Hysteretic behavior of all-steel rectangular BRB members supported by single and double pre-tensioning system

Buckling restrained braces (BRBs) have gained significant prominence as modern energy-dissipating elements, particularly in seismic-prone areas. Tubular cores have typically been preferred over rectangular ones due to their superior in plane and out-of-plane performance. This study introduces an all-steel BRB with an integrated pre-tensioning system to strengthen its out-of-plane stability. A verification study was conducted on two research papers to assess element representation and compare the outcomes, revealing a high degree of consistency between the experimental results and the numerical results. In this study, two pre-tensioning configurations (single and double) were accurately analyzed using 3D Finite Element Analysis (FEA). Additionally, the study explored the influence of different steel grades (St. 37, 44, and 52) and initial pre-tensioning force levels. The research consisted of three phases. The initial phase involved validating prior experimental studies on traditional and pre-tensioned BRBs. The second phase focused on designing the BRB models under examination. In the final phase, the study assessed how various parameters affected the behavior of the proposed BRB under cyclic loading conditions. The results showed that implementing the proposed pre-tensioning system significantly reduced the external restraining plate, by approximately 58% for the single pre-tensioning system and 67% for the double pre-tensioning system. Moreover, higher-grade steel materials increased compressive capacity while maintaining consistent axial displacement. An initial pre-tensioning force of 100 kN emerged as the optimal value for the analyzed models.