Displacement Ductility Capacity of Fixed-Head Piles

This study performs a parametric study on the displacement ductility capacity of a fixed-head pile. The Winkler-beam model is employed, in which both the soil nonlinearity and pile nonlinearity are adequately considered. In this parametric study, the pile is regarded as a limited ductility structure which conditionally allows the pile deformation to enter the plastic range during loadings. The analysis variables include the axial force, the pile diameter, the longitudinal reinforcement ratio, and the soil stiffness. The relationships of the displacement ductility capacity of the pile to the curvature ductility capacity and to the over-strength ratio of the pile section are examined through a large number of pushover analyses. Results show that the axial force level, the pile diameter, and the steel ratio remarkably influence the displacement ductility capacity of a fixed-head pile. Their influence can be represented mainly by the over-strength ratio of the pile section. Besides, the influence of the soil stiffness is insignificant: the displacement ductility capacity slightly decreases with the soil stiffness.