Study On Rotational Stiffness And Axial Compressive Bearing Capacity Of Prefabricated Steel Braced Joints In Support System

As a new type of support system,prefabricated steel braces have many advantages,such as high safety,convenient disassembly and construction,shortened construction period,environmental protection and high economy.Due to the lack of research on the bracing,the research on the bending stiffness of the steel bracing with bolt connection between the cover plate and the end plate is not perfect,and the stress condition of the joint is still to be studied.Therefore,in this paper,the bending stiffness and axial compression bearing capacity of prefabricated steel braces with bolted joint are studied in depth,which plays a better role in promoting the application of the support system.In this paper,the structure,construction and application of the support system are introduced firstly,and then the flexural performance of the assembled steel braces is tested.On the basis of experiment,using the finite element software ABAQUS to establish finite element model of 11 with stitching node of prefabricated steel plate bolt support for simulation and parameter analysis,contrast with the experiment,respectively study the node connection plate thickness,friction coefficient,the numerical size of Pre-tightening force the rotational stiffness of this kind of steel support;Considering the semi-rigidity of the joints,20 finite element models were established to consider the influence of different spans,spacing,rotational stiffness of the joints and column arrangement on the axial bearing capacity of the assembled steel braces.Through the simulation analysis,two kinds of optimization methods for the design of assembled steel braces are proposed,and nine finite element models are established for simulation verification,which can provide reference for the design of steel braces.Research shows that:the H-beam section member through the cover plate and end plate with high strength bolts joining together of semi-rigid nodes,in the process of bending,the main elastic stage,stage of bolt slip and compression plate pressure phase,pressure plate sliding stage,the tension zone of the end plate and plastic deformation stage,stage of compression plate appear slip and artifacts as a whole into the plastic deformation is larger for the overall destruction of six phases;The preloading force and friction coefficient can improve the rotational stiffness and slip load of the joint,but can not improve the ultimate bearing capacity of the structure.The thickness of the cover plate can improve the rotational stiffness and ultimate bearing capacity of the joint.The stiffness of the bolt joint of the cover plate with steel support should not be too low.When the stiffness is lower than a certain value,the stability of the extreme point of the steel support will occur,and the bearing capacity will decrease greatly.It can be seen from the analysis that the length of steel braces is not good either when it is long or short,and it is the best when it is 3.5m,which increases by 50%relative to 2m and 5m,and is in approximately positive linear correlation with the joint stiffness.The axial compression bearing capacity increases by 10%when the joint stiffness increases by10,000k N·m·rad^-1,and the bearing decreases with the increase of bar spacing.In the design process of the steel support,the position of the column should be arranged close to the joint with the bolt of the cover plate,and the steel support should be set with oblique crossbar.The above two measures can prevent the instability and failure of the steel support.