| In the process of promoting energy conservation and emission reduction in China’s construction industry,steel structure buildings have developed rapidly with the advantages of high strength,light weight,large ductility,high industrialization integration,good seismic performance,fast construction speed,sustainable development,good comprehensive economic indicators,etc.The application demand of steel pipe and box section column beam is increasing significantly,but the joint connection mode is still lack of research,the existing full welding and bolt welding connection methods can not be assembled at high speed,and can not meet the engineering application demand.This paper proposes a new type of box section beam square steel pipe column horizontal end plate bolt connection frame node,which is conducive to processing,transportation and hoisting in the factory,and can greatly improve the installation efficiency and effectively reduce the difficulty of installation and construction,so as to save energy and materials.The hysteretic curve,joint deformation,stress distribution,rotational stiffness,ultimate bearing capacity and failure characteristics of the box section beam square steel tubular horizontal end plate bolted frame joint under the action of low cycle reciprocating load are studied by the method of 1:1 solid component low cycle repeated load test and finite element numerical analysis.The results are compared with those of the traditional inner diaphragm box section beam column joint Finally,the feasibility of the application of this new type of node is investigated.The results are as follows:(1)The low cycle cyclic loading tests were carried out on the box section beam square steel tube short column double end plate bolted connection node and the conventional box section full welded connection node respectively.It was found that the stress concentration of the weld joint in the beam column connection area of the conventional box section full welded connection node was obvious,and it was easy to occur brittle fracture.The box section beam square steel tube column horizontal end plate bolted connection node effectively improved the node At the same time,it has better energy dissipation capacity and stiffness degradation coefficient.And the ultimate bearing capacity of the bolted connection of the box section beam square steel tubular column is 16.18%higher than that of the conventional welded connection.(2)Through ABAQUS The finite element software establishes the nonlinear finite element calculation model of two kinds of joints.The comparative analysis of the finite element numerical simulation results and the test results shows that the stress nephogram and the equivalent plastic strain of each component in the finite element numerical simulation are close to the test phenomenon of the corresponding component in the test,and the parameters such as the ultimate bearing capacity and the ultimate displacement of the joint are similar.Comparing the two kinds of joints under the low cycle reciprocating numerical simulation load,the seismic performance of the box section beam square steel tubular column horizontal end plate bolted joint is better than that of the conventional box section all welded joint,in which the yield load is increased by 29.3%,the ultimate load is increased by 22.7%,and the ultimate displacement is increased by 25%.The new joint has better seismic performance,which is consistent with the test results.(3)According to the results of the finite element numerical analysis and the low cycle reciprocating loading test,the parameters such as the component size,the axial compression ratio and the interface friction coefficient of the reference model are changed,and the influence of the parameter changes on the displacement load curve and the skeleton curve of the new joint is studied.It is concluded that the stiffener between the column and the end plate must be set in the node design to keep the axial compression ratio of the column end as much as possible In the range of 0.3-0.4,the thickness of the horizontal end plate should not be less than 16 mm,and the interface friction coefficient between the horizontal end plates has little effect on the bearing capacity and seismic performance of the joint.(4)Combined with the experimental research and finite element numerical simulation results,the practical engineering design and calculation methods of horizontal end plate,bolt and short column section of new steel frame joints are proposed. |
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