Experimental study on bamboo-shaped buckling-retrained energy dissipater with different grades of steel

Buckling-restrained energy dissipaters are miniature energy dissipaters that constrain an inner core through an outer tube and have been widely utilized to improve the seismic performance of fabricated structures. Low yield point steel is often used to produce energy dissipaters, but the mechanical behavior of low yield point steel energy dissipater is rarely investigated. In this paper, a quasi-static test of bamboo-shaped energy dissipaters with different grades of steel was carried out. The influence of the material and configuration of the core on the fatigue performance and failure mode was evaluated. Test results showed that all specimens demonstrated stable hysteretic performance. The equivalent viscous damping ratio of low yield point steel energy dissipaters was relatively large at small strain amplitudes. At large strain amplitudes, both had a similar energy dissipation capacity. The compressive strength adjustment factors and strain hardening factors of low yield point steel energy dissipaters were higher because of their lower post-yield stiffness and significant isotropic hardening. The fracture mode on the low yield point steel energy dissipaters was similar to flat rupture, and significant necking was observed here. However, the normal strength steel energy dissipaters exhibited slant fracture, and no evident necking occurred. Two deformation modes were proposed. A calculation method for the buckling wavelength of the energy dissipater was proposed. When the effective length of the yielding region was smaller than the buckling wavelength, the fatigue performance of low yield point steel energy dissipater was better than that of normal strength steel energy dissipater, and the low yield point steel energy dissipater had a better reserve performance.