Study On The Semi-rigid Beam-column Joint Under Cyclic Loading Based On Component Method

In the steel structure,as the key part,the joint is easy to appear stress concentration phenomenon,resulting in greater deformation or destruction,affecting the applicability and safety of the structure,so the joint becomes the key research in the steel structure.However,in traditional structural design,beam-column joints are usually divided into rigid or hinge joints to deal with.With the deepening of research,it is generally believed that steel joints have certain rotational stiffness.Therefore,the traditional joint design does not conform to the actual engineering situation.There are three kinds of conventional research methods,namely experimental research,finite element modeling and component method.Compared with the advantages of high efficiency and easy operation and low cost in component method,there are some defects and deficiencies in experimental research and finite element modeling.However,most of the research of component method are confined to the static research section of beam-column joints under monotonic loading.There are two imperfections:(1)The research of component method is limited to the whole joint,the research on the connecting parts,such as bolt-angle steel connection,is less and the research is not deep enough.(2)There are few studies on cyclic loading conditions.Therefore,it is necessary to deepen the study of semi-rigid beam-column joints by using the idea of component method and the research idea of connecting parts-joint.The static bearing capacity and hysteretic behavior of bolt-angle steel connections are studied experimentally and theoretically,and the component method model of semi-rigid beam-column joints is established.First,four sets of bolt-angle connection specimens are designed,the uniaxial tensile and hysteretic behavior of each group were tested,and the mechanical properties of four groups of bolt-angle connections were obtained,including the load displacement curve,loading capacity,deformation capability and failure mode.Hysteresis curve under the test of hysteretic behavior,skeleton curve,ductility coefficient,cumulative hysteretic energy dissipation and stiffness degradation were also included.The experimental results show that: three mechanical parameters such as bolt grade,bolt hole position and angle thickness have great influence on the mechanical properties of the boltangle connection.Both in uniaxial tensile or hysteretic behavior test,it is necessary to consider the improvement of bearing capacity and deformation capacity in the large deformation stage of specimen.On the basis of experiment,considering the different parameters,by analyzing two different stages of small deformation and large deformation,combined with experimental phenomena and existing research results,the mechanical model in tensile and hysteretic of bolt-angle connections are presented,and the correctness of the model is verified by comparing with experimental results.Finally,on the basis of fully studying the mechanical behavior and theoretical models of the bolt-angle connections,by using the idea of component method,the semi-rigid beamcolumn joints(bolt-angle connections in top-and-bottom)are divided into rigid beams and columns,which are connected by two bolt-angle steel connections.The component method model of semi-rigid beam-column joints is established.The correctness of the model is verified by comparing with the existing test results.