Hybrid re-centering viscous dissipaters : spectral analysis and experimental validation

Abstract

Mitigation of the impact of earthquake ground motions on the structures relies to a great extent on the use of supplemental dissipaters. A mechanism capable of repeatable and consistent energy dissipation can potentially lead to reduced structural damage, repair costs, and downtime due to earthquakes. A hybrid dissipater is developed and designed to provide integrated damping and re-centring capabilities. This dissipation device consists of a viscous damper (VD) for its rate-dependent dissipative behaviour and a friction ring-spring (RS) for its re-centring capacity. A nonlinear spectral analysis reveals the overall efficacy of the hybrid device which offers significant reductions in peak and permanent structural drifts that come with an increase in the base shear level. A prototype hybrid device is manufactured and tested to validate the concept. It consists of a viscous device with silicone oil (viscosity = 100 cSt) as the damping fluid and a ring-spring damper with a peak design force of 26 kN. Displacement inputs have an amplitude of 25 mm and frequencies of 0.25- 1.80 Hz and ring-spring preload of 26%. The overall device has a peak response force of 27 kN at input velocities of ~280 mm/s. At this speed, ~20 kN comes from the ring spring and ~7 kN from the viscous damper. These experimental tests are used to delineate the function of the individual components of the device and assess the behaviour of the hybrid combination as a complementary step to the predicted analytical behaviour.