Performance Assessment of Buckling Restrained Braces

In the company paper, the global drift capacity and demands of a 6-story steel office building adopted with buckling restrained braces (BRBs) have been evaluated. This paper evaluates the seismic performance of the building from a local perspective. In detail, the capacity and demands of the BRBs were assessed by test data and response analysis. Then, the level of confidence was computed against the potential of BRB yielding, buckling and fracture failures. The result shows that the BRBs can provide a high level of confidence, ensuring the building to achieve the performance objectives of immediate occupancy and life safety. But in meeting the performance objective of collapse prevention, the confidence level may be far smaller than the 50%-value recommended by FEMA 351. It suggests a necessity of more carefully assessing the seismic vulnerability of braced steel frames, especially for collapse prevention and from a local perspective.