Cyclic tests of glulam frames with buckling restrained braces

Abstract

In this study, an attempt was made to integrate BRBs to glulam frames to provide strength, stiffness, ductility and energy dissipation. Two 8 m wide, 3.6 m high full-scale BRB glulam frame (BRBGF) specimens were designed using capacity design approach and tested under cyclic loading. The BRBs were designed as ductile elements in the hybrid system to dissipate energy under seismic loading and connections and glulam members were designed to remain elastic. The BRBs were connected to the glulam frames by pins and steel gusset plates. Dowelled connections were used in one specimen to connect the glulam members while screwed connections were used in the other. The dowelled connections used Φ12 mm dowels and two 20 mm thick inserted steel plates; the screwed connections used Φ11x300 mm inclined self-tapping screws and two 12 mm thick steel side plates. Both specimens were tested to 1.5% drift ratio. The tests showed that specimens carried high lateral load and achieved a minimum ductility factor of 3.0 according to EN 12512. The connections were well protected with limited damage and negligible moment resisting capacity. Both connections were able to engage the BRBs efficiently and resist the anticipated inelastic demand. The integration of BRBs into glulam frames improved the load carrying capacity, ductility and energy dissipation compared to conventionally timber brace frame (TBF).