The Design And Seismic Performance Analysis Of Buckling Restrained Braced Steel Frames

Buckling Restrained Braceds (BRBs) now are new type of energy dissipation components.They can solve the problem that the lateral stiffness of ordinary braces falls suddenly under instability. In the state of tension and compression, the BRBs not only can yield, but also can improve the structure damping which dissipates the seismic energy of the structure under the state of yield. Recently, BRBs are used popularly, which have been used in Japan, the US, Taiwan and China.Firstly, the theory analysis is conducted to the mechanism of BRBs, the restraint stiffness ratio of BRBs, and the gap between the buckling-restraining unit and core segment. And the BRBs with different gaps are analysised by finite element software.Secondly, the BRBFs are designed according to the different rigidity ratios. Nonlinear time history analysis is conducted to10-story plane BRBFs by finite element software AYSYS. And the base shears, top floor accelerations and top floor displacements are compared under different rigidity ratios. The relationships of maximum story drift ratios and the uniformity of maximum story drift ratios with different rigidity ratios are established. At last a reasonable range of rigidity ratio is recommended, which is the reference for the design of BRBFs.Furthermore, nonlinear static analysis is conducted to the BRBFs under reasonable rigidity ratio by finite element software SAP2000. The influence of high-order modes are considered when solving the capacity spectrum curve. And the demand spectrum curves are drawn under different displacement ductilities. Then, the two curves are drawn in the same coordinate system to solve performance point.The response modification factor and the displacement amplification factor of BRBFs are discussed under reasonable rigidity ratio.Finally, to comparing seismic behaviors under the different layout of BRBs, four types of the structure models are designed. The bottom of the shear method, response spectrum method, linear time history analysis, nonlinear time history analysis and pushover analysis are conducted to the structure models, and seismic behaviors under the different layout of BRBs are compared, which are the reference for the design of BRBFs.