A novel all-steel buckling restrained brace for seismic drift mitigation of steel frames

Buckling restrained braces (BRBs) as metallic dampers can supply stable and balanced hysteretic response. While BRBs exhibit outstanding energy dissipation capacity, their low post-yield stiffness contributes to large residual drift concentration in simply supported buckling restrained braced frames. The present study introduces a novel all-steel tube-in-tube BRB composed of a short-length hybrid core serially connected to a non-yielding robust member. The hybrid core includes short-length yielding members made up of circular hollow sections surrounded by an all-steel encasing system. High strain hardening capacity of short-length hybrid core enhances the post-yield stiffness, thus reducing the residual drift in simply supported buckling restrained braced frame. In this paper, first the components of proposed brace are represented in detail. Subsequently, the design procedure and stability analysis results are provided. The feasibility of conceptual hybrid BRB is evaluated by finite element analysis method. Afterwards, the global response of prototype buckling restrained braced frames comprising conventional and proposed braces are appraised via pushover and nonlinear time history analyses. The analyses results designated the significant efficiency of proposed braces to help mitigate inter-story and particularly residual drifts in buckling restrained braced frames.