Experimental Study And Theoretical Analysis Of Buckling Restrained Brace And Steel Frame Joint Under Seismic Action

Buckling-restrained brace(BRB)is a new type of energy dissipation components,there are many advantages for BRB in steel frame,such as light weight,good ductility,lateral force resistance and so on.It has been widely applied in practical engineering.In order to investigate the influence of different connection types on seismic performance,failure modes and working mechanism of connections between BRBs and steel frame,some quasi-static tests were performed on five BRB steel frame joints.Theoretical analysis was conducted based on the experimental results.In addition,finite element(FE)analysis and parameter analysis were completed.The following research work has been carried out:(1)The experimental studies of five specimens BRB-steel frame joints under horizontal low-cyclic loading were conducted,which study parameter is the connection of BRBs and gusset plate.Detail analysis of the P-? hysteresis curves of BRB-steel frame joints with the changing of different parameters to explore seismic performance and failure mode.(2)The experimental results of each specimen were discussed and analyzed.The seismic performance about stiffness degradation,strength degradation,energy dissipation capacity,ductility coefficient were estimated.The working mechanisms of this structure and yield order of all components were analyzed on the basis of rotation deflection and the strain development.(3)Established FEM of BRB-steel frame joints,horizontal load(P)-horizontal displacement(?)curves were recorded and the accuracy of the FEM was verified.The nonlinear full-stage analysis of welded connection or mixed connection(bolt-pin)specimens between BRBs and gusset plates were carried out under monotonic loading.The failure mechanism and the distribution of stress or strain in the joint region were obtained.(4)The simplified calculation model of single-layer single-span steel frames with BRBs were established by software ABAQUS and the accuracy of this model was verified.The effect of some parameters on the structural mechanical behavior and stress distribution were investigated.The parameters includes the yield strength of the gusset,axial compression ratio,gusset plate thickness,the ratio of the vertical distance(L)from the edge of the gusset plate to the stiffener on gusset plate end and the effective width(bE)of the gusset plate(Whitmore),the connection of buckling-restrained braces and gusset,stiffened plate for gusset plate and frame aspect ratio.