Analytical Model for Ductility Assessment of Fixed-Head Concrete Piles

Abstract

Under seismic loading, restraint provided by the anchorage of the pile reinforcement in the pile-cap of a foundation may induce a large curvature demand in the pile. For performance-based design of the foundation, the severity of local damage in the pile may be controlled by limiting the curvature ductility demand in the potential plastic hinge region of the pile. The curvature ductility demand depends on the strength and stiffness of the soil-pile system, as well as the equivalent plastic hinge length of the pile. In this paper, a kinematic model relating the displacement ductility factor to the local curvature ductility demand is proposed. The analytical model, which is amenable for a wide range of pile and soil properties, is useful for the design of fixed-head piles. The versatility of the model is illustrated using a numerical example of a reinforced concrete pile embedded in two soil types currently classified in building codes.