DAMAGE-FREE SELF-CENTRING LINK FOR SEISMIC RESILIENT EBFs: EXPERIMENTAL TESTS AND NUMERICAL STUDY

Several innovative seismic-resilient structural systems have been developed and investigated in the last few decades with the main objective of realising low-damage structures able to return to a fully functional condition quickly after a seismic event. Many of such studies focused on developing self-centring systems to enhance structures’ repairability, mainly considering Moment Resisting (MRFs) and Concentrically Braced Frames (CBFs). Conversely, only a few research studies proposed solutions to achieve seismic resilience in Eccentrically Braced Frames (EBFs). The present paper reports the experimental evaluation of a damage-free self-centring device to be employed as an innovative seismic link in EBFs. The device has been recently proposed and numerically investigated by the authors and combines longitudinal post-tensioned bars with disk springs to control the self-centring behaviour and friction devices to provide seismic energy dissipation capacity. Experimental cyclic tests have been carried out according to standardised procedures to validate the self-centring capability and investigate the hysteretic response of the proposed solution. A three-dimensional model developed in ABAQUS has been validated against test results to capture the local behaviour of the device. At the same time, simplified two-dimensional models have been developed in OpenSees to evaluate the global response of a six-storey EBF, conventionally designed according to Eurocode 8 recommendations and successively upgraded with SC-links. The seismic performance of the two structures has been evaluated through Incremental Dynamic Analysis and compared. The experimental tests revealed that the specimen can exhibit a self-centring response and ensure damage-free behaviour. On the other side, the numerical results show that the use of the proposed self-centring link reduces the interstorey drifts, providing the structures’ reparability without needing realignment.