Study On Seismic Performance And Design Method Of Widen Beam-end Flange Connection Of Box-column To Middle-flange Or Wide-flange H-shape Beam

Since the Northridge earthquake and the Kobe earthquake in Japan,the research and development of beam-to-column connection with high ductility,the plastic rotational ability has become a significant research topic.A joint with widened beam-end flange is a novel connection that can increase the bending capacity at the beam-end by widening the flange and can make a weakened section area at the end of the flank artificially.Meanwhile,the plastic hinge can be formed at a certain distance from the column surface,and then the purpose of making the plastic hinge away from the connection is reached.At present,domestic and foreign scholars have done lots of work on connection with widened beam-end flange for weak-axis of I-section column.Still,research on connection with widened beam-end flange for box-column to H-shape beam is relatively less.This study mainly focuses on the seismic performance of widened beam-end flange of box column to H-shape beams,such as the failure mechanism,hysteretic behavior,mechanical property,and ductility.Using ABAQUS,established a series of finite element models with variable parameters.The nonlinear analysis was performed to determine the critical parameters that influence the connection’s seismic behavior and determine these parameters’reasonable value.Based on the finite element analysis results,a design method for the joint is proposed and verified.The main results are summarized as follows:1.The results of finite element simulation analysis show that:When the widen beam-end flange connection is applied,both the proportion of the right angle side of the widened side plate and direct expanded flange should be controlled between 1:2.5-1:3.5,and the ratio of the length of the reinforced section l_a=（0.55–0.70）b_f,the length of the transition section l_b=（0.33–0.39）h_b,the width of the reinforced section b_wf=（0.15–0.25）b_fthe plastic hinge can be fully developed respectively,which can ensure that the joint has,plastic rotation ability,higher bearing capacity and ductility;The axial compression ratio of the joint with widened beam-end flange should be limited to the standard,otherwise column local buckling instability will occur;The failure pattern of the joint depends mainly on the bending capacity of the beam,the linear stiffness ratio of beam to column should be limited within 1.8;The form of widened beam-end flange has an obvious influence on the seismic performance of the joint,triangle and direct expanded flange can better meet the design requirements and show good seismic performance and practicality.2.As per the three parameters l_a,l_b and b_wf,we applied an experiment on different sections of HM340×250×9×14,HM390×300×10×16,and HW350×350×12×19series.We observe that,on the first two HM340×250×9×14,HW350×350×12×19of l_a and b_wf ductility and plastic rotation are reduced.Whereas,HM390×300×10×16series,both ductility and plastic rotation are increased.3.According to the joint skeleton curve,the mechanical performance indexes of series joints with different wing expansion forms are calculated.It can be seen that the initial rotational stiffness of joints with different types of flaring has little difference when the long and short sides of the beam end flaring are the same.The ductility and the plastic rotation ability of the triangle and directly expanded flange are relatively good.4.This paper put forward a design method that is reasonable and reliable for the widened beam-end flange connection of box-column to H-shape beam.