Dong-Joon Kim

Investigation of Monotonic and Cyclic Behavior of Tripod Suction Bucket Foundations for Offshore Wind Towers Using Centrifuge Modeling

This paper performed centrifuge load tests of a tripod bucket foundation preliminarily designed as a supporting system of wind turbines and compared the results to those obtained from a test of a monopod bucket foundation. The tripod foundation prototype studied in this study has three bucket caissons, each of which is 6.5 m in diameter and 8.0 m in length. The center-to-center distance between the buckets was 26.9 m. The site is composed of an 11-m thick layer of dense silty sand overlying a thick sandy silt layer. The horizontal load was applied at a height of 33 m from the seabed floor according to the design load condition, and the vertical load was simulated by the self-weight of the model. The moment-rotation angle curves for the tripod foundations were compared with that of the monopod bucket foundation. The moment-rotation curve of the tripod was nearly bilinear, whereas that of the monopod showed a gradual decrease in slope. The yield moment for the tripod foundation was half that of the monopod, but the rotation angle for the yield moment was only 20% that of the monopod. The behavior of the tripod foundation under a cyclic load with respect to the accumulated plastic deformation has also been examined in this study. When the resultant moment of cyclic loading was smaller than the monotonic yield moment, negligible accumulated plastic deformation was observed for both one-way and two-way loading. However, when the resultant moment was higher than the monotonic yield moment, significant cumulated deformation resulted.

Numerical Analysis of Cluster and Monopod Suction Bucket Foundation

Numerical analyses were performed to study the cluster suction bucket foundation performance in comparison with the monopod suction bucket foundation. The possibility of improving the resistance performance of suction bucket foundations by using cluster configuration was studied. Clustered foundations are formed by arranging multiple bucket foundations in relatively short distances among them. A model cluster foundation composed of three individual buckets was configured such that it has the same cross sectional area, length and total bucket weight to a monopod foundation. Results of numerical modeling are presented in the form of load-displacement curves. Vertical, horizontal and horizontal combined with moment load conditions were considered. The results show that the cluster type configuration improved the resistance performance of the foundations under typical loading conditions.Copyright