Analysis Methods for the Design of Pile-to-Pile Cap Connections Concerning Plain Pile Embedment

This paper presents an overview of published literature on prestressed concrete and steel (H- and pipe) pile-to-pile cap (PTPC) connections and the results of the detailed finite-element analyses (FEAs) carried out on the PTPC connections. The embedment capacities of PTPC connections obtained using existing analytical models proposed in the literature have been investigated. The results of the existing analytical models and the FEAs demonstrated that proper embedment depth can provide adequate lateral resistance to the applied loads on the foundations, and therefore it is highly important to understand the behavior of such connections' details in order to provide a reliable and economical design. This study focuses on a thorough understanding of the connection design capable of developing adequate pile moment capacity (while remaining essentially rigid) without providing for any special reinforcements by just relying on a simple plain pile embedment depth. The observed predictions based on the existing analytical models and the results from the FEAs showed reasonable agreement with the experimental data. It was observed that the FEA is effective in capturing the global and local behavior of the PTPC connections. Even without a special connection detail, the embedment depths alone can contribute to develop adequate moment capacity for the piles with a value equal to the width of the pile. A value in the range of 1.2-1.5 times the width or diameter of the pile is preferable. However, further experimental investigations are necessary to establish the minimum embedment depth to develop the adequate pile moment capacity of steel PTPC connections. The results from the present study demonstrate that FEA can accurately capture the nonlinear behavior for prestressed PTPC connections and point to the need for further experimental and analytical research on concrete cracking behavior at the steel-concrete interface for steel PTPC connections.