Bolted ring flanges in offshore-wind support structures - in-situ validation of load-transfer behaviour

2021 ◽  
Vol 176 ◽  
pp. 106361
Author(s):  
Wout Weijtjens ◽  
Andre Stang ◽  
Christof Devriendt ◽  
Peter Schaumann
Author(s):  
Fani M. Gelagoti ◽  
Rallis S. Kourkoulis ◽  
Irene A. Georgiou ◽  
Spyros A. Karamanos

This paper explores the performance of a 10 MW offshore wind turbine (OWT) supported either on a large diameter monopile or a 4-legged jacket emphasizing on the nonlinear response of its belowseabed foundation. The seabed foundation alternatives, a monopile and a multipod foundation, are compared under monotonic, cyclic, and seismic loading. For all nonseismic scenarios considered, the monopile is more flexible than the jacket and transmits higher rotations at the OWT base. The differences between the two alternatives are amplified in the case of nonsymmetric cyclic loading; the monopile not only deforms more than the jacket but tends to accumulate irrecoverable rotation with increasing loading cycles. The seismic performance of the alternative support structures is assessed for a comprehensive set of earthquake motions. It is concluded that both systems are seismically robust especially when subjected to pure earthquake loading, neglecting the simultaneous action of wind and waves. Alarming issues for OWT performance may arise when a nonzero steady wind force is superimposed to the kinematically induced stressing of the seabed foundation due to the seismic wave action. Jacket legs settle unevenly, while monopiles are building up rotations at increasing rates. Assuming a design-level earthquake and a wind thrust of the order 60% of the NC wind loading amplitude, this seismically induced residual rotation for the monopile may often exceed the deformation tolerance criterion. For the same loading combination, the corresponding rotation of the Jacket installation remains safely within the prescribed limits.


Wind Energy ◽  
2016 ◽  
Vol 20 (4) ◽  
pp. 731-747 ◽  
Author(s):  
R. Damiani ◽  
A. Ning ◽  
B. Maples ◽  
A. Smith ◽  
K. Dykes

Energies ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 5195
Author(s):  
Pim van der Male ◽  
Marco Vergassola ◽  
Karel van Dalen

To meet the political goals regarding renewable energy production, offshore wind keeps expanding to waters with larger depths and harsher conditions, while the turbine size continues to grow and ever-larger foundation structures are required. This development can only be successful if further cuts in the levelized cost of energy are established. Regarding the design of the foundation structures, a particular challenge in this respect relates to the reduction of the total computational time required for the design. For both practical and commercial reasons, the decoupled modelling of offshore wind support structures finds a common application, especially during the preliminary design stage. This modelling approach aims at capturing the relevant characteristics of the different environment-structure interactions, while reducing the complexity as much as possible. This paper presents a comprehensive review of the state-of-the-art modelling approaches of environmental interactions with offshore wind support structures. In this respect, the primary focus is on the monopile foundation, as this concept is expected to remain the prominent solution in the years to come. Current challenges in the field are identified, considering as well the engineering practice and the insights obtained from code comparison studies and experimental validations. It is concluded that the decoupled analysis provides valuable modelling perspectives, in particular for the preliminary design stage. In the further development of the different modelling strategies, however, the trade-off with computational costs should always be kept in mind.


Author(s):  
N. Hlaing ◽  
P.G. Morato ◽  
P. Rigo ◽  
P. Amirafshari ◽  
A. Kolios ◽  
...  

2018 ◽  
Vol 6 (2) ◽  
pp. 101-106 ◽  
Author(s):  
Erfan Asnaashari ◽  
Andy Morris ◽  
Ian Andrew ◽  
Wolfgang Hahn ◽  
Jyoti K. Sinha

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