Seismic assessment of rocking nonstructural elements: advances, challenges, and future directions

Freestanding nonstructural elements are often governed by rigid motion under seismic actions, and relatively slender elements are likely to be governed by rocking behavior. Rocking behavior can be critical since (a) it could be activated under relatively low intensity actions, (b) it could be associated with relatively large rotation amplitudes and displacements, and (c) it is highly nonlinear and unstable. The study critically reviews the literature and code provisions regarding the seismic assessment of nonstructural elements governed by rocking motion, also accounting for building contents. Theoretical, experimental, numerical, and observational methods and applications are examined to highlight recent advances, current limitations and challenges, and future directions. The motivation stems from the observation that, although several studies have addressed this issue over the past decade, literature remains fragmented, and it lacks coordinated programmatic development strategies. Indeed, the exceptional recent growth in this field underscores the need for a comprehensive synthesis of findings, clearer identification of unresolved issues, and the establishment of consistent research trajectories aimed at enhancing seismic safety and mitigating the risk associated with rocking nonstructural elements. To this end, the present paper identifies critical knowledge gaps and methodological limitations, offering interpretative insights and outlining potential research pathways.