Influence of Spacing and Slenderness Ratio of End-Socketed Pile Foundation on Seismic Response of Building Considering Soil-Pile-Structure Interaction: An Experimental Approach

Pile foundations transfer the structural loads from areas with low bearing capacity and stiffness to deeper soil or rocky strata possessing greater bearing capacity and stiffness. The end-fixity conditions, slenderness ratio (length to diameter, or L/D), and spacing (spacing to diameter, S/D) of the piles significantly influence the response of the mid-to-high-rise buildings during any seismic disturbance. The present study aims to investigate the influence of slenderness ratio, spacing, and end-fixity conditions (fixed) of the piles on the seismic response of the buildings through scaled-down model tests. This study uses scaled-down structures with different aspect ratios and pile foundations with varying slenderness ratios and spacing. The super-structure responses are presented in natural frequency, peak spectral acceleration, frequency response, lateral displacement, and interstory drift. The foundation responses are expressed in terms of the rocking, bending moment, and lateral load sharing of the piles. The lateral displacement of the building supported on the pile foundation (L/D=30) has increased by 45.84% for the end-socketed pile foundation compared to fixed-base conditions. It is observed that the interstory drift of the structure supported on a pile (L/D=50) has reduced by 22.19% in comparison to the pile (L/D=30). It is also found that the rocking of the foundation associated with the pile (L/D=50) has reduced in the range of 18.91%-41.39% in comparison to the pile (L/D=30). Similarly, the rocking of the foundation has been reduced by increasing the spacing between the piles from S/D=6 to S/D=3 in the range of 5.75% to 14.93%.