Design Regulations of Buckling‐Restrained Braces with Steel Encasement

Abstract Buckling‐restrained braced frames (BRBFs) can be used as lateral load‐resisting system in high seismic regions. BRBFs are composed of columns, beams, and BRBs. These structural members form a truss system through simple connections to each other and resist horizontal loads due to their axial rigidity. A typical BRB consists of a core plate, debonding material and an encasement. Concrete or mortar filled‐tube is generally used as the encasement mechanism of the BRB but steel encasement alone has also been alternative solution in recent years in terms of easy fabrication and cost saving. Although many studies in the literature focus on the design of BRBs with filled‐tube encasements, research on the design of BRBs with steel encasement is still limited. This study presents design regulations of the BRB with steel encasement which consists of a bolted connection of two separate welded steel components that are symmetrical to each other. The bolts are subjected to tensile forces due to out‐of‐plane deformation of the core plate and shear forces due to inplane deformation of the core plate under compression loads. Determining of the loads acting on the encasement from the core plate, required flexural stiffness of the encasement along with base plate and necessary bolted connection detail are the fundamentals of the study. The design regulations proposed in this study were validated through finite element analysis using ABAQUS software program. This study indicates that design of BRBs with steel encasement is controlled by the axial capacity of the brace.