Numerical and Experimental Evaluation of a Simplified Lateral Spring Formulation for Rocking Structures

Abstract

Rocking podium isolation systems have gained significant research interest as a method of limiting seismic demands on superstructures and eliminating residual post‐earthquake drifts through self‐centring behaviour. However, while numerous models of varying complexity, including analytical, phenomenological, and physical formulations, have been proposed, implementing them for the analysis of rocking systems poses significant challenges. Analytical models, though simple and efficient, are difficult to integrate with detailed non‐linear superstructure response. In contrast, detailed numerical models are often computationally expensive due to the large number of elements required and the complex material and geometric non‐linearities they capture. Therefore, this study introduces and validates a novel simplified lateral spring formulation for rocking systems that balances ease of implementation with robust integration into non‐linear structural models, which may be utilized in both open‐source and commercial software. The proposed formulation enables accurate prediction of the distribution of maximum rocking displacement, a key engineering design parameter for rocking isolation systems. Model performance is validated through a planar numerical study against the benchmark Housner piecewise model, as well as through three‐dimensional simulations calibrated to experimental results from rocking‐column, rocking‐frame, and rocking‐podium studies. These investigations demonstrate the reliability of the proposed model while also showing improved motion‐specific predictive consistency relative to unenhanced rocking systems, highlighting the advantages of simplified modelling strategies for practical application to controlled rocking systems.