Parametric Study on Ductility Capacity of Fixed-Head Piles

Parametric Study on Ductility Capacity of Fixed-Head Piles

This study used SAP2000 to perform a parametric study on the ductility capacity of fixed-head piles. The Winkler-beam model was adopted in which the nonlinearity of the soils and the pile can be considered. The nonlinear secant subgrade reaction coefficientproposed by the Architecture Institute of Japan was followed to consider the soil nonlinearity, and the distributed plastic hin ge model was applied to simulate the pile nonlinearity. In this study, the pile was considered as a limited ductility structure which conditionally allows the pile to enter a plastic state during larger loadings, such as a severe earthquake. The effects of variables, such as the axial force, pile diameter, longitudinal steel amount, and soil stiffness, were investigated in the parametric study. Besides, the over-strength ratio which represents the whole effect of structural property(character) of the pile section was introduced. Results showed that the over-strength ratio significantly influences the ductility of the pile; as the ratio increases, the displacement ductility capacity increases. When the ratio is zero, no displacement ductility can be developed. On the other hand, as the over-strength ratio is fixed, the displacement ductility capacity decreases with the soil stiffness.