Lateral Behavior of a Pile Due to Eccentric Horizontal Loads-Paper

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The study examines how eccentric horizontal loading affects the lateral resistance of large-diameter piles, such as wind-turbine monopiles. Because the load acts away from the pile centreline, it induces torsion as well as lateral movement, increasing soil strains and potentially reducing resistance.<br /><br />The authors develop a coupled torsional–lateral elastic strain field for a pile in undrained clay. They use this field with upper-bound analysis and the mobilisable strength design method to estimate limit loads and modify the pile’s nonlinear p-y load-transfer curve.<br /><br />The analysis indicates that eccentricity has little effect on initial lateral stiffness, but it reduces the limit lateral load and causes the p-y curve to reach its limit more quickly as displacement grows. At an eccentricity ratio of 0.275, the limit load falls from 14.53 to 11.42 in normalized terms—about a 21% reduction. The authors also estimate that an eccentricity ratio of 0.2 can reduce reaction forces by around 10%. Beyond 0.275, torsional failure becomes increasingly dominant, making the conventional p-y approach unsuitable.<br /><br />The proposed design chart offers a way to adjust conventional p-y curves for eccentric loading. The authors caution that their model assumes a fully bonded pile–soil interface and should not be applied directly as a practical design solution; actual piles may have lower torsional resistance and experience stronger eccentricity effects.

Keywords

eccentric horizontal loading

lateral resistance

large-diameter piles

wind-turbine monopiles

torsional loading

undrained clay

upper-bound analysis

mobilisable strength design

p-y curve

soil-structure interaction