Influence of gusset plate design on the collapse risk of buckling-restrained braced frame buildings
DOI:
https://doi.org/10.5459/bnzsee.1766Abstract
This study examines the impact of gusset plate design on the collapse risk of two buckling-restrained braced frame (BRBF) buildings, incorporating superX and diagonal brace configurations. Nonlinear dynamic analysis shows that the gusset plate axial compressive strength is, on average, 30% lower than the design strength estimated by NZS-3404, indicating that the current design approach may be non-conservative. This study explores three alternative design methods: (i) NZS-3404 design with modifications (NZS-3404-revised), (ii) Court-Patience (CP) method, and (iii) Notional load yield line (NLYL) method. On average, the gusset plate axial compressive strength obtained from dynamic analysis aligns closely with the design strengths predicted by the NZS-3404-revised and CP methods. The NLYL method explicitly accounts for the reduced strength of mid-span gusset plates in super-X and chevron-configured BRBFs. The gusset plate strengths from dynamic analysis are approximately 30% greater than those estimated by the NLYL method, demonstrating that this approach is sufficiently conservative and therefore recommended for design. Within the limited range of brace and gusset plate configurations studied, the collapse risk is reduced by a factor of 3.5 when the NLYL method is used instead of the NZS-3404 method.
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