| The composite concrete-filled steel tubular(CFST)column–H shaped steel beam system not only has the characteristics of high strength,ductility,plasticity,fire resistance and seismic performance of the composite CFST column,but also has the advantages of light weight,high strength and easy opening,a good development potential.At present,domestic and foreign research scholars have some research on the form of composite CFST column–H shaped steel beam connection joints,but there are still problems of complex connection structure and poor node performance,which hinders the development of the system to some extent.Therefore,based on the previous researches on the joints of CFST column-beam joints,a new type of integral external reinforcement ring composite CFST column-H shaped steel beam joint connection form is proposed in this paper,and its seismic performance is studied.The main research contents and conclusions are as follows:(1)The existing test members of the joint CFST column-H shaped steel beam joints are analysed by using ABAQUS that is finite element software.The simulation results are compared with the test results to verify the reliability of the software modeling results.(2)A new type of composite CFST column-H shaped steel beam joints of integral reinforcement rings and two ordinary composite CFST and H-shaped steel beam connection joints were designed.Seismic performance indexes such as failure mode,bearing capacity curve and energy consumption coefficient of the column-H shaped steel beam connection joints are compared with two ordinary composite CFST column-H shaped steel beam joints.Under the action of cyclic reciprocating load on the beam end,the hysteresis curve of the new composite CFST column-H shaped steel beam joints of integral reinforcement rings has good fullness,load-displacement curve and load-displacement curve shape of typical joints.The ductility coefficient is 3.99 and the energy consumption coefficient is 3.191,which indicates that the ductile performance and energy dissipation performance of the new node are better.Compared with the common nodes,the new joint plastic hinge has obvious outward shift,and various seismic performance indicators have been improved.Therefore,in actual engineering construction,the node has good promotion and application value.(3)The finite element models of 42 new composite CFST column-H shaped steel beam joints of integral reinforcement rings were established respectively.The axial compression ratio,the cylindrical ring diameter ratio and the overall external reinforcement ring length-thickness ratio were studied.The influence of the parameter variation of the beam flange width ratio,the beam-reinforcement ring height-thickness ratio and the beam flange weakening depth on the seismic behavior of the new integral outer reinforcement ring composite CFST column-H shaped steel beam connection joint.The results show:the axial compression ratio has a great influence on the failure mode of the joint.When the axial compression ratio is greater than 0.6,the column will be bent and unstable.The node will withdraw from the work early,and the axial compression ratio too small,which will lead to waste of building materials.The control is between 0.3 and 0.5;the ratio of the length of the ring to the diameter of 3.33 will result in poor ultimate bearing capacity and ductility of the joint.Below 1.52,the hysteresis curve of the node will be poor,and the energy consumption performance is not ideal.It is recommended that the ratio of the length of the ring to the ring is controlled between 1.85 and 2.38;when the ratio of the length of the outer ring is greater than 24,the plastic hinge of the joint will occur in the core area of the joint,and the seismic performance is not ideal.If it is less than 6,the steel will be wasted.It is recommended that the overall outer reinforcement ring length-thickness ratio is controlled between 6 and 12.When the beam flange width to thickness ratio exceeds 23.1,the ductility and energy dissipation performance of the joint will be poor.Below 11.5,the ultimate bearing capacity and initial stiffness of the joint will be caused.It is recommended that the width-thickness ratio of the beam flange is controlled between 15.4 and 19.2;the height-thickness ratio of the beam-reinforced ring exceeds 25,which will result in the node hysteresis curve being not full,the initial stiffness is too large,the ductility is poor,and the energy consumption performance is not ideal.Less than 15,the ultimate bearing capacity and initial stiffness of the joint are low.It is recommended that the beam-reinforcement ring height-thickness ratio is controlled between 15 and 22;when the beam flange weakening depth is greater than 80mm,the node hysteresis curve is not full and the initial stiffness is small.The energy consumption is poor,and it is recommended that the beam end weakening depth be controlled 0.13b_f and 0.26b_f(b_f-between the beam flange width).(4)In order to further study the seismic performance of the overall external reinforcement ring space joint,the finite element software was used to study the seismic performance of the new composite CFST column-H shaped steel beam joints of integral reinforcement rings.The results show:the failure mode of the new composite CFST column-H shaped steel beam space joints of integral reinforcement rings and the new composite CFST column-H shaped steel beam plane joints of integral reinforcement rings are the same,all of which are plastic end hinge failure of the beam end.The energy dissipation performance is better.Due to the spatial effect,the seismic performance of the spatial corner column,the middle column and the side column node is weaker than that of the planar node;the space effect has a greater impact on the seismic performance of the corner column node,but the influence of the middle column node and the side column node is small.Finally,some suggestions for the application of the new composite CFST column-H shaped steel beam joints of integral reinforcement rings in the space frame are put forward. |
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