Effects of rocking coefficient and critical contact area ratio on the performance of rocking foundations from centrifuge and shake table experimental results

The major objective of this study is to correlate rocking foundation performance parameters with their capacity parameters and earthquake demand parameters using results obtained from 142 centrifuge and shaking table experiments, which include a variety of soil conditions, foundation geometries, structural models, and types of ground motions. The analysis presented in this paper considers all experimental results together, collectively as big data, through nondimensional parameters to identify hidden relationships among different parameters in a capacity-demand-performance framework. Rocking system performance parameters such as seismic energy dissipation in soil, permanent settlement, peak and permanent rotation, tipping-over stability ratio, self-centering ratio, rocking moment capacity, and acceleration amplification ratio are correlated with rocking system capacity parameters such as critical contact area ratio, rocking coefficient, and slenderness ratio of rocking systems and the earthquake demand parameters such as Arias intensity and peak ground acceleration of earthquake. It is found that energy dissipation and settlement correlate reasonably well with rocking coefficient and Arias intensity of earthquake, while peak rotation and acceleration amplification ratio correlate reasonably well with slenderness ratio, rocking coefficient, and peak ground acceleration of earthquake. Rocking foundations in clayey soils show superior performance in terms of seismic energy dissipation and permanent settlement compared to those in sandy soils, especially for relatively small to medium intensity shakings, and the ability of rocking foundations to de-amplify the earthquake motion increases as the magnitude of shaking increases.