Evaluating the influence of stoppers on the low-cycle fatigue properties of high-performance buckling-restrained braces

This paper presents experimental and numerical studies on the effects of stoppers on the low-cycle fatigue performance of the buckling-restrained brace (BRB) to develop the high-performance BRB (HPBRB) used in bridge engineering. The stoppers are used to prevent the buckling–restraining system from slipping off the core brace member. Low-cycle fatigue tests under a constant strain amplitude were performed on four specimens with and without stoppers. The experimental results are further verified using a half model and a whole model of the beam elements for the BRB with and without stoppers, respectively. According to the experimental results, the BRBs with stoppers possess a higher low-cycle fatigue performance than those without stoppers. The cumulative inelastic deformation (CID) of the BRBs with stoppers under 3.5% and 4% strain amplitudes satisfies the CID requirement of the HPBRBs, but the CID of the BRBs without stoppers does not satisfy the CID requirement under the same strain amplitudes. If the proper friction between the core brace and the straining system is considered, two models can accurately simulate the hysteretic behaviour of the BRB, and the whole model reflects the BRB without the stoppers more accurately than the half model.

► BRBs were tested to evaluate influence of stoppers on low-cycle fatigue life.
► Two models are proposed for the BRBs with and without stoppers.
► BRBs with stoppers possess a higher fatigue capacity than BRBs without stoppers.
► Friction coefficient is helpful to simulating hysteretic responses of BRBs.
► Whole model reflects BRBs without stoppers better than half model.