A Numerical Study on the Behaviour of Suction Bucket Foundations for Offshore Wind Turbines under Cyclic Loading

Yılmaz, Seyit Alp
Suction bucket foundations simply consist of a cylinder skirt and a top plate, usually made of steel and installed by the assist of suction are a relatively new and economically favorable solution for offshore wind turbines which are exposed to high lateral loads from winds and waves both of which have cyclic characteristic. Understanding the behaviour under the effect of complex cyclic load environment is essential to assess the design requirements of bucket foundations. Deformations and pore pressures may accumulate up to irrecoverable range under cyclic loadings. In this research, a 3D finite element model is developed with ANSYS v.18 software to investigate the behaviour of bucket foundations in sandy soils under cyclic axial compressive and cyclic lateral loads. Hypo plastic constitutive material model with intergranular strain which is appropriate to use with non-cohesive soils is adopted to simulate the material behaviour in cyclic load environment. Special attention was given to the pore pressure accumulation in and around the foundation. A fully coupled two-phase finite element model is adopted in which soil consists of a solid phase, the skeleton, and a fluid phase that fully saturates the skeleton. Coupled pore fluid-structure interaction is solved by the fluid flow by Kozeny-Carman poro-permeability relations and equilibrium conditions. The frictional behavior at the soil-structure interface is modeled by contact elements. The effect of the bucket dimensions, cyclic loading amplitude and frequency, relative density of the soil on the deformation and pore pressure behavior was investigated with a numerical parametric study. A set of design charts are developed according to the findings of the parametric study.


A study on the behaviour of offshore suction bucket foundations under cyclic axial compressive loading
Yilmaz, S. Alp; TAŞAN, HACI ERCAN (2021-10-01)
Suction bucket foundations of offshore wind turbines (OWTs) are subjected to cyclic loads induced by wind and waves. The behaviour of buckets embedded in saturated sandy soil subjected to cyclic axial compression was studied using a finite element (FE) model. Accumulation of permanent soil deformations and excess pore water pressure in saturated sandy soil due to cyclic axial compression were taken into account by a fully coupled two-phase model combined with a hypoplastic constitutive model with intergranu...
A Numerical Study on the Behavior of Offshore Suction Bucket Foundations under Cyclic Lateral Loading
Alp, Yilmaz S.; Ercan, Tasan H. (2020-01-01)
Offshore wind turbines are exposed to high cyclic lateral loads induced by wind and waves which play a special role in the design of foundations. It's essential to clarify the bucket behavior under cyclic lateral loading to fulfil the design requirements of these foundations in both ultimate and serviceability limit states. In this study the behavior of monopods embedded in saturated sandy soil subjected to cyclic lateral loads were investigated using a sophisticated finite element model. The accumulation o...
A Comparative Study on the Performance of a Horizontal Axis Ocean Current Turbine Considering Deflector and Operating Depths
Maldar, Nauman Riyaz; Ng, Cheng Yee; Ean, Lee Woen; Oğuz, Elif; Fitriadhy, Ahmad; Kang, Hooi Siang (MDPI AG, 2020-04-01)
Several different designs and prototypes of ocean current turbines have been tested over recent years. For every design test, emphasis is given to achieving an optimum power output from the flow. In this study, the performance of a Horizontal Axis Ocean Current Turbine (HAOCT) has been investigated using three-dimensional Computational Fluid Dynamics (CFD) simulations for three cases, namely, (1) a turbine without a deflector, (2) a turbine with a deflector, and (3) a turbine with a deflector operating at a...
Effects of installation on the cyclic axial behaviour of suction buckets in sandy soils
Taşan, Hacı Ercan; Yilmaz, S. Alp (Elsevier BV, 2019-10-01)
Suction buckets differ with their easy and cost-efficient installation technique from other foundation types for offshore wind turbines. For successful completion of their installation process, suction is essential, but the imposed seepage leads to the changes in states of the soil in and around the bucket. Especially, a loosening of soil inside the bucket affects the load carrying behaviour of bucket subjected to repetitive loading resulting from environmental conditions. In this study, the behaviour of bu...
Velioglu, Deniz; Tokyay, Nuray; Dincer, Ali Ersin (2015-07-03)
Baffle blocks and sills are common accessory devices which are used in order to stabilize the location of a hydraulic jump and shorten the length of a stilling basin. On the other hand, strip roughness elements which cover the entire length of a basin may be an alternative. The objective of this study is to determine the effects of this type of roughness elements on the characteristics of hydraulic jumps such as conjugate depth ratio, jump length and energy dissipation. The study is carried out using experi...
Citation Formats
S. A. Yılmaz, “A Numerical Study on the Behaviour of Suction Bucket Foundations for Offshore Wind Turbines under Cyclic Loading,” Ph.D. - Doctoral Program, Middle East Technical University, 2021.