Seismic Response of Pile Group Foundations Under Multi-Story Buildings in Sandy Soil: Shaking Table Investigation

The present study aims to examine the effects of the number of stories on the dynamic behavior of pile group foundations in multi-story buildings.Experimental tests were conducted using a shaking table on a small-scale building model with 4, 6, 8, and 10 stories.These models were designed and fabricated with a consistent weight and a scale ratio of 1:20.The multi-story buildings rest on 33 pile groups with an L/D ratio of 16, and are situated within sandy soil exhibiting a relative density of 70%.The shaking table simulated the effects of the Kobe earthquake with a peak acceleration value of 0.82g.The results showed that the vertical displacement (both peak and residual) increases significantly as the number of stories increases.Specifically, when the number of stories increases from 4 to 6, the peak displacement increases by a factor of 3. As the number of stories is increased further to 8 and 10, the peak displacement increases by a factor of 1.9 and 5, respectively.In terms of residual displacement, increasing the number of stories from 4 to 6, 8, and 10 results in an increase by a factor of 17, 5.5, and 33, respectively.These results suggest that even though the weight is constant across all buildings, increasing the number of stories leads to greater building height and flexibility, resulting in increased seismic displacement.Therefore, it is imperative that pile groups are designed to accommodate this augmented movement to maintain foundational stability and ensure structural safety.