New equation to determine the load percentage carried by raft in piled raft foundations

Document Type : Research Article


1 Faculty of Engineering- Kharazmi University

2 Faculty of Engineering, Kharazmi University, Tehran, Iran


Piled raft foundations are an effective and economical system in case of high-rise buildings and are a suitable alternative to conventional deep foundations. In this type of foundations, raft is in direct contact with the soil and hence it carries a significant portion of the load. Regarding the design of piled raft foundations, one of the most important issues is to determine the proportion of load carried by the raft. In this paper, numerical analyses using the Finite Element Method (FEM) were carried out by developing 3D finite element models and with considering interaction effects for a piled raft foundation, the effective factors and their impact on load percentage carried by raft, are investigated. In addition, a new equation for determining the load percentage carried by raft in granular soil is proposed for a group less than a 9´9 pile configuration. The developed model is verified with available experimental results. The results of numerical analyses show that the load percentage carried by the raft is significantly affected by several parameters, such as the distance of the piles from each other, the diameter of the piles, the internal friction angle of the soil and the number of piles in the group. In the current study, from the numerical analyses, it has been observed that the percentage of the raft carried load in piled raft system varies from 15% to 42% of the applied load.


Main Subjects

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