Cyclic Behavior of Bucket Anchor Foundation in Silty Sand under Sustained Pull-Out Loads via Centrifuge Model Tests

In recent, suction anchor foundations have been encouraged as an alternative for supporting offshore wind turbines in the deep sea. The foundation for offshore wind turbine foundation should be designed considering the cyclic forces, which cause an accumulated displacement of the structure and degradation of the stiffness of the ground-foundation system. However, previous researches for suction anchor behaviors have mostly focused on static loads, although the forces applying on the offshore structure are cyclic in the sea. Moreover, since the suction anchors are always subjected to sustained pullout loads combined with cyclic loading due to the buoyancy forces of the structure, evaluating the in-service performance of suction anchor foundations considering cyclic loadings with sustained pullout loads is also required. In this study, the responses of a suction anchor foundation under cyclic loading along with sustained pull-out loads were investigated via centrifuge model tests. Consequently, it was observed that the behavior of the suction anchor are dependent on the sustained pullout loads, as well as the cyclic loading. This study highlights that the ratio of sustained pull-out loads as well as the cyclic load effect must be considered when analyzing design loads to accurately evaluate the bearing resistance of the suction anchor foundation.