An innovative cyclic loading device to study long term performance of offshore wind turbines

Bhattacharya, Subhamoy; Nikitas, Georgios; Vimalan, Nathan

doi:10.1016/j.soildyn.2015.12.008

Cited by 51 publications

(15 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Also the cyclic lateral loading characteristics described in this paper do not consider wind and wave misalignments, even if they do not often act in the same direction. As a result, this may lead to an overprediction of foundation tilting by the DEM simulations, following the findings by Nikitas et al (2016).…”

Section: 3supporting

confidence: 58%

Distinct-element analysis of an offshore wind turbine monopile under cyclic lateral load

Duan

Cheng

2017

Proceedings of the Institution of Civil Engineers - Geotechnica

View full text Add to dashboard Cite

This paper presents a distinct-element method study of the dynamic behaviour of a rigid bored monopile for an offshore wind turbine foundation subject to force-controlled cyclic lateral loads. A two-dimensional model of a granular assembly was developed using the particle flow code. The model was consolidated under high gravity to simulate existing centrifuge model tests. The simulation results showed great similarity to the published experimental measurements in terms of the relationship between loading and the normalised lateral displacement. The dependency of the accumulated rotation, lateral deflection and stiffness on the two key loading characteristics, loading magnitude and direction, were analysed. Particle-scale information was employed to reveal the micromechanics of these dynamic behaviours. It was seen that relative particle displacement fields provided clear micro-scale evidence of the development of shear zones induced by the lateral cyclic loading of the pile. Meanwhile, local void densification was also observed through particle movements.

show abstract

Section: 3supporting

confidence: 58%

Distinct-element analysis of an offshore wind turbine monopile under cyclic lateral load

Duan

Cheng

2017

Proceedings of the Institution of Civil Engineers - Geotechnica

View full text Add to dashboard Cite

show abstract

“…Based on the discussion above, the soil-structure interaction can be simplified into two superimposed cases, see [19] and is discussed below: (a) Cyclic overturning moments (typical frequency of 0.01Hz) due to lateral loads of the wind acting at the hub. This will be similar to a "fatigue type" problem for the soil and may lead to strain accumulation in the soil giving rise to progressive tilting.…”

Section: Dynamic and Cyclic Soil-structure Interaction In Offshore Wimentioning

confidence: 99%

Predicting long term performance of offshore wind turbines using cyclic simple shear apparatus

Nikitas¹,

Arany²,

Aingaran

et al. 2017

Soil Dynamics and Earthquake Engineering

Self Cite

View full text Add to dashboard Cite

Abstract:Offshore wind turbine (OWT) foundations are subjected to a combination of cyclic and dynamic loading arising from wind, wave, 1P (rotor frequency) and 2P/3P (blade passing frequency) loads. Under cyclic/dynamic loading, most soils change their characteristics. Cyclic behaviour (in terms of change of shear modulus change and accumulation of strain) of a typical silica sand (RedHill 110) was investigated by a series of cyclic simple shear tests. The effects of application of 50,000 cycles of shear loading having different shear strain amplitude, cyclic stress ratio (ratio of shear to vertical stress), and vertical stress were investigated. Test results were reported in terms of change in shear modulus against the number of loading cycles. The results correlated quite well with the observations from scaled model tests of different types of offshore wind turbine foundations and limited field observations. Specifically, the test results showed that; (a) Vertical and permanent strain (accumulated strain) is proportional to shear strain amplitude but inversely proportional to the vertical stress and relative density; (b) Shear modulus increases rapidly in the initial cycles of loading and then the rate of increase diminishes and the shear modulus remains below an asymptote. Discussion is carried out on the use of these results for long term performance prediction of OWT foundations.

show abstract

“…Figure 15a shows the schematic representation of the setup. This is currently the most appropriate physical modelling technique, and details can be found in [31]. Type 3 modelling technique is scalable, can model wind-wave misalignment, can be used in field testing, and can also study fatigue-related issues.…”

Section: Types Of Scaled Model Apparatusmentioning

confidence: 99%

Physical Modelling of Offshore Wind Turbine Foundations for TRL (Technology Readiness Level) Studies

Bhattacharya

Lombardi

Amani

et al. 2021

JMSE

View full text Add to dashboard Cite

Offshore wind turbines are a complex, dynamically sensitive structure due to their irregular mass and stiffness distribution, and complexity of the loading conditions they need to withstand. There are other challenges in particular locations such as typhoons, hurricanes, earthquakes, sea-bed currents, and tsunami. Because offshore wind turbines have stringent Serviceability Limit State (SLS) requirements and need to be installed in variable and often complex ground conditions, their foundation design is challenging. Foundation design must be robust due to the enormous cost of retrofitting in a challenging environment should any problem occur during the design lifetime. Traditionally, engineers use conventional types of foundation systems, such as shallow gravity-based foundations (GBF), suction caissons, or slender piles or monopiles, based on prior experience with designing such foundations for the oil and gas industry. For offshore wind turbines, however, new types of foundations are being considered for which neither prior experience nor guidelines exist. One of the major challenges is to develop a method to de-risk the life cycle of offshore wind turbines in diverse metocean and geological conditions. The paper, therefore, has the following aims: (a) provide an overview of the complexities and the common SLS performance requirements for offshore wind turbine; (b) discuss the use of physical modelling for verification and validation of innovative design concepts, taking into account all possible angles to de-risk the project; and (c) provide examples of applications in scaled model tests.

show abstract

An innovative cyclic loading device to study long term performance of offshore wind turbines

Cited by 51 publications

References 11 publications

Distinct-element analysis of an offshore wind turbine monopile under cyclic lateral load

Distinct-element analysis of an offshore wind turbine monopile under cyclic lateral load

Predicting long term performance of offshore wind turbines using cyclic simple shear apparatus

Physical Modelling of Offshore Wind Turbine Foundations for TRL (Technology Readiness Level) Studies

Contact Info

Product

Resources

About