Deformation analysis of RC piles and pile groups under combined loading: A nonlinear phenomenological modelling approach

The paper introduces a nonlinear analytical model for deformation analysis of Reinforced Concrete (RC) piles and pile groups subjected to monotonic general planar loading (VHM). The model employs simple analytical expressions for the behaviour of a single pile under: (i) axial compression and tension (V); and (ii) generalized (M−H) lateral loading. The proposed method considers full coupling between the axial and lateral–bending resistance of the piles, the axial load dependency of bending moment capacity and stiffness (cracked and un-cracked) of the RC piles, and the redistribution of bending moments and shear forces along the piles of the group. The method predicts the settlement (w), the lateral displacement (u), and the rotation (θ) of a pile group subjected to any VHM loading combination. The proposed approach offers a practical engineering tool for performance-based assessment of piled foundations, especially at the preliminary design stages. Its key features are outlined, along with a critical discussion of the fundamental simplifying assumptions. The capabilities of the analytical model are verified against rigorous finite element (FE) analysis results.