7. Summery and conclusions
In this paper a new passive earthquake damper, the Bar-Fuse Damper (BFD), was presented and evaluated both experimentally and numerically. The performance of the BFD was assessed with more than 30 monotonic and cyclic experiments, and the applied bars successfully performed their function as energy absorbers and fuses in all the specimens. The proposed device showed appropriate ductility, energy absorption and stable hysteretic behaviour under cyclic loads without any sudden strength and stiffness degradation. The performance of the BFD depends highly on the nut arrangements of the bars. The simplest design, two nuts on the both ends of the threaded bar, gave a reliable behaviour to the proposed device, as well as the possibility of convenient placing and replacing the bars when they were failed. This proper replacement capability can be considered as a key feature of the proposed device over to other available metallic dampers.
All the applied steel bars as fuses in the proposed device sustained more than 20 loading cycles with cumulative displacement of over 600 mm in the quasi-static cyclic tests along with an average on strength degradation about 10.6% at target displacements of the last six steps. This achieved by taking the maximum BFD displacement equal to 13% of the bar length. In general, the BFD was able to furnish an equivalent viscous damping ratio in the range of 35–65%. Due to the combined flexural-tensile mechanism of the device, the ultimate strength of the BFD was greater than the corresponding yield strength by a factor of more than 6, which enhances the capacity of energy dissipation. On average, the unit weight of the employed steel bars sustained 75 kN force and dissipated 10.5 kJ input energy.
