## 2 Background  
SCBF structures built after the incorporation of the Uniform Building Code [17] are designed for a ductile response using a capacity-based design method. However, limited knowledge of the performance of its components and their interaction leads to early strength loss. The premature loss of strength of the brace in the particular story accumulates the inelasticity in that story and forms the soft-story mechanism, which finally leads to the structure's collapse [18]. Hence, the structures need to be designed to avoid premature fracture and to maximize the lateral drift capacity of the brace. [PERSON] et al. [19] first introduced the concept of a tapered gusset plate with linear clearance of twice the thickness of the hinge plate for the restraint-free rotation, which led to the out-of-plane buckling (OOPB) brace system. It was observed that forming hinges on the gusset plate enhances the ductility of the braced frame system. To further improve the performance of the SCBF system, a series of experimental and numerical studies were conducted in the United States, which led to development of a compact rectangular gusset plate arrangement with elliptical clearance [13; 20; 21]. Research also highlighted the influence of the flexibility of the connection on the ductility of the braced frame system but mostly focused on the OOPB brace system. This also illustrates the balance design procedure that leads to the desired yield hierarchy for the SCBF structures [22]. [PERSON] et al. [22] investigated the behavior of the gusset plate connections in multi-story X-braced frames and observed that the seismic performance of the braced frame is affected by the design and detailing of the gusset plates.  
The connection of the CBF system is observed to be the most critical component that not only dissipates the forces to other members of the structure but also helps enhance the system's performance and ductility. However, most of the research in the past two decades has focused on the design and detailing of the OOPB braced system to avoid premature failure and to have the desired yield hierarchy. Recently developed IPB braced systems designed for in-plane buckling have attracted industry and researchers as good, efficient alternative connections for increasing the resilience of the braced frame system. Past experimental research on the full structure of the OOPB system has shown that the brace member's out-of-plane deflection can go up to 500-700 mm before the final fracture. The large deflection may lead to potential damage to the surrounding cladding, non-structure components, partition, etc. It also has the potential to increase falling debris, which is the most prominent cause of mortality in earthquakes. The recently developed flexible design framework aims to reduce earthquake forces on the non-structural components [23], which in fact needs the brace members to buckle in the plane of the system. Mostly, the out-of-plane buckling starts at a lower inter-story drift, and it can go up to 700 mm; severe non-structural damage can occur. For the CBF system, buckling usually starts at a very low drift of about 0.3% to 0.5% [24]. It is expected that in the design-based earthquake (DBE), most of the brace members will show out-of-plane displacement, which will increase the chance of falling debris.