Buckling-Restrained Braces are becoming more widely incorporated into seismic designs worldwide.  As their use increases, design engineers should be aware of ways to improve the communication and implementation of BRBs into their projects, as well as the code provisions and requirements for the use of BRBs.

In the June 2025 SEU session, Ben Sitler, PE, Dr.Eng., from Buro Happold, presented Seismic Design with BRBs – Pushing to the Limit.  Ben noted recent changes to the BRB design and testing provisions of AISC 341-16 and 341-22.  Ben explained how BRBs respond in extreme design cases and how to ensure good performance in long and jumbo BRBs, and he reviewed the fundamental behavior of BRBs.

Ben showed how higher-mode buckling and frictional behavior impacts the compressive strains in long BRBs, and how higher strength steel grades may be a valid and even desirable option for large capacity BRBs.  He discussed the need for the design engineer to provide stability bracing for BRBs in the scope of their design.  While the BRB supplier will perform the necessary stability analysis and physical testing as required on a project-specific basis, the design engineer should communicate with the supplier to discuss what connections or bracing may be required to ensure the BRB is torsionally restrained in both directions.  To hear Ben discuss some tips for design engineers providing stability bracing, watch this short video from his presentation:

As Ben discussed, engineers should provide torsional braces and connections on beams framing into BRB connections.  Closed beam sections may also be required where diaphragms are absent.  Maintaining global stability is essential when using BRBs and the design engineer plays a crucial role in ensuring the framing provided can resist these out of plane forces.  Ben also noted that AISC 360 Appendix 6 does provide some guidance on bracing stiffness and strength provisions, however, these were not specifically developed for BRBs and are typically intended for lateral-torsional buckling calculations.  While the torsional forces from BRBs are not usually large, they are still present and need adjacent framing to provide resistance.