Study on the Seismic Performance of the Buckling- Restrained Braced Frames

Considering the fact use of the buckling restrained braced frames (BRBFs) is growing in recent years, behavior of this system against the earthquake forces is needed. These frames are the new type of the concentrically braced frames (CBF) which can absorb more energy than the common concentrically braced frames considering prevention from the bracing buckling. In this article, many BRBF steel frames are selected in stories 6,9,12 and 15 and analyzed and designed according to code AISC-2005. In the next stage, we study seismic performance of the frames in the related hazard level considering the rules of rehabilitation instruction. In this research, some cases such as drifts of stories and performance of BRBF components including beam, column, and bracing. We analyzed and studied accuracy of the drift intensity coefficient presented in AISC code for this system considering results obtained from nonlinear dynamic analyses. The results indicate unsuitable performance of BRBF in DBE. It seems that the displacement intensity coefficient presented in AISC results in non-conservative estimation of the stories displacements. Therefore, in this research, a new value has been proposed for this coefficient