Steady-state response of a structure equipped with a tunable high-performance friction damper under harmonic excitations

The response amplified friction damper (RAFD) can serve as a high-performance friction damper or a frictional inerter to reduce the vibration of a structure. Since the RAFD is highly nonlinear, the performance of RAFD under external forces is still affected by the axial stiffness, gap, and stick condition. To obtain the key aspects that determine the performance of RAFD, in this study, a theoretical model considering the axial deformability and gap of the RAFD under harmonic loads is established by the equivalent linearization of the friction behavior. The effectiveness of the RAFD on reducing the vibration and the key parameters that determine the effectiveness are investigated. The results show that the proposed model can accurately estimate the steady-state response amplitude of the structure equipped with the RAFD under harmonic excitations. Besides, axial stiffness is the key parameter that determines the effectiveness of the RAFD. A large axial stiffness, and the corresponding large preload, both help to improve the effectiveness of the RAFD and expand the frequency range of external excitations that make the RAFD slide. The gap can enlarge the peak displacement response of the SDOF system. Further, as it is easy to design a RAFD with large inertial mass, this study proposes a design instance to adjust friction and inertial forces, which can expand the applicability of this device in engineering aspects.