| Buckling restrained braced frames(BRBFs)are special concentrically braced frames introduced in structural engineering as lateral loads resisting system due its efficiency and its promise performance under seismic loadings far superior to that of conventional braced frames formerly used in this field.More research conducted on buckling restrained braced frames showed that contrary to conventional braced frames with both limited ductility and low energy dissipation capacity,these bracing types display a stable hysteretic behavior,considerable ductility and large energy dissipation.However,the good structural behavior requires proper design of the BRBF system,of which the collaborative work of the frame and BRBs are the key problem that has not been well studied.The main purpose of this research is to study the buckling restrained braces’ behavior within steel frames in high-rise buildings exposed to seismic loadings and understand the collaborative work of both frames and buckling restrained braces in structures under such loadings.By using this finite element software ANSYS,analysis of a both conventional brace and buckling restrained brace without frame is carried out as well as both bracing within frame and the results obtained are compared to demonstrate how buckling restrained braced frame perform better than conventional braced frame.Moreover,dynamic time-history analysis is conducted on different multi-story buildings with buckling restrained braced frames in order to explore the response of structures with buckling restrained braces under seismic loadings for different stiffness and strength ratio of buckling restrained braces and the frame.From these analysis results,the reasonable range value for the stiffness ratio is obtained as well as the critical design point for the frame.From the critical point of the frame design deduced from analysis,later the practical design method of buckling restrained braced frame is proposed. |
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