Elastic and Inelastic Behavior of Precast Concrete Piles and Cast-in-Shell Steel Piles in Reinforced Concrete Caps

Understanding the level of fixity and ductility provided by pile to pile-cap connections is essential for the design of piles subjected to lateral loading. In this study, a series of elastic and inelastic finite-element models were developed to replicate the behaviors of both prestressed and cast-in-shell steel piles. The goal of this study was to reproduce the elastic and inelastic load-displacement behaviors observed and recorded in prior, experimental push-over tests. Understanding appropriate modeling techniques for estimating ductility, capacity, concrete-crushing behavior, and plastic-hinge location was the focus of the research. Elastic behaviors (i.e., load, displacement, and corresponding stiffness) were captured accurately in the analytical models for both the cast-in-shell and prestressed piles. Inelastic loads and displacements were closely reproduced for the prestressed piles using a nonlinear stress-strain relationship that was based on confined concrete. The steel pile models reproduced general nonlinear shape behavior but overestimated inelastic stiffness. The research demonstrates accurate nonlinear modeling for prestressed pile connections but points to the need for further analytical research on concrete-cracking behavior at the steel-to-concrete juncture for cast-in-shell steel piles.