Study on the load capacity of prefabricated buckling-restrained braces with ductile steel castings based on singular function

Prefabricated buckling-restrained braces with ductile steel castings were used in the special concentrically braced frames to enable brace yield without buckling and prevent brittle failure of brace joints. This study presents a simplified three-segment calculation model subjected to axial force, based on the failure mode of the bracing system, utilizing singular function to derive formulas for the ultimate capacity of the braces. The accuracy of the computational formula was validated through numerical simulations and experimental findings. The outcomes indicate that the core unit of the brace undergoes third-order buckling deformation under axial force. The ultimate capacity of the braces is observed to increase with the cross-sectional area of the core unit but decrease with the length of the ductile steel castings. The theoretical values of the ultimate bearing capacity of the bracing system closely align with numerical simulations and experimental results, with error margins of 2.9 % to 9.3 % and 3.2 % to 4.6 %, respectively. These findings offer a theoretical foundation for the stability assessment of such brace configurations.