Research On The Seismic Performance Of Self-Centering Buckling-Restrained Brace With Spring And Braced Frame

Although the traditional earthquake-resistant structural system can ensure the safety of people in the earthquake,it has to dissipate the seismic energy through the damage of structural components.Although the buckling-constrained braced frame(BRBF)can dissipate seismic energy through large inelastic deformation of the steel core,it will produce large residual lateral displacement after the earthquake,which will cause great difficulty in repairing and economic loss.Therefore,it has always been a hot issue to provide sufficient self-centering capability for the BRBF.However,most of the existing self-centering systems use metal memory alloys and organic composite ribs,which are expensive to produce and have average stability.In this paper,a new type of self-centering buckling restrained brace(SC-BRB)with springs is proposed and numerical simulation is carried out.The main research contents are as follows:(1)This paper proposes a new type of SC-BRB and states the structure of its self-resetting system.The mechanical properties of the self-centering system,the BRB and the SC-BRB are theoretically deduced,and the preliminary design method of the SC-BRB is given.Three key design parameters that determine the self-centering configuration are found: self-centering(SC)ratio,the number of DISC springs and brace axial capacity.(2)In this paper,the Open Sees modeling method of self-centering buckling-restrained brace is proposed,and a refined model is established using the finite element software ABAQUS.The accuracy of this modeling method is verified by comparing the numerical analysis results of the two models.The Open Sees numerical model of the new SC-BRB is established,and three key parameters are conducted parameters analysis.It is found that the self-replacement ratio is the most important factor affecting the performance of self-replacement support.Based on the analysis results,the recommended range of SC ratio of SC-BRB is given.(3)The numerical model of BRBF and the self-resetting buckling-constrained braced frame(SC-BRBF)were established.Static pushover analyses and nonlinear dynamic time-history analyses were performed on the finite element software Open Sees to investigate the seismic performance of SC-BRB.The drift response of the frame model was obtained under the action of the earthquake at these two risk levels,which are design based earthquake(DBE)and the maximum considered earthquake(MCE).The effect of the SC ratio of the brace on the seismic response of the frame system is compared and analyzed,and it is found that the SC-BRB can effectively reduce the residual lateral displacement of the frame to a negligible range.And the author put forward a reasonable self-reset ratio recommended range for Prototype frame.(4)A probabilistic seismic demand assessment method was used to evaluate the residual drift demand of a SC-BRBF with a SC ratio of 0.5 to verify the rationality of the range of SC ratio proposed before.The study found that the self-reset buckling restrained brace with a self-reset ratio of 0.5 also meets the demand for residual drift under the DBE.