Study On The Effect Of Pretension On The Mechanical Properties Of Blind Bolt T-stub Joint

Prefabricated steel structure building is a kind of prefabricated building which meets the demand of new building industrialization development.Beam-column connection is always a key link that affects structural performance,constructability and fabrication and installation cost.Fully-bolted connection between open section beams and hollow steel tubular columns or concrete-filled steel tubular columns has become a research hotspot in the field of building steel structures in recent years.The blind bolt,which can be installed on one side of the column wall and tightened on one side,has attracted widespread attention from scholars and engineers at home and abroad,especially for self-locking blind bolt,a large number of experimental studies and numerical simulation analysis on end-plate connection,T-stub connection and other beam-column joints have been carried out.The pretension of high-strength bolts has an important effect on the performance of the joint and is generally controlled by tightening torque.The working mechanism of blind bolts is different from that of ordinary high-strength bolts.Under the action of the same tightening torque,the values of pretension of blind bolts are different.Choose blind bolt Hollo-Bolt with more domestic and foreign research study,finite element simulation of blind bolt unilateral tighten,blind bolt tightening torque and bolt pretension and explore the relationship between the sleeve opening Angle,simplify the square steel tube column and H type steel beam overhanging end plate blind bolt connection nodes for blind bolt T-stub connection nodes,The joint was simulated by finite element software,and the monotone static load was applied to the joint to study the mechanical performance of the joint under different pretension.On this basis,the influence of T-stub dimension parameters such as flange thickness,bolt distance and screw hole diameter on the mechanical performance of the joint was studied.The conclusions are as follows:(1)Of high strength bolt and applying the same blind bolt tightening torque,which result in different bolt pretension,the blind bolt tightening torque and strong relation curve,again gives the theoretical formula for calculation of blind bolt pretension of torque coefficient K,and the relationship between blind bolt pretension and sleeve opening Angle curve.(2)Under the action of monotonic static load,for the blind bolt T-stub joint,the tensile bearing capacity of the joint is basically unchanged and the initial stiffness is improved when the pretension of blind bolt is increased under the same size parameters.When the pretension of blind bolt is increased from 26 k N to 100 k N,the initial stiffness of the joint is increased to different degrees.(3)Under monotone static load,the failure mode and tensile bearing capacity of blind bolt T-stub joint under 59 k N blind bolt pretension were analyzed.(4)The mechanical properties of T-stub joints of different sizes under the action of three kinds of pretension are analyzed,and the influence of various size parameters of T-stub joints on the tensile bearing capacity and initial stiffness of blind bolt T-stub joints is obtained.