ABSTRACT
Buckling-restrained braced frames (BRBFs) for seismic load resistance have been increasingly used in recent years (Sabelli et al. 2003, Uang and Nakashima 2003). A BRBF differs from a conventionally braced frame because a buckling-restrained brace (BRB) yields under both tension and compression without buckling. This study proposes a sandwiched BRB (Fig. 1) that eliminates the use of unbonded material in the manufacturing process and increases the number of design alternatives at both ends of the core plate for gusset connections. Two identical restraining members are formed by welding a steel channel to a flat plate (face plate) and then filled with concrete or mortar. Unlike conventional BRBs that have a steel core inserted into a restraining member, sandwiching a core plate between a pair of restraining members using fully tensioned high-strength A490 bolts expedites the assembly process. Adding additional washers or a thin plate between the side plate and face plate provides a small gap between the core plate and face plate, allowing for expansion of the core plate under compression. The core plate can be examined after earthquakes by removing the bolts and separating the two restraining members in the field. A new core plate can replace a fractured plate and be sandwiched by the original restraining members not damaged during earthquakes. The idea of using a restrained steel
plate for energy dissipation has also been verified for different applications (Chou and Wu 2007, Chou et al. 2008).
