| In this paper,combined with the advantages of mechanical properties of precast reinforced concrete beams and steel tube concrete columns,a new prefabricated reinforced concrete beam-steel tube concrete column assembly joint is proposed,in which the steel tube wall is perforated at the position where the beam longitudinal reinforcement passes through,so that the beam longitudinal reinforcement passes through the joint,and the steel tube wall is bolted to the U-shaped plate at the beam contact surface.The seismic resistance of precast reinforced concrete beam-concrete filled steel tubular column joints is simulated and analyzed by finite element software,and the influence of different parameters on seismic resistance of joints is further discussed.The main contents and achievements of this paper are as follows:1.Apply ABAQUS finite element software,analyze the selection,boundary conditions,load and grid division of the simulated test piece,establish a finite element three-dimensional model,and compare the finite element model results with the test,the anastomosis is high,Verify the correctness of the model and the reliability of finite element software.2.In the verification of finite element correctness,further expansion analysis,with beam concrete strength,beam trenchin reinforcement rate,U-shaped sheet yield strength and thickness,steel pipe strength and beam ribs diameter to test 14 models,design 14 models Analysis on the influence of nodes.3.The influence of each parameter on the seismic performance of joints is as follows:(1)with the increase of the concrete strength of the beam,the energy consumption of the joint increases,the concrete strength increases from C30-C60,the bearing capacity increases by about 3%,the ductility coefficient increases with the increase of the concrete strength,the LH-C50 stiffness degrades most rapidly,and the difference of the other three concrete strength is small.The concrete strength of the joint beam is suggested to be C30.(2)When the reinforcement ratio is 1.05%(LPJ-3),the hysteretic curve area is the largest,and when the reinforcement ratio is 0.95%(LPJ-1),the hysteretic curve area is the smallest,especially under reverse loading.The hysteresis loop area and peak load of LPJ-2(0.77%)are larger than those of LPJ-1.LPJ-2 is the fastest and LPJ-3 is the slowest in the early stage of stiffness degradation.LPJ-2 gradually slows down in the late stage of displacement deformation,and finally the stiffness degradation coefficient is the smallest.It is suggested that the longitudinal reinforcement 5C25 3/2 be configured at the upper beam.(3)By analyzing the parameters of five U-shaped plates,it is found that U-shaped steel plates play a very good role in transferring shear force between beams and round steel tube columns,but improving the strength and thickness of U-shaped plates has little effect on the seismic resistance of joints,so it is recommended to take Q345 grade steel with a test value of 8mm thick.(4)The strength of steel pipe is compared with Q390 and Q420.Compared with Q345,the strength of steel pipe Q390 is slightly improved,while the hysteretic curve of specimens with Q420 is enlarged and ductility is improved.The strength grade of round steel pipe below Q420 has little influence on the seismic resistance of joints.It can be seen that the strength grade of round steel pipe should be above Q420 to improve the seismic resistance of joints.(5)Three models with stirrup diameters of 8mm,10 mm and 12 mm are established for comparative analysis of beam stirrups.With the increase of stirrup diameter,hysteresis area decreases,bearing capacity increases,ductility decreases and energy consumption decreases.It is suggested that the stirrup diameter should be 8 mm. |
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