Experimental investigation of miniature buckling restrained braces for use as structural fuses

• Miniature buckling restrained braces (MBRBs) have full and repeatable hysteretic behavior.
• Stability issues and related design procedures are investigated.
• An experimental program with six MBRB specimens was conducted.
• The MBRBs exhibited cumulative plastic deformations between 181 and 400 times the yield deformation.
• Miniature buckling restrained braces can be useful in a wide range of seismic force resisting systems.

This paper presents the design and experimental investigation of a miniature buckling-restrained brace (MBRB) which can act as a hysteretic damper to dissipate energy when subjected to inelastic axial deformations. The MBRB is similar to a buckling restrained brace (BRB) with a yielding steel core plate restrained from buckling by a grouted restraining tube. The MBRBs, however, are designed to have shorter lengths, smaller steel core dimensions, and smaller yield capacity as compared to a typical BRB. As a result, careful consideration is required for the detailing at the ends and the stability of the MBRB.Small capacity BRBs can be useful in a range of applications as a primary energy dissipating structural fuse or supplementary axial hysteretic damper in seismic force resisting systems. The design, construction, and testing of six MBRB specimens with nominal axial yield forces between 30 kN and 95 kN are reported. Issues related to global stability of the MBRBs are discussed and a stability criterion to prevent global buckling was adopted to design the MBRB end connection pieces. The MBRBs exhibited cumulative plastic deformations between 181 and 400 times the yield deformation and cumulative plastic strain between 46% and 106%. Conclusions about the behavior and recommendations for the design of the MBRB are presented.