Thesis
Defining the offshore wind monopile structural design envelope
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2023
- Thesis identifier
- T16562
- Person Identifier (Local)
- 201864094
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- Important and compelling questions presently facing the renewable energy industry require an understanding of the upper bound capacity limit of offshore wind turbine (OWT) monopile structures. The areas of interest include, but are not limited to, the following: understanding the influence of modelling techniques on current and future OWT monopile concepts, application of appropriate modelling methods in defining the design envelope, identifying current and future factors limiting how deep offshore wind monopiles structures can be installed and the limit of the installation water depth, the size and weight of the structures according to capacity demand, and installation and operational considerations such as acceptable and excessive pile inclination that may arise from driving larger diameter piles. This research investigated these areas with respect to 5-MW, 10-MW, 15-MW, and 20-MW OWT monopile structures. These were modelled using the application of a 3D finite element to capture the interaction and response of the foundation and structure correctly. The objective was to provide a design tool in the form of an OWT structural design envelope that will serve as an indicative guide for engineering feasibility design and feed into detailed design. This envelope indicated a narrowing of the allowable structural design window because of the complex structural response and behaviour of the new larger and heavier OWT monopiles under operational and 50-year return loading conditions. It clarified the direction of the dynamic response for 5-MW to 20-MW OWT monopiles, considering non-linear soil-structure interactions. The OWT design envelope was defined according to salient design criteria such as the permissible deflection (tilt and rotation), natural frequency/stiffness, buckling, and stresses. The governing design criterion and possible design improvement solutions can be identified from the design envelope. Harmonic response analysis was performed to provide an in-depth understanding of the natural frequency and amplitude response. This was achieved by defining the relative position of the external loads and regions to be avoided with respect to resonance initiation. This research consists of a portfolio of four research areas which have been published in peer-reviewed journal articles. The research areas covered include: 1) A comprehensive literature review and gap analysis considering previous and ongoing studies, with particular focus on offshore wind turbine monopiles. 2) The influence of the soil-structure modelling techniques on the offshore wind monopile structural response where different soil-structure modelling techniques and methodologies are assessed, and the outcome provides direction for improving the engineering design of offshore wind monopile structures and a roadmap for future research developments. 3) Investigating the response of the offshore wind monopile structures under 50-year return loading environmental and operational conditions. 10-MW OWT monopile structure is used as a case study to test the findings and recommendations, from this research on how soil-structure modelling techniques influence the structural response of offshore wind turbine monopiles. 4) The creation and definition of offshore wind monopile structural design envelope for existing 5-MW and 10-MW offshore wind monopile structures and future generation concepts of 15-MW and 20-MW offshore wind monopile structures. Furthermore, the larger and heavier future generation concepts of 15-MW and 20-MW OWT monopile structures are assessed for modelling approaches and understanding of the structural response when subjected to environmental and operational loads.
- Advisor / supervisor
- Brennan, Feargal
- Resource Type
- DOI
Relations
Items
| Thumbnail | Title | Date Uploaded | Visibility | Actions |
|---|---|---|---|---|
|
|
PDF of thesis T16562 | 2023-05-23 | Public | Download |