Seismic Behavior of Double Activation Self-Centering Brace and Braced Structures

The self-centering technical approach is used widely to improve building resiliency. This paper presents a double activation self-centering brace (DA-SCB) with two groups of disc springs activated successively. Compared with current self-centering braces (SCBs), the DA-SCB is first activated under small displacement excitation to dissipate energy, and reactivated under large displacement excitation, leading to a higher bearing capacity. Cyclic loading tests were conducted on the SCB and the DA-SCB in order to comparatively study their energy dissipation and the self-centering behaviors and to validate the hysteretic performance of the DA-SCB. Moreover, the double flag-shaped model was developed to predict the hysteretic behavior of the DA-SCB. Fifteen-story steel frame models with SCBs (SCBF) and DA-SCBs (DA-SCBF) were analyzed to study the influence of the reactivation behavior on the seismic resilience of these structures. The test results showed that the bearing capacity and the energy dissipation ability of the DA-SCB were highly consistent with those of the SCB within the same design parameters. Comparisons of the prediction and test results indicated that the proposed model can accurately replicate hysteretic responses of the DA-SCB and the SCB. The DA-SCBF and SCBF have equivalent self-centering behavior. However, the seismic performance of the DA-SCBF is higher than that of the SCBF, and the economic loss of the DA-SCBF after earthquakes decreased by 8.08% compared with the SCBF. Moreover, compared with the SCB, the DA-SCB uses fewer disc springs and can attenuate the weak story effect. To sum up, the seismic resilience level of the DA-SCBF first increases and then decreases with an increased gap length.