Hybrid Soil–Structure Interaction Effects on Rocking Systems with Supplemental Inertial and Soil-Based Damping

Freestanding and rocking structural systems have long demonstrated remarkable seismic performance owing to their inherent rocking working principle such as self-centering capability and damage-avoidance behavior. In recent years, rocking-based isolation concepts have gained increasing attention in earthquake engineering as low-damage alternatives to conventional fixed-base systems. However, their seismic response remains strongly influenced by soil–structure interaction (SSI), impact phenomena, and near-fault ground motion characteristics, which can significantly affect stability and residual displacements.

This study aimed at exploring the potential role of hybrid soil–structure interaction mechanisms in altering the dynamic response of rocking systems. In particular, the combined influence of supplemental inertial effects and engineered soil layers, such as gravel–rubber mixture (GRM) foundations, is investigated from a conceptual and numerical perspective. These components are expected to alter the effective stiffness, damping, and energy dissipation characteristics of the soil–foundation–structure system, especially under pulse-type ground motions.

A simplified modeling framework is considered, in which rocking kinematics are coupled with soil compliance and additional inertial effects. Parametric numerical simulations are performed to investigate key response quantities, including uplift behavior, re-centering tendencies, and sensitivity to ground motion features and soil properties. The role of SSI in controlling rocking stability and modifying seismic demand is discussed.

The results provide insight into how hybrid soil and inerter-based mechanisms may enhance the seismic performance of rocking systems and highlight key parameters governing their effectiveness. The study aims to support future developments in performance-based design strategies for structures prone to rocking and soil-informed seismic isolation concepts, with potential relevance to both modern applications and the protection of freestanding structural systems.