Axial capacity of open‑ended steel pipe piles in sand꞉ comparison of analytical methods and FEM modelling

This study investigates the axial capacity of open‑ended steel pipe piles in sand through a combined analytical and numerical approach. A database of 26 field load tests from global offshore and nearshore projects was established to evaluate five design methods꞉ API (2007), GEO (2006), ICP‑05, UWA‑05, and HKU‑12. Comparative analyses show that CPT‑based methods significantly outperform traditional technical standards, with lower prediction scatter and improved consistency in estimating total, base, and shaft capacities. Among these, HKU‑12 achieved the closest agreement with measured capacities, followed by UWA‑05, while API and GEO exhibited large variances due to limited consideration of soil plugging and simplified stress correlations. To complement the analytical evaluation, 3D FEM models were developed in PLAXIS to simulate installation‑induced deformation and soil plugging. The simulations reproduced realistic load–settlement responses and showed that axial capacity is highly sensitive to the prescribed installation displacements. Best‑fit results required much smaller displacement inputs than those suggested in an earlier study, indicating that installation effects for open‑ended piles differ fundamentally from other displacement piles. Overall, the study demonstrates the accuracy of refined CPT‑based methods and presents the potential of FEM modelling in improving the reliability of offshore pile design.