The Mechanical Property Of A New Type Of Buckling Restrained Brace And Its Application In The Frame

This paper introduces the working principle of the BRB and puts forward a new type of buckling-restrained brace whoes core energy dissipation segment is an I-shaped plate with variable cross-section.The new buckling(NBRB)is simulated by the finite element software ABAQUS.This paper analyses the influence of the gap-thickness ration(the ratio of the gap between the core plate to the thickness of the core plate)and the initial imperfection of the core to the bearing capacity of the NBRB,and the hysteretic performance of the NBRB is studied.The new BRB are arranged on the structure according to the lateral stiffness ratio K of the frame to study the behaviors of the steel frame with different stiffness ratio model of buckling restrained braced under rare earthquake,in order to find out the reasonable range of lateral stiffness ratio.The response of NBRB steel frame and BRB steel frame under frequent and rare earthquake are compared and studied.Apply the NBRB to the eccentrically braced frame and do time history analyses under three seismic waves to study the plastic deformation of the NBRB and the link.Through the finite element simulation of NBRB,it is found that the NBRB presented in this paper can go into plastic state earlier than the BRB with the same initial stiffness and there is the phenomenon of continuous yielding.There is the aurora point in the bearing capacity-displacement curve.The gap-thickness ratio has great influence to the bearing capacity of the NBRB,with the increase of the gap-thickness ratio,the aurora point of the bearing capacity-displacement curve become more obvious,and we suggest the gap-thickness ratio should be below 10%.The bearing capacity cures of the NBRB with different initial imperfection are almost the same which means the initial imperfection of the core plate has little influence to the NBRB..Doing time history analysis of 27 NBRB steel frames with different lateral stiffness ratio under three seismic waves,it is found when K is between 0.5 and 2,the layer displacement significantly reduces compared with the pure frame,the shearing force of the basement increases a little,the maximum interlayer displacement angle significantly reduces..The shearing force of the NBRB frame is smaller than that of the BRB frame under frequent earthquake;the shearing force of the NBRB frame is smaller than that of the BRB frame under rare earthquake.The floor displacement of the NBRB frame reduces,which is because the NBRB goes into plastic state earlier and dissipate the energy,and the floor displacement reduces.Through the capacity-displacement curve of the brace in the floor with the largest floor displacement we can find the NBRB is more likely to enter plastic state than the BRB,which can reduce the displacement reaction of the main frame.EBRBF0.75 can realize plastic energy dissipation of both the The NBRB and the energy dissipation section,which possesses double-insurance function under earthquake.EBRBF0.5 is equivalent to the ordinary buckling restrained braced steel frame,and the energy dissipation section is not necessary.