Seismic Performance of Timber Frames with Timber Buckling-Restrained Braces

The building industry requires the development of a ductile lateral force-resisting system made of mass timber to allow mass timber to continue to grow in popularity as the primary structural building material. A timber frame with mass ply lam (MPL) beams and columns with a timber buckling-restrained brace (TBRB) was subjected to a quasi-static cyclic loading protocol defined according to the qualification procedure of conventional buckling-restrained braces (BRBs). Two of the TBRBs in this study included a carbon fiber-reinforced polymer (CFRP) wrap to help confine the two ends of the mass ply panel (MPP) casing and improve the performance of the brace. The experiments showed that the TBRB without any CFRP wrap met the requirements for qualification of conventional BRBs, and the mass timber braced frame was able to reach a drift ratio of 3.0%. The TBRB with CFRP wraps met the requirements for qualification of conventional BRBs; the confinement provided by the CFRP wraps postponed failure of the TBRB by enabling the steel core to reach a maximum strain of 3.1% in both tension and compression and the mass timber braced frame to reach a maximum drift ratio of 4.5%.