Influence of isolated footing embedment on the seismic performance of building considering the soil-foundation-structure interaction: An experimental approach

The present study investigates the influence of embedment depth of isolated footing supporting moment-resisting frame buildings through scaled-down tests. These experiments utilize scaled models representing different building aspect ratios and footing embedment depths. All the model tests are subjected to scaled-down input ground motions of different intensities and magnitudes. These model tests are performed in laminar shear containers through shake table testing. The results obtained for different cases of soil-foundation-structure systems and fixed-base conditions are expressed in terms of natural frequency, peak spectral acceleration, frequency response, lateral deformation, inter-storey drifts, and rocking of the foundation. The analysis reveals that the natural frequency of the coupled system on isolated footings diminishes by 27.52%-58.26% relative to fixed-base conditions, underscoring the significance of accounting for soil-foundation-structure interaction effects. Moreover, a notable increase of 53.6% in the natural frequency of the coupled system is observed as the embedment depth of the footing increases from 0.75 to 6. Additionally, the study demonstrates that the inter-storey drift of the 5-storey building remains well within acceptable limits under dense soil conditions. Consequently, within the parameter range explored in this research, the study concludes that soil-foundation-structure interaction effects are insignificant for low-rise buildings (H ≤ 15 m) supported on isolated footings during seismic events.