Study On Mechanical Properties Of Side Column Joints Of New Modular Hoop Outer Sleeve

In recent years,with the Chinese government’s vigorous advocacy of prefabricated steel structure buildings,residential industrialization has gradually become the development trend of China’s construction industry,and modular steel structure buildings,as a highly integrated prefabricated building form,have attracted widespread attention from the society with their outstanding advantages such as green environmental protection,fast construction speed and high degree of industrialization.Modular building is the factory prefabricated module unit transported to the construction site,and then assembled by the connection between the units of a building system,the form and performance of the connection node between the units will directly affect the safety of the entire structure,at present,the steel structure modular node generally needs on-site welding,complex connection components,insufficient node versatility,beam and column stress members on the opening and other problems,not only affect the assembly efficiency of the construction site,but also affect the safety performance of the building structure.In view of the above problems,the research group designed a new type of ring hoop outer sleeve connection node,which can be applied to different positions such as corner column,side column and middle column in the frame structure,which has the advantages of no welding,wide application range and convenient installation.The finite element software ABAQUS was used to establish the node model,and the stress distribution and failure form of the new type of node under the parameters of changing the node outer sleeve height,outer sleeve thickness,column end axial compression ratio,outer ring plate angle and column wall thickness were studied by applying unidirectional displacement load and low cycle reciprocating displacement load respectively.And a total of 10 groups of 36 node specimens were designed for the two loading systems.and the mechanical properties of the nodes were compared and analyzed from the aspects of bearing capacity,hysteresis curve,skeleton curve,energy dissipation capacity and stiffness degradation curve by applying unidirectional displacement load and cyclic reciprocating displacement load respectively.Under the unidirectional displacement load and low cycle reciprocating load,different degrees of failure and stress concentration occur at the beam-column connection weld,the beam end loading point area,the connection between the outer ring plate and the rib plate,and the corner of the outer ring plate of each node.Increasing the height of the outer sleeve,the nodal hysteresis loop area gradually increases,the equivalent viscous damping coefficient also increases significantly,the node energy consumption capacity is gradually enhanced,while the bearing capacity of this series of nodes increases less,and the initial stiffness of outer sleeve height250 mm is smaller than that of other nodes.Changing the thickness of the outer sleeve,the hysteresis curve of each node is fusiform,the equivalent viscous damping coefficient curve shows a uniform upward trend,the seismic performance of this series is relatively good,but the effect on the bearing capacity of the node is not obvious,and the equivalent viscous damping coefficient and stiffness of outer sleeve thickness10 mm are lower than that of other nodes.Changing the axial compression ratio of the column end has a great impact on the hysteresis performance,energy dissipation capacity and bearing capacity of the node,increasing the axial compression ratio of the column end,the hysteresis loop area of the node gradually decreases,and the energy dissipation capacity shows a downward trend,and in the loading process,the column end axial compression ratio 0.6 node is the first to reach yield,and the stiffness degradation rate is faster.Changing the angle of the outer ring plate,the hysteresis curve and skeleton curve of each node have a high degree of coincidence,the bearing capacity change range is small,the initial stiffness and stiffness degradation trend of each node are basically the same,and the seismic performance of this series of nodes is good.Increasing the thickness of the square steel pipe column wall has no obvious law on the mechanical properties of the joint,but reducing the thickness of the column wall will reduce the energy dissipation capacity and bearing capacity of the node,which is more unfavorable to the seismic performance of the node.