Experimental validation of Rocking CBFs with Double Acting Ring Springs

Abstract

Double acting ring springs are an energy dissipation device developed for Centralised Rocking Concentrically Braced Frames (CRCBFs). Two configurations have been experimentally tested with both giving good behaviour but the second configuration, known as Type II, exhibiting the better performance, developing stable and repeatable flag-shaped hysteresis loops with considerable energy dissipation and active self-centring. To observe the global behaviour of the CRCBFs, two-thirds scale bottom storey frames with the double acting ring spring type II were tested. Each bottom storey frame comprised a beam, a brace, a concrete filled SHS column with a double acting ring spring at the column base, a central rocking pivot base plate, and a vertical post. The beam and brace were passed through the concrete filled SHS column to achieve rigid connections between those components. A vertical post was provided to support the beam and to maintain the stability of the frame, as only a half part of the braced frame was fabricated. The experimental testing of bottom storey frames has been conducted under slow-speed static cyclic loading and to high-speed dynamic loading. Furthermore, the bottom storey frames have been modelled in SAP2000. The experimental test results showed the behaviour of the double acting ring spring governed the global behaviour of the CRCBFs which developed stable and repeatable flag-shaped hysteresis loops under different loading rates and always dependably self-centred. Additionally, the experimental test results were in accordance with the SAP2000 results.