Effect of local buckling core plate restraint in buckling restrained braces

Buckling-Restrained Braces (BRBs) are commonly used as ductile bracing elements in seismic zones. Key limit states governing BRB design include preventing both flexural buckling and local buckling failures. In this study, the authors propose a strategy for the prevention of in-plane local buckling failure of a BRB whose restrainer is composed of a mortar in-filled circular or rectangular steel tube with various mortar thicknesses. Cyclic loading tests on BRBs possessing various mortar restrainers and circular tube thicknesses were carried out to investigate the effect of the mortar and the sectional shape of the restraint tube on the local buckling failure of buckling-restrained braces.

► BRB experiments on the core plate local buckling are carried out.
► The effect of the mortar thickness and the restraint tube shape are focused on.
► The effect of mortar thickness was observed for rectangular restrainer.
► The criteria can be modified by the mortar thickness and the restraint tube shape.
► The revised criteria well explains the ability to local buckling failure in BRBs.