Research On Static Performance Of Blind Bolt Connection Joints Of Assembled Steel Structure

The steel frame system is the most widely used structure type in the multi-layer assembly building.The most common form is H type steel beam column system with rigid connections or semi-rigid connections.The cold-formed pipe string and H type steel beam system is another common system,because its bi-directional stiffness are approached,the comprehensive cost of fire protection and anticorrosion is relatively low.However,due to the closed section of the cold-formed square steel tube column,the traditional high strength bolt can not be installed unilaterally,generally require field welding connection.In this paper,a blind bolt extension end plate connection node is proposed.This connection method can be operated on one side,it can be applied to the square steel pipe structure conveniently and quickly.Scholars at home and abroad have little research on the mechanical properties of blind bolt extension end plate connection joints,and it is difficult to popularize and apply in practical project.Therefore,it is of great significance to study the mechanical properties of the end plate connection joints with blind bolt.In order to get the mechanical properties,failure modes and influencing parameters of this new type of joint,the prototype test and finite element analysis of the single bolted endplate connection joint are carried out.The research contents and achievements are as follows:Monotonic static loading tests of 3 full-scale square steel tube columns with single bolt extended end plate connections are carried out.The test variables are the thickness of the end plate and the thickness of the column wall.The data of material constitutive relations,ultimate bearing capacity,stiffness and ductility of single bolted connection nodes are obtained.Research shows that the thickness of column increase can effectively enhance the stiffness and bearing capacity;end plate thickness reached 16 mm,increasing the thickness of the end plate only enhance joint stiffness,impact bearing capacity without joint moment;such nodes belong to semi-rigid connection nodes,high strength,good ductility,ultimate rotation requirements exceeded 5.08 rad.The finite element software ABAQUS is used to establish the finite element model of the single bolted extended end plate connection node,and the failure modes,stress distribution and change trend of such joints are obtained,and the workingmechanism of the joints is discussed.The results of the numerical simulation are compared with the test results,and it shows that the results of the finite element calculation have certain reliability.On the basis of the verification of the correctness of the finite element simulation,the working mechanism of this kind of node is further studied.The influence of the key parameters such as yield strength of steel,column axial compression ratio,end plate thickness,column thickness,bolt diameter and other key parameters on the mechanical properties of the joints,including the diameter of single side bolt and the thickness of column wall,is investigated.And the strength of steel clothing can significantly enhance the mechanical properties of joints.In the reasonable parameter range,three improvement measures for node construction are proposed: beam flange horizontal armpit,beam flange weakening,end plate setting stiffener.Based on the above research,it will provide reference for engineering design and construction.