Piled raft systems : a coherent and simplified design approach -

Abstract

Piled rafts are effective and economical foundation systems for towers and superstructures. They have allowed designers to push the bounds of foundation engineering for tall buildings, in addition to providing more economical solutions than standard pile solutions. The piled-raft system is complex due to the substantial interactions between its structural and base soil-rock components. Nevertheless, given the advantages it presents it is important the Structural and Geotechnical Engineers fully understand the behavior of such systems and evolve appropriate design and implementation approaches. Despite the attractive economical features of piled-raft systems and the fact that they have been used for at least two decades, the fundamental understanding based on research in this field is still lagging. This deficiency is clearest in the inconsistency of local and regional design approaches-practices associated with piled rafts. The fact that such designs require collaboration and interaction-input from both Structural and Geotechnical Engineers has contributed to some of the observed-documented inconsistencies. The central objective of the research presented was to investigate the response of piled-raft systems and to understand the relevant interactions between its various constituents through a series of behavioral analyses carried out using finite element software, Plaxis 3D. This step was followed a critical review of local-regional structural design strategies for piled rafts through a broad and in depth collection of information and meetings with local and regional design firms. The current practice was evaluated and recommendations for enhancement were then made-suggested to allow for streamlining and improving the design processes and outcomes. Part of the suggested improvements was based on the adoption-modification of a simplified approach for design that is anchored in the published literature on the interactions within the piled-raft-soil system. The evolved simplified approach was validated-calibrated