Efficient Beam–Column Finite-Element Method for Stability Design of Slender Single Pile in Soft Ground Mediums

Abstract

Slender single piles are extensively used but susceptible to buckling when embedded in soft ground mediums. Owing to the complexity of soil properties, the soil-structure interaction (SSI) response is sometimes very complicated, but its consideration is essential in the design of slender piles. Current design practice relies on either empirical-based linear analysis approaches or sophisticated finite-element methods, which are overconservative or time-consuming, respectively. Therefore, this paper derives a new Euler-Bernoulli element by adopting Winkler-type continuous springs along the element length for considering SSI responses, eliminating the need to model the ground mediums. Consequentially, this method is numerically very efficient, being suitable for the practical analyses of large-scale structures with the explicit modeling of upper structures and piles. A Newton-Raphson incremental-iterative numerical procedure is developed for determining the equilibrium conditions, where the tangent stiffness matrix and the secant relations are formulated using the Gauss-Legendre method for solving the summation procedures. For allowing large deflections, the kinematic motions described by the updated Lagrangian (UL) method are proposed, where the equilibrium conditions are established by referring the last known configurations. Finally, several benchmark examples are provided for validating the accuracy of the proposed method.