| The assembled steel reinforced concrete frame structure has the advantages of short construction period,high production efficiency,good engineering quality,energy conservation and environmental protection,as well as the advantages of high bearing capacity and good aseismic performance of the structure.its practical application prospect is broad.The integrity and seismic resistance of the structure are mainly affected by the connection form of the beam column joint,so it is very important to study the performance of the beam column joint under the low cycle reciprocating load.In this paper,the assembly SRC column steel beam joint of bolted,welded and bolted hybrid connection is studied by quasi-static test,and the assembly side joint of bolted hybrid connection is verified by ABAQUS software.Based on the effective model,the seismic performance of the assembly SRC column steel beam and its joint considering the combined effect of floor slab is systematically compared and studied;finally This paper discusses the influence of slab thickness,slab reinforcement ratio,slab width and column axial compression ratio on the seismic performance of the joint considering slab combination effect.The main conclusions are as follows:(1)Under the action of low-cycle reciprocating loading,the specimens of three joints with different connection forms all buckled and fractured at the flange connection plate of h-type steel beam.Slip occurs in hysteretic curve of PCBJ1 jointed node,and the hysteretic curve of PCBJ2 node is the worst among the three,and the hysteretic loop area of PCBJ3 node is the largest,indicating that PCBJ3 jointed joint has the strongest energy dissipation capacity,while PCBJ2 welded joint has the weakest.In terms of bearing capacity of joints,PCBJ2 welded joints are the largest,and PCBJ1 bolted joints are slightly smaller than PCBJ3 bolted mixed joints.(2)By using ABAQUS software to establish fabricated SRC column,steel beam finite element model boundary nodes,the nodes obtained under low cycle reciprocating load model of failure pattern,hysteresis curve,skeleton curve and the stiffness degradation is consistent with the experimental results,the veracity and reliability of this paper,the finite element model has been proved effective,for later under considering the effect of combination of floor slab fabricated SRC column-the study of steel girder node.(3)The assembled SRC column-steel beam joints considering the combined effect of floor slab greatly reduce the load on the upper flange connection plate and the core area of the node module of h-type steel beam,which improves the stability of the upper flange of h-type steel beam,but also causes the plastic area of the lower flange connection plate of h-type steel beam to increase and the buckling deformation is obvious.Compared fabricated SRC column-steel beam specimens,considering the effect of combination of floor slab specimens bearing capacity and rigidity were increased significantly,but the ductility factor and equivalent viscous damping coefficient decreases,and the loop stiffness is always greater than steel fabricated SRC column node,and with the increase of the number of cyclic loading stiffness degradation,node specimen fabricated SRC column-steel beam joints specimen eventually damage later,after the maximum bearing capacity,its strength degradation curve is smooth,strength degradation is not obvious.(4)The bearing capacity,initial stiffness and energy dissipation capacity of composite effect joints can be improved by increasing the thickness of floor.With the increase of the reinforcement ratio of floor slab,the bearing capacity and stiffness of joint specimens increase slightly,the energy dissipation capacity increases,and the stiffness degradation rate is similar,but the ductility is slightly worse.The bearing capacity,initial stiffness and energy dissipation capacity of joint specimens can be improved by increasing the floor width within the range of 600 ～ 1000 mm,but its ductility is weakened.In the range of 0.15 ～ 0.5,increasing the column axial compression ratio can improve the bearing capacity and initial stiffness of joint specimens,but accelerate the rate of loop stiffness degradation and energy dissipation of joint specimens.When the column axial compression ratio is less than 0.3,the ductility of joint specimen can be improved.Therefore,the column axial compression ratio should be reasonably controlled in design.The research results can provide theoretical support for practical engineering applications of fabricated frame nodes. |
