Experimental study and finite element analysis of a buckling-restrained brace consisting of three steel tubes with slotted holes in the middle tube

• A novel buckling-restrained brace comprising three circular steel tubes with different diameters is proposed.
• Long slotted holes are arranged on the middle tube, and the inner and outer tubes restrain the out-of-plane deformation of the middle tube.
• Cyclic loading tests were conducted to investigate performance of the new buckling-restrained braces.
• A finite element model was established to analyze the influence of the size and number of the slotted holes.
• When the opening-hole ratio is 0.2 and 2 × 2 slotted holes are arranged on the middle tube, the buckling-restrained brace exhibits excellent performance.

A novel buckling-restrained brace comprising three circular steel tubes with different diameters is proposed. The three tubes overlap, and the inner and outer tubes restrain the out-of-plane deformation of the middle tube. Slotted holes are arranged on the middle tube. This BRB has a much larger energy dissipation area and can be conveniently fabricated. The size and number of slotted holes on the middle tube were adopted as test parameters. Five different specimens were tested by using quasi-static cyclic loading schemes to investigate the strength, deformation capacity, hysteretic behavior and failure mode of the new buckling-restrained brace. Nonlinear finite element analyses using ABAQUS were carried out in detail to explain the load-deflection hysteresis curves and modes of failure obtained in all five experiments. According to the tests and finite element analyses results, the structure of the novel buckling-restrained brace is reasonable and effective. When the opening-hole ratio is 0.2 and 2 × 2 slotted holes are arranged on the middle tube, the buckling-restrained brace exhibits excellent performance in terms of its deformation capacity and low-cycle fatigue behavior. The hysteresis curves of the braces are stable and saturated, and correspond to an equivalent ratio of critical viscous damping of 0.40 at the loading amplitude of 1/100L.