Cyclic behavior and damage assessment of all-steel buckling-restrained braces with round-hole tubular steel cores

Buckling-restrained braces (BRBs) are widely used as seismic energy dissipation devices due to their stable hysteretic behavior. Nevertheless, conventional BRBs often exhibit high yield forces, inefficient utilization of casing capacity, and large force demands on connections, limiting their structural economy. This study numerically investigates an innovative all-steel BRB configuration employing a circularly perforated tubular steel core to address these limitations. Three-dimensional nonlinear finite element models are developed in ABAQUS and subjected to cyclic displacement-controlled loading. The numerical framework is validated against published BRB studies. A systematic parametric investigation is conducted to evaluate the influence of perforation geometry, casing properties, gap size, contact conditions, and initial imperfections on cyclic response. The results demonstrate that appropriately designed round-hole tubular steel cores lead to a 20–40% reduction in yield strength, enabling earlier activation of energy dissipation and reduced force demand on surrounding structural components. Stable and symmetric hysteretic behavior without global buckling is achieved. Significant improvements in cumulative inelastic deformation capacity are observed, reaching approximately 15% in the base configuration and up to 130% in the optimized model. In addition, the results show that when perforation parameters are properly optimized, damage accumulation is reduced and ULCF-related performance indicators are improved compared to perforated configurations employing non-optimized parameter combinations. The proposed system provides a promising alternative for high-performance seismic bracing systems.