© 2019 Architectural Institute of Japan. All rights reserved. Global out-of-plane stability of buckling-restrained braces is often governed by yielding of the neck. The authors previously proposed a method9) to evaluate this buckling mechanism, including the gusset rotational stiffness, connection length and neck - restrainer flexural continuity. While the proposed method has shown good agreement with experimental and numerical studies, this paper revisits a key assumption in the derivation, where the neck is modelled as an elasto-perfectly plastic hinge. Detailed FEM studies of a chevron BRB experiment with a range of gusset and framing boundary conditions are conducted, and an inelastic buckling model inspired by Shanley’s theory introduced.