Efficient Pile Distribution for Piled-Raft Foundations for Tall Buildings

The pile foundations are structural units that transfer the superstructure loads to deep levels where a satisfactory supporting ground or sound formation are encountered. It is quite common to have a group of piles supporting a heavy concentrated load. These groups are designed to support all exerted forces. Piles subjected to lateral loads or pull out forces due to wind or expansive soils need to be checked for stability and adequate strength. The pile settlement is a significant factor that needs to be kept within a small differential range. The work presented in this paper was conducted for a tall building proposed for construction at site underlain by limestone formation. It was aimed at comparing uniform distribution of piles under a thick raft and a rectangular tube-like distribution in which piles are concentrated under exterior shear walls. The structure also included two central columns supported by pile groups. Resistance to different loading conditions including vertical, lateral, and pull-out forces were studied and compared for the two pile configurations. The efficient pile distribution was selected. Comments on the efficient system and the choice criterion are given.