<p>This study assessed the side resistance behavior of barrette piles under uplift loading using a database of load tests for drained and undrained soils. Four methods, representing different displacement stages on the load–displacement curve, were employed to estimate the measured side resistance. Traditional α and β methods were used to evaluate the analysis parameters. The back-calculated adhesion factor (α_CIUC) ranged from 0.38 to 1.22, while stress factors (K/K_o) were calibrated at 0.84 for drained soils and 0.83 for undrained soils. Since both the uplift and compression data exhibit a similar range of α_CIUC and undrained shear strength s_u(CIUC) values, the α_CIUC–s_u(CIUC)/p_a relationship was refined considering both loading conditions. Using the measured capacities from the four methods alongside existing analysis parameters of drilled shafts under uplift loading as a basis for predicted capacities, ultimate limit state model factors for calibrating resistance factors in reliability-based design were determined, ranging from 0.59 to 1.50 for drained soils and 0.51 to 1.91 for undrained soils. The L₁ method displayed the lowest mean model factors (bias) of 0.51 to 0.63 and was effective for 2.8–4.2 mm displacement. The slope-tangent and L₂ methods, with bias values of 0.77 to 0.95 and 1.10 to 1.35, respectively, mobilized capacities at 6.9–8.8 mm and 18.1–21.6 mm displacement, respectively. In contrast, the Chin method mobilized capacities at much larger displacements (&gt; 45.5 mm). Notably, the predicted capacities closely aligned with slope-tangent capacities across both soil conditions. Based on the analyses, the α_CIUC and K/K_o values for barrette piles were higher than those of drilled shafts.</p>