Piles in two-layered soils subjected to S-waves: Comparative analysis and simplified analytical solutions

Abstract

The seismic response of piles embedded in layered soils is strongly affected by kinematic demands that arise at soil interfaces with sharp stiffness contrasts. This study compares Euler?Bernoulli and Timoshenko beam formulations within a two-parameter Winkler foundation framework, assessing the influence of soil?pile tangential stresses and shear distortions on pile behavior. Results show that incorporating rotational springs has a significant effect on bending moments and shear forces, while cross-sectional shear distortions play a secondary role. Building on these insights, simplified analytical solutions and design charts are developed to estimate peak bending and shear demands at soil layer interfaces due to kinematic interaction. Validation against three-dimensional finite element analyses and existing analytical models demonstrates strong agreement, confirming the reliability of the proposed approach. The formulations strike a balance between accuracy and simplicity, providing practical guidance for the preliminary seismic design of piles in layered soils.