Enhanced Technique for 3D Nonlinear FEM Analysis of Pile Foundation

Abstract

This study aims to resolve the computational difficulties in finite element analysis of pile foundations. Finite element mesh for the analysis of pile foundation includes nonlinear frame elements and three-dimensional soil elements apart from interface elements to represent the soil-pile interaction. Nonlinear FEM analyses with such 3D elements demand more powerful computation environment and takes longer time than linear and two-dimensional analyses. This study explores the possibility of relaxing these computational requirements without compromising the accuracy of the analytical results. First, it is analytically proved that when a nonlinear pile is subjected to lateral displacement, only a portion of pile length closer to the surface is activated. Hence, the total number of elements and the computation time can be substantially reduced if the analysis domain is restricted within the activated length. Next, a mesh condensation scheme is proposed for foundation consisting of large number of piles, and its performance and accuracy is analytically verified. The results showed that the proposed mesh condensation technique significantly enhances the computational efficiency without influencing the results.