| The assembled steel structure is being widely used in high-rise buildings because of its advantages of environmental protection,high efficiency,low pollution and good seismic performance,which will become the mainstream structural form of the future building system.Compared with the H-shaped steel column,square steel column has same and larger rigidity in the two main axes,which can be better used in the high-rise buildings.On the basis of summarizing the new type of assembled beam-to-column joints proposed by many scholars at home and abroad,a new kind of assembled beam-to-column joint with C-shaped cantilever section was proposed in this paper.Low cycle repeated loading tests and finite element numerical simulation analysis were carries out,focusing on the seismic performance of the joint.The main research work and achievements are as follows:(1)Three groups of assembled beam-to-column joints with C-shaped cantilevered section were tested under low cycle repeated load.The failure mode and seismic performance of the joint were studied with the length of C-shaped cantilevered section and lower flange cover plate as control parameters.The test results indicated that this new kind of joint was semi-rigid,which consumed energy through warping deformations of end plate and the friction slippages between flange of beam,C-shaped cantilever section and cover plate.While realizing efficient assembly of square steel column and H-shaped steel beam,the stipulation of "strong joints,weak members" were satisfied,and the plastic hinge was guaranteed to move out.The hysteretic curves of the joints were relatively plump with a certain shrinkage at the zero point,which shows a good plastic deformation capacity.By reasonably increasing the length of the C-shaped cantilever section and the cover plate,it can ensure that the joints have high bearing capacities,while significantly improving the energy dissipation capacities of the joints.The ductility coefficients of the joints were greater than 3.0,and the equivalent viscous damping ratio were about 0.3-0.36,which indicate that the new type of assembled joints have good seismic performance.(2)Three finite element models based on the test specimens were established and simulated through ABAQUS finite element analysis software.The reliability and accuracy of calculation models were verified through comparing with the experimental results,and the numerical error was controlled within 15%,which indicated that the finite element models can better reflect the nonlinear deformation of the joint.In addition,the stress nephograms of three models at different rotation angles were analyzed,and the stress mechanism and internal force development trend of the joint under cyclic load were further determined.(3)the stress distribution of the three models at different displacements were analyzed,and the stress mechanism and internal force development of the joint under low cycle repeated load are further analyzed.(4)On the basis of experiment and finite element analysis,the static performance of assembled beam-to-column joint with C-shaped cantilever section was studied with 7 control parameters,such as thickness and width of flange plate on cantilever section,number of bolts on beam flange plate and so on,which indicated that increasing the thickness of C-shaped cantilever flange plate can effectively improve the stress concentration at the connection between the cantilever section and the column;the width of the cantilever section largely determined the initial rotational stiffness of the joint with the maximum variation amplitude of 18.1%,and the recommended value of that was consistent with the column width;changing the bolt number and the thickness of the end plate only affected the initial slip of the joint while the influence amplitude on the initial stiffness and ultimate bearing capacity of the joint was within 5%;The plastic hinge at the beam moved outward with the increase of the cover plate’s length,which can effectively utilize the plastic deformation capacity of the beam,while the stress between the cantilever section and the column also increased. |
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