Nonlinear lateral stiffness and bearing capacity of suction caissons for offshore wind-turbines

The paper investigates the linear-elastic and nonlinear stiffnesses of a suction caisson used as monopod foundation for an Offshore Wind-Turbine (OWT). Starting from caissons at low working stresses, in which case the linear elastic theory provides an adequate engineering model for soil, analytical expressions for the elastic stiffness matrix of a flexible skirted foundation are proposed and validated. To account for the nonlinear foundation response, the paper proposes a simplified equivalent linear iterative approach where the effective foundation stiffness is expressed in terms of deformation amplitude. To this end, utilizing results from a 3D finite element parametric study, non-dimensional charts have been produced for caissons ranging from perfectly rigid to flexible with variable embedment ratios. To deal with uncertainty on the conditions at the soil-skirt interface, three idealized interface scenarios – “fully-bonded”, “tensionless”, “frictionless” – are implemented. Reduced values of foundation stiffness are computed for a frictionless contact. On the contrary, the impact of a “tensionless” interface, whilst trivial in elastic problems, is intensified with progressing soil inelasticity resulting in severely reduced stiffnesses and capacities. Moreover, with increasing relative skirt flexibility, the elastic stiffnesses of deep suction caissons tend to recede substantially, but the rate of stiffness degradation is fairly attenuated.

• Record URL:
  • https://doi.org/10.1016/j.oceaneng.2018.10.020
• Record URL:
  • http://www.sciencedirect.com/science/article/pii/S002980181830800X
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/00298018
• Supplemental Notes:
  • © 2018 Elsevier Ltd. All rights reserved. Abstract reprinted with permission of Elsevier.
• Authors:
  • Gelagoti, F
  • Georgiou, I
  • Kourkoulis, R
  • Gazetas, G
• Publication Date: 2018-12-15

Language

• English

Media Info

• Media Type: Web
• Features: Figures; References; Tables;
• Pagination: pp 445-465
• Serial:
  • Ocean Engineering
  • Volume: 170
  • Issue Number: 0
  • Publisher: Pergamon
  • ISSN: 0029-8018
  • EISSN: 1873-5258
  • Serial URL: http://www.sciencedirect.com/science/journal/00298018

Subject/Index Terms

• TRT Terms: Caissons; Offshore structures; Stiffness; Turbines; Wind power generation
• Subject Areas: Marine Transportation; Terminals and Facilities;

Filing Info

• Accession Number: 01689162
• Record Type: Publication
• Files: TRIS
• Created Date: Dec 20 2018 3:32PM