Replaceable Buckling-Restrained Brace Coupling Beams in Core Walls

Over the past two decades, buckling-restrained braces (BRBs) have demonstrated their versatility in various non-traditional seismic applications including non-lifting rocking walls, high-rise outriggers, and mega-frame structures. Another use of BRBs is to substitute traditional diagonally reinforced concrete coupling beams with pairs of crossing BRBs (BRB coupling beams). This would be done because BRB coupling beams provide more predicable seismic performance, simple detailing, and it is feasible to replace these components after a seismic event. A feasibility assessment of BRB coupling beams was completed on the recently completed reinforced concrete corewall structure, the Grand Hyatt San Francisco International Airport Hotel. Structural analysis was performed to assess the performance of the building with BRB coupling beams compared to that of the same building with traditional diagonally reinforced concrete coupling beams. Specifically, the BRBs’ impact on building drift, torsion, and force distribution were examined. From this analysis, realistic demands on the BRBs and their connections were determined, allowing for a study on the detailing associated with these BRB coupling beams, particularly, how they can be detailed to facilitate replacement after a seismic event. By using BRBs arranged in a crossing configuration in lieu of conventional coupling beams, there is potential to control distribution of plasticity and ultimately capacity protect the most critical elements from extensive damage.