Experimental Study And Bearing Capacity Analysis Of T-shaped Connection Joints Under Bending Moments And Prying Forces

Semi-rigid bolted connection has become a popular connection form of steel beam-column joints due to its good bearing capacity,seismic performance and installation.T-shaped connection is a typical unit for tension bolt connection,domestic and foreign scholars have carried out extensive research on T-shaped connection,established the basic theory of T-shaped connection,and explored the influence of prying force on T-shaped connection joints and bolt internal forces.Research usually considers that the bolts are axial tension members,only the prying force is taken into account in the calculation of bolt tension.In fact,the bolts are also subjected to bending moments.In addition,the stiffness of the T-shaped connection backplane is relatively weak,and it should not be studied as an infinite rigid plate.Therefore,this paper will combine the finite element software and experiment to mainly study the bolt mechanical properties of being subjected to the prying force and bending moment when the backplane is of limited rigidity.The symmetric T-shaped connector is the research object,change the bolt diameter,two specimens are designed for testing.Experiments show that as the external load increases,the bending stress of the bolt increases continuously and it can reach to thirty-two percent when yield.The influencing factors of failure mode of T-shaped connector were analyzed by ANSYS software,and the stress performance of bolts was mainly discussed.Analysis shows that bolts are indeed in the tensile-bending state.The changes of length of the outer plate and the screw have minute influence on T-shaped connector bearing capacity and bolt internal forces basically.As the backplane stiffness increases,the bolt axial force decreases and its bending moment increases.The increases of end plate thickness can reduce the internal force of bolt.With the increases of the bolt diameter and the length of the inner plate,the bolt bending moment and axial force increase.The improvement of the bolt preload can increase the bolt bending moment,but it reduces the axial force of bolt.During the tension process of T-stub,the contact forces between the upper and lower plates move toward the edges of the outer flange plates,and it move far away from the center line of the bolts increasingly,the calculation force arm gradually increases.With the increases of the inner plate length and the thickness of the end plate,the calculation force arm increases gradually.With the decrease of bolt diameter and the preload,the calculation force arm increases gradually.However,the change of the length of the screw and the outer plate have little influence on the calculation force arm.According to the above variation rule,the fitting formula of the calculation force arm is obtained by fitting calculation.According to the mechanical characteristics of T-stub,the mechanical model of the T-stub under tension is proposed.Combined with the knowledge of structural mechanics,the revised formula of bolt bending moment is obtained through data fitting.