Finite Element Assessment of Multi-Tierd Eccentrically Braced Frames under Seismic Loading with Shear Link

Multi-tiered eccentrically braced frames (MT-EBF) are a modified version of eccentrically braced frames (EBF), where each story is divided into multiple tiers of braces accompanied by a split link. This system is typically used as a lateral load-resisting system in high-rise structures within a single story. In this study, the behavior of two MT-EBF frames with I-shaped and Box link was evaluated across four intermediate tiers. Since seismic design requirements for this system are not explicitly addressed in any seismic codes, the system was initially assessed in accordance with the AISC 341-22 provisions, similar to the seismic regulations for conventional EBF. This study investigates whether the new structural system can be designed in accordance with the current seismic provisions of the code. The nonlinear behavior of the system was analyzed using the Abaqus finite element software, focusing on the lateraltorsional buckling of intermediate-tier beams and column buckling. The seismic performance evaluation revealed that I-shaped link, connected to the beam via gusset plates, experienced lateral buckling in intermediate-tier beams lacking lateral bracing. In contrast, Box link did not exhibit lateral buckling. However, the first-tier columns under axial compressive forces demonstrated buckling behavior and failed to exhibit stable performance.