Effect of loading eccentricity on the ultimate lateral resistance of tripod piles in clay

In this paper, the ultimate soil resistance of tripod rigid pile foundation subjected to eccentric lateral loads was explored, using the finite-element limit analysis coupled with lower bound, upper bound and 15-node mixed Gauss element formulations. The effect of loading eccentricity on the average pile capacity factor N_p was examined as an emphasis. Two distinct failure mechanisms were identified associated with small and large eccentricity. This study also discussed the influence of different pile group geometries and soil–pile adhesion strengths on the bearing capacity and developed a set of design charts. Finally, a reduction factor G_N, which quantifies the effect of eccentricity, was introduced, and its variations with eccentricity for various pile spacings (s) and soil–pile adhesion factors (α) were additionally presented.