Development and optimization of a novel response-amplified friction damper with different friction pairs

In order to improve the efficiency of friction dampers, a shear-type response-amplified friction damper (RAFD) was proposed, which utilized a lever mechanism to amplify the shear displacement and increase the sliding distance of friction pairs. Cyclic loading tests were conducted on 12 RAFD specimens to evaluate the effects of machining processes, friction materials, loading protocols, and bolt pretension on the mechanical performance of the specimens. The results showed that the RAFD specimens with NAO and brass friction pads exhibited plump hysteresis loops, and the bearing capacity, effective stiffness, energy dissipation, and equivalent viscous damping ratio all met the stability requirements of FEMA 356 for the friction damper. Reducing the clearance between pins and holes and strengthening the hole edges shortened the plateau near zero resistances of the hysteresis loops by 75%-90%. Furthermore, combined with rotational analysis of the lever, a design methodology for the RAFD specimen was developed. Based on the response amplification factor R, key mechanical indices such as bearing capacity and equivalent friction coefficient were derived, and a theoretical hysteresis model for the RAFD was constructed, which matched well with experimental results.