Development and experimental research on friction - Metal yield composite damper

Dampers are widely utilized for energy dissipation and vibration reduction in building structures. However, traditional dampers often have relatively simple energy dissipation mechanisms, leading to a growing research interest in enhancing their vibration reduction efficiency and adaptability. This paper presents a novel friction-metal yield composite damper, notable for its simple structure. The working principle is detailed as follows: it dissipates energy through friction during small to moderate displacements and through metal yielding during large displacements, thereby providing increased rigidity after friction-induced stiffness reduction. To evaluate its performance, six damper specimens were fabricated, including two pure friction dampers, two metal buckling dampers, and two composite dampers. These specimens underwent low-cycle reciprocating loading tests. The friction coefficient ( μ ) was determined, and the effects of pre-tightening force ( N ) and the width of the short steel tube ( L ) on the mechanical properties of the composite damper were analyzed. The results indicate that, prior to the activation of the anti-slip mechanism, the friction damper exhibits a parallelogram-shaped force-displacement hysteresis curve. When the loading displacement surpasses the anti-slip threshold, the metal buckling damper engages, thereby increasing rigidity. As displacement continues to increase, the damper enters the energy dissipation stage, with the damping force rising and the hysteresis curve adopting a spindle shape, indicative of staged yielding and dual-stage energy dissipation characteristics. Based on the experimental findings, a finite element model was developed to explore the effects of the ratio of radial yield force to friction force of short steel pipes ( F y / F f ) and the ratio of radial yield displacement to design anti-slip displacement of short steel pipes (Δ y /Δ 2 ) on damper performance. The study reveals that when the F y / F f value ranges from 1.1 to 5.6 and the Δ y /Δ 2 value ranges from 1 to 1.7, the composite damper demonstrates optimal performance. This research provides a theoretical foundation and practical guidance for the design and application of this type of composite damper.