Effective Buckling Length for Buckling Restrained Braces Considering Rotational Stiffness at Restrainer Ends

Buckling Restrained Braces (BRBs) are commonly used as ductile bracing elements in seismic design. A key limit of BRB is overall flexural buckling. However, their effective buckling lengths are affected by the stiffness and strength of their connection zones. In this paper, each connection zone is modeled as two rotational elastic springs at gusset plate and two rotational elasto-plastic springs at the end zone of the restrainer. Their stiffness and strength are investigated by mock-up experiments and analyses, and their evaluation methods are proposed.