Impact of Hybrid Damping Devices on Structural Response Parameters, Including Base Shear and Peak and Residual Drifts
The frictional Ring Spring (RS) is a dissipative spring that is used to provide restoring forces and dissipation in a single device. It thus offers significant re-centring capability when used in structural connections to reduce earthquake induced vibrations and maintain/add to its repositioning ability. Working on the basis of sliding contact between double-taper metal rings, a ring spring offers different loading and unloading stiffness’s, which provides the energy dissipation of the device and gives the structure a measure of re-centring restoring force. This research investigates the effects of augmenting a structure with a hybrid dissipation system using ring springs in conjunction with high force to volume (HF2V) dissipaters. The HF2V damper possesses a high level of damping which boosts the dissipative characteristics of the system while using the RS for re-centring. A nonlinear, single degree of freedom system is used to model the behaviour of a building including nonlinear structural stiffness and yielding, as well as nonlinear device models. A spectral analysis is run using a set of 20 different earthquake records and mean response results are presented as reduction factor spectra over a structural period range of 0.2- 5.0 seconds in 0.1 second increments, for output parameters comprising: drift, residual displacement, and base shear. These spectral analyses are examined over a parametrised range of RS and HF2V device stiffness and capacities, to determine the trade-offs in the balance between dissipation and restoring force using such a hybrid system. The results for the best RS and HF2V combination show promising reductions in peak lateral drifts and minimised residual displacements. Compared to the uncontrolled structure, peak drifts and residual drifts are reduced up to 50% and 80%, respectively. However, these reductions are accompanied by an increase in the base shear values for structural periods above 1.0 seconds. These increases range from 10-100% as the period increases to 5.0 seconds. These reduction factor response spectra presented in the results provide mean probabilities of exceedance over a probabilistically scaled suite and could thus be used in a performance based design framework as a guide to select the proper configuration of hybrid damper device.