Experimental investigation of buckling-restrained braces with glulam-filled steel tube

Most previous studies have intensively explored the use of mortar or concrete as filling materials in the restraining casing of buckling-restrained braces (BRBs), while the characteristics of other fillers remain less explored. This study investigates the novel use of glued-laminated timber (glulam) as a filling material for the square tube in the restrained segment of BRBs as an alternative to mortar or concrete. Six groups of fullscale BRB specimens with a span of 4030 mm were designed and experimentally tested, featuring two types of core material configurations: single-core and double-core, both with the same yielding cross-sectional area, considering the important affecting parameters to evaluate its cyclic behavior. The findings revealed that the proposed BRBs exhibited a typical failure mode, with rupture occurring in the steel core yielding segment near the transition segment's end. Based on the failure cycles, BRB specimens with larger steel core sections significantly prolonged fatigue life compared to the effect of plate thickness in the restraining segment. Specimens with double-core steel demonstrated better performance in maintaining the balance between tension and compression strength than single-core specimens. A reinforcement strategy was recommended for the transition segment to prevent early fractures, allowing the brace to achieve more cycles and effective performance.