Hysteretic Behavior Study On Web Of Beam-Column Joints In Steel Frame

Steel structure has been widely applied in engineering with the advantages of light weight,flexible layout,good earthquake resistant performance.The earthquake disasters occurred frequently in recent years and it has caused huge property damage and casualties.It becomes more and more important to study the seismic performance of steel structure.The beam-column joints in steel frame is the weak link in seismic.The webs of beam-column joints are usually out of work just because of weak carrying capacity,which will lead to failure of joints and even collapse of the whole structure.This paper shows the equivalent stress nephogram of weds in beam-column joints,bolts,the connecting plates of rigid joints and semi-rigid joints,beam section of joints and hysteretic curves of all kinds of test specimens by Workbench with bilinear kinematic hardening model and yield criteria of Von-Mises.The paper includes two kinds of loading system: monotonic loading and cyclic loading.We can get the different influence of every test specimens according to the computing result of Workbench,so that we can put forward reasonable measures to guide nodes seismic design in engineering practice.There are many contact pairs during the establishment of model,such as,lower surface of nut and connection plate,outside of column flange and connection plates,wall of hole and screw.We use the method of bound to imitate weld line while frictional contact to the others.The model is divided to finite element with manual mode.There are highly concentrated elements in connection angles,connection plates and bolt group.The bottom of the column is completely fixed while the top of the beam is applied vertically downward load and the far-end of beam is applied displacement load.We can get the different influence to webs in joints,connection plates and bolts of rigid and semi-rigid test specimens with different arrangement of inclined stiffener under monotonic loading.At the same time,we also can get hysteretic curves of rigid(RN)and semi-rigid(HRN)test specimens.By analyzing the finite element result,we obtain the following conclusion:both under monotonic loading or cyclic loading,it can greatly improve the mechanical properties of node to arrange inclined stiffener.The node form of RN3(the inclined stiffeners are placed both sides of the web crossing each other.)should be used to rigid joints seismic design.For the semi-rigid joints,the inclined stiffener can reduce the stress of the web of nodes while enlarge the stress of bolts under monotonic loading and the inclined stiffener have little effect on the hysteretic performance,so we should use inclined stiffener according to the actual situation.