Research On The Seismic Performance Of Assembly Frame Structure With Buckling Restrained Brace

In seismic design of assembly frame structure, assembly frame system has good ductility and dissipation energy ability, but the structure is too soft and has small lateral rigidity;the conventional assembly frame-bracing systems have big rigidity in elastic,but both the ductility and dissipation ability are not good enough, the braces will be buckled because of compression and the frame will be destroyed when earthquake and wind laods apply to the structures. The buckling restrained brace(BRB) has overcome the disadvantages of the conventional brace which can yeild in both compression and tension but without buckling, and exhibits stable hysteretic behavior. Through analysis and research show that the assembly frame with buckling restrained brace can not only strength rigidity but also improve ductility, the brace is the first to yield under sereve earthquake and the main structure is protected, the seismic performance of the structure will be enhanced.In order to analyse the advantage of seismic performance of assembly frame structure with buckling restrained brace, the performance and design method of buckling restrained brace are firstly introduced, then identified the calculation method of equivalent stiffness of BRB, and make the economical comparison with ordinary steel support. The structure calculation software PKPM was used to ensure the core size of buckling restrained brace in every layer, and then the designing method for buckling restrained brace in steel frame is obtained.Established the finite element model of the structure by using ANSYS software, the modal analysis results comparison was made between the assembly frame structure with buckling restrained brace and he assembly frame structure with conventional steel brace.Finite element software ANSYS is used to carry on the time-history analysis for assembly frame structure、assembly frame structure with buckling restrained brace and assembly frame structure with conventional steel brace. Then make the comparative analysis with base shear、the top floor displacement、story drift and axial force of brace in the first and second floors under frequent、design and rare earthquake of the three kinds of structures. The results show that BRB can provide effective lateral stiffness for assembly type structure, three kinds of structures is basically intact in frequently occurred earthquake; Under the design earthquake the BRB began to play its role in energy dissipation mechanism, reducing the base shear of the structure; Underthe rare earthquake the BRB play a full role in energy dissipation mechanism, the seismic performance indices of BRB structure are better than ordinary steel support structure, the story drift is reduced by 25.4%, besides the top floor displacement、base shear of the former are better than the latter.Finally, different types of buckling restrained brace frame models are designed, the designed model’s elasto-plastic calculation is made under the rare earthquake, so that we can discuss their influence of seismic performance and found that reasonable layout of braces can improve lateral rigidity and control lateral displacement., and suggested that the equal area core material should be reasonably scattered layout, at the same time,the BRB should continuous layout in the adjacent span.