Hysteretic Behavior Of New Spliced Joints With Cantilever Beams Under Low Cycle Repetition

According to the code,a new type of joint with cantilever beam segment splicing steel frame is designed,which has the characteristics of less bolt consumption and high construction efficiency.Three kinds of beam-to-column connection modes are designed,and one of them is chosen as the basic specimens.On the basis of the basic specimens,the length of cantilever beam segment,the number of high-strength bolts and the thickness of splicing end plate are changed.Three sets of ABAQUS finite element models are established for three parameters respectively,and the hysteretic performance under different parameters is simulated by finite element method.The results show that:(1)under low cycle reciprocating load,the lower flange of cantilever beam is prone to yield due to asymmetric connection between upper and lower joints,and the positive bearing capacity and ductility of the specimen are higher than those of the negative one;(2)by changing the length of cantilever beam,it is found that the longer the cantilever beam section is,the less the influence of asymmetry of the joints is,but the longer the cantilever beam section will reduce the ductility of the joints.It is suggested that the length of cantilever beam segment should be 1.5-1.8 times the beam height;(3)by changing the number of high-strength bolts,it is found that increasing the number of bolts at the splicing flange will increase the bearing capacity of the joints,but reduce the bolts in the splicing zone of the flange will reduce the bearing capacity of the joints,but the ductility will be improved,but changing the number of bolts at the splicing end plate has little effect on the hysteretic behavior of the joints;(4)splicing end plate has little effect on In addition to bearing the shear force of web,the plate also bears a part of the bending moment,and transfers the internal forcethrough extrusion at one end and tension at the other end;(5)After meeting therequirements of the code,the end plate thickness should be made a certain safety reserve,and it is suggested that the end plate thickness should be equal to the beam web thickness.Based on the study of new type joints,three improvement schemes are put forward to improve the premature yielding of lower flange of cantilever beam section.The simulation analysis shows that the three improvement schemes can improve the joint defects,but the way of setting web transverse stiffeners in the splicing zone of cantilever beam section will cause out-of-plane buckling,which is not suitable for use.The simulation results of the other two optimization schemes are also presented.The difference is not big,so we can choose according to the actual project.The bearing capacity and energy dissipation capacity of the improved spliced joints with cantilever beams are obviously improved,but the ductility is lower than that of the traditional spliced joints with cantilever beams.