Abstract
This paper presents a simplified method for the nonlinear analysis of composite piled raft foundation, CPRF, subjected to vertical loads. As a cost-effective alternative to piled rafts, the CPRF is used with weak soils for low-rise to medium-rise buildings. The raft is analyzed by the FE formulation for a thin rectangular plate. The granular layer is idealized as an incompressible shear layer. The weak soil, short piles and long piles are expressed as soft, semi-stiff and stiff nonlinear springs. The interaction between springs is taken into account by a shear parameter based on the Vlasov model and the interaction between long piles springs is also considered. Compared with the results of the 3D FEA available in the literature for a varied number of problems, the present method provides reasonable results and, thus, represents a significant improvement in the prediction of the CPRF behavior. A parametric study is carried out to investigate the effect of various parameters, i.e., number of long and short piles, area ratio of short piles, stiffness of short piles, and stiffness of granular layer, on the behavior of the CPRF. The findings of this study could be helpful for achieving economical design for the CPRF.