Finite Element Simulation of Different FailureModes for Buckling-Restrained Braces underCyclic Loading

Conventional concentric braces buckle under compressive loading. To overcome this limitation, the Buckling-Restrained Braces (BRBs) were introduced in the mid 70’s. They typically consist of a low-yield steel core and a restraining mechanism. In order to achieve enhanced understanding of the BRB inelastic behavior and failure mechanisms, comprehensive experimental efforts are typically needed. When such experimental programs are unfeasible or impractical, other investigative means are valuable. The presented paper explores the most common BRB failure modes observed through detailed nonlinear Finite Element Analysis (FEA). The FEA is carried out using the commercial software ABAQUS taking into consideration both material and geometric nonlinearities. The FE model is maliciously verified against experimental tests reported in the literature and good correlation is observed. The verified FE model is further utilized to simulate different failure scenarios for BRBs under reversed loading. It is found that among the different failure modes, necking of the steel core is potentially the most serious. It could trigger significant internal damage to the BRB upon subsequent compressive load reversal leading to failure of the entire brace via global buckling.