Abstract: Buckling-restrained braces (BRBs) have recently become popular in the United States for use as primary
members of seismic lateral-force-resisting systems. A BRB is a steel brace that does not buckle in compression but instead
yields in both tension and compression. Although design guidelines for BRB applications have been developed, systematic
procedures for assessing performance and quantifying reliability are still needed. This paper presents an analytical framework
for assessing buckling-restrained braced frame (BRBF) reliability when subjected to seismic loads. This framework
effi ciently quantifies the risk of BRB failure due to low-cycle fatigue fracture of the BRB core. The procedure includes a
series of components that: (1) quantify BRB demand in terms of BRB core deformation histories generated through stochastic
dynamic analyses; (2) quantify the limit-state of a BRB in terms of its remaining cumulative plastic ductility capacity based
on an experimental database; and (3) evaluate the probability of BRB failure, given the quantified demand and capacity,
through structural reliability analyses. Parametric studies were conducted to investigate the effects of the seismic load,
and characteristics of the BRB and BRBF on the probability of brace failure. In addition, fragility curves (i.e., conditional
probabilities of brace failure given ground shaking intensity parameters) were created by the proposed framework. While the
framework presented in this paper is applied to the assessment of BRBFs, the modular nature of the framework components
allows for application to other structural components and systems.

Keywords: risk and reliability analysis; buckling-restrained brace; stochastic dynamic analysis; fi rst-order reliability
method; cumulative plastic ductility capacity
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