Study On Mechanical Properties Of Fully Bolted Box Column-H Beam T-stub Joint

Because of the advantages of light weight,high strength,ductility and seismic performance,steel structures are widely used in building structures.The semi-rigid frame shows strong plastic deformation capacity,good ductility,good energy dissipation and seismic performance.The T-stub semi-rigid joint shows higher bearing capacity and initial stiffness than other forms of semi-rigid joints,and it meets the requirements of "strong joints" in seismic design.Box columns have better cross section characteristics than H-columns due to the non-difference between strong and weak axes.The fullly bolted connection can avoid the brittle failure of the structure caused by weld defects.Therefore,the mechanical properties of fully bolted box column-H steel beam T-stub joints were studied in this research,the main research contents are as follows:（1）27 static models and 22 hysteretic models were built to conduct the parametric analysis for static and hysteretic performances,respectively.A total of 7 parameters（width and thickness of column flange,width and thickness of T-stub flange,thickness of T-stub web,diameter of the bolts and compression ratio of the column）were considered.The impacts of these parameters on the initial stiffness,bearing capacity,ductility,failure mode and energy dissipation properties were analyzed.The results show that width and thickness of column flange,the thickness of T-stub flange and the diameter of the bolts obviously influenced the static and hysteretic performances of the joints,compression ratio only affected the static properties,and other parameters showed little impact on the mechanical properties of the joints.（2）Based on the parametric analysis results,an orthogonal model L₂₅（5⁵）was designed to investigate the influence degree of the 5 main parameters on bearing capacity and ductility.The parameters which contribute to the optimal bearing capacity,ductility and comprehensive performance of the joints were obtained.（3）Adopt the method of simplified analysis and consider a variety of possible failure modes,the joint was divided into several components along the force transfer path.The horizontal capacity of each component was calculated by means of plastic design,the flexural capacity of the joint was determined based on the minimum horizontal bearing capacity of the components.