Numerical Modeling of Pile Response in Soft Clay under Multidirectional and Cyclic Loading for Floating Wind Turbines

Abstract

Floating wind turbines offer a competitive advantage for harvesting renewable energy, particularly in locations with abundant wind resources. Among the critical components of these systems anchoring and mooring systems are required to secure the wind turbines in place. Pile anchors belong to the anchoring solutions currently available for floating wind turbines. Consequently, this study focuses on the behavior of pile anchors installed in soft clay subjected to cyclic loading, including multidirectional forces. To investigate this, a numerical model was developed using OpenSees and calibrated based on existing centrifuge test data. The results demonstrate that combined average and cyclic loads induce the most significant accumulation of permanent pile displacements when compared with two-way cyclic loading. Conversely, load reversals can contribute to a reduction of these displacements. Notably, the study highlights the effectiveness of multidirectional loading in promoting a more balanced distribution of forces on the pile head. This potentially leads to a more uniform utilization of the pile's overall strength capacity, a desirable feature for resisting the complex loading scenarios experienced by floating offshore wind turbines.