Spectral Analysis and Experimental Validation of a Low-Damage Hybrid Dissipater

Abstract

Supplemental dissipation plays a vital role in reducing structural damage, repair costs, and downtime due to earthquakes. A hybrid dissipation mechanism has been developed to offer repeatable and consistent energy dissipation, while maintaining significant re-centring capability. This dissipation device consists of a viscous damper (VD) and a friction ring-spring (RS) combining rate-dependent dissipative behaviour of the viscous device with rate-independent dissipation and re-centring from the ring-spring. This approach, ensures simultaneous displacement reduction and increased self-centring potential. Spectral analysis of a single-degree-of-freedom structure has been carried out to outline the efficacy of the device and delineate the impact and contribution of each component to the overall device behaviour. A prototype hybrid device is tested comprising a viscous damper with silicone fluid and a ring-spring with peak design force of 26kN. These components are connected in a parallel configuration through a fixed outer shell and a moving coupled shaft. Experimental proof-of-concept testing for the hybrid device and single ring-spring includes sinusoidal displacement inputs with amplitude of 25 and 30 mm, loading frequencies of [0.25-1.75] Hz, and ring-spring pre-load of 21 and 34%. The overall device has a peak response force of 32kN at input velocities of ~200 mm/s. At this speed, ~20kN comes from the ring spring and ~12kN from the viscous damper. Further tests on the single viscous device are conducted using silicone oils with viscosities of 100, 500, and 1000 cSt and peak input velocities of [50-300] mm/s to evaluate the impact of viscosity on the damping force. These experimental tests are used to delineate the function of the individual components of the device and assess the behaviour of the hybrid combination, in comparison to the predicted analytical behaviour.