Analytical Study on the Predictability of Controlled Rocking Frame and Podium Systems

ABSTRACT While rocking systems are increasingly researched and developed as a promising approach to achieving seismic resilience, several studies have identified the unpredictability of their dynamic response as an obstacle to their wider adoption. Despite a significant body of literature which has identified and studied the chaotic behaviour of unenhanced rocking frames, other studies have shown that practical applications of controlled rocking systems demonstrate a more predictable response that is similar to that of more conventional yielding systems. This paper examines the differences between these two bodies of work and identifies parameters shown to improve rocking predictability. Subsequently, a perturbation study conducted on a controlled rocking podium system subjected to historic ground motions is employed to study the influence of each parameter on the predictability of such systems. The results reveal that adding supplemental damping, increasing the contribution of the superstructure properties on the rocking system behaviour and limiting the rocking rotation effectively reduce the sensitivity of rocking systems to perturbations in the rocking parameters. In addition, adding auxiliary stiffness was found to be a viable method to improve the stability of these systems but did not significantly enhance predictability.