Shaking Table Tests of a Full‐Scale First‐Story Rocking Isolation System in ROBUST Project

ABSTRACT To enhance seismic resilience of steel structures, this study proposes an innovative First‐Story Rocking Isolation System (FSRIS) and evaluates its dynamic performance through shaking table testing. Developed as part of the “RObust BUilding SysTem (ROBUST)” project, the FSRIS is designed to confine structural nonlinearity to the first story while protecting upper stories. Low‐damage rocking joints are implemented at upper and lower ends of the first‐story rocking columns, while the joints in the upper stories remain rigid. The test structure integrated two rocking isolation frames equipped with replaceable energy dissipation (ED) devices at the column ends, coupled with one gravity frame featuring simple shear connections. Under frequently occurring earthquakes (FOE), the FSRIS behave as a moment‐resisting frame. Beyond FOE intensity, the first‐story rocking mechanism is activated. The FSRIS was subjected to eight seismic excitations, with peak ground accelerations ranging from 0.055 g–0.62 g. White noise was employed to evaluate dynamic properties of the tested FSRIS before and after each excitation. Throughout the test sequence, the system exhibited exceptional self‐centering capability with negligible residual drifts and no visible damage. These findings validate the feasibility of the first‐story rocking concept within current design practices, offering a novel and effective low‐damage solution for the next generation of resilient structures.