional connection are also compared.The results show that:(1)Under low cycle reversed loading,the failure modes of beam-column connection with upper flange welded-lower flange bolted under different splicing parameter are similar.The lower flange and the splice plate begin to slip,and then the plastic hinge appears on the cantilever beam.With the increase of the interstory drift angle of beam end,the plastic deformation zone and the slipping of splice increase.The connection can utilize the slipping of splice,the squeezing between the bearing of bolts and the hole-surfaces,and the deformation of plates to dissipate energy effectively,and the connection has a good hysteretic performance and energy dissipation.(2)With the increase of the non-splicing length of cantilever beam,the corresponding load and displacement increase when the splice plate begins to slip,but the proportion of energy dissipation of the beam splice decrease.On the basis of comparative analysis,it is suggested that the length of non-splicing length of cantilever beam is 1.25b_f~1.5b_f.When the cross-sectional area of splice plate is 2/3~4/3 times as large as the flange,the energy dissipation of the deformation and the slipping of splicing account for 39%~45%of the total energy dissipation.With the increase of the cross-sectional area of splice plate,the negative bearing capacity and ductility of beam-column connection with upper flange welded-lower flange bolted decrease.Thus,the appropriate reduction of the cross-sectional area of splice plate can improve the deformation and ductility of the connection effectively.(3)When the number of flange bolts is 2/3~4/3 times as many as the equal strength design,the energy dissipation of the beam splice accounts for 41%~44%of the total energy dissipation.With the decrease of the number of flange bolts,the bearing capacity of the connection decreases slowly after the load reached the ultimate bearing capacity.Therefore,the appropriate reduction of the number of flange bolts can increase the slipping of splice,the squeezing between the bearing of bolts and the hole-surfaces,and the deformation of plates.When the friction coefficient is from 0.1to 0.45,the energy dissipation of the beam splice accounts for 41%~48%of the total energy dissipation.With the decrease of the friction coefficient,the equivalent viscose damping coefficient of connection decreases,but the ductility of the connection is increased to some extent.(4)When the cross-sectional area of splice plate is 5/6~6/5 times as large as the flange,the plastic deformation of the cantilever beam with beam-column connection with upper flange welded-lower flange bolted is larger than that of the“HU”connection,but the ductility and bearing capacity are lower than that of the“HU”connection.Compared with the“HU”connection,beam-column connection with upper flange welded-lower flange bolted has good ductility when the friction coefficient is from 0.1 to 0.2;the ductility and deformation capacity of beam-column connection with upper flange welded-lower flange bolted are lower than that of the“HU”connection when the friction coefficient is from 0.3 to 0.45.(5)Compared with the tradition connection,the BASE specimen of beam-column connection with upper flange welded-lower flange bolted has high ductility,bearing capacity and deformation capacity. |
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