Seismic design of buckling-restrained braced frames based on a modified energy-balance concept

The conventional energy-based seismic design procedure based on the energy-balance concept was revised for performance-based design of buckling-restrained braced frames. The errors associated with the energy-balance concept were identified and were corrected by implementing proper correction factors. The design process began with the computation of the input energy from a response spectrum. Then the plastic energy computed based on the modified energy-balance concept was distributed to each story and the cross-sectional area of each brace was computed in such a way that all the plastic energy was dissipated by the brace. The proposed procedure was applied to the design of three-, six-, and eight-story steel frames with buckling-restrained braces for three different performance targets. According to the time-history analysis results, the mean values of the top story displacements of the model structures, designed in accordance with the proposed procedure, corresponded well with the given target displacements.