Cyclic Loading Test of Phase Change Material (PCM)-Infilled Buckling-Restrained Brace

Buckling restrained braces (BRBs) enhance energy dissipation and ductility considerably by preventing the buckling of steel braces under cyclic loads during earthquakes and, thus, the strength degradation caused by buckling. This paper introduces and discusses the development of BRBs made with an elastomer known as phase change material (PCM), which has superior ductility and faster-filling properties than commonly used mortar while being approximately 50% lighter. BRBs filled with PCM have high ductility and good energy dissipation. To verify the seismic performance of the PCM BRB, axial brace tests and subframe tests were conducted. Using PCM as the filler in the axial tests ensured a stable tension and compression ratio (below 1.5), as recommended by the AISC provisions, and the core material fully withstood axial loads for six cycles beyond 1.5delta_bm. Global buckling occurred after 2.0delta_bm under compression, at which point the experiment was terminated.