A macro-element model for multidirectional cyclic lateral loading of monopiles in clay

Page, Ana M.; Grimstad, Gustav; Eiksund, Gudmund; Jostad, Hans Petter

doi:10.1016/j.compgeo.2018.11.007

Cited by 29 publications

(11 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The model has been demonstrated to give good agreement with results from finite element analyses of the soil and monopile, results from large-scale pile tests, and results from full-scale field measurements of an OWT installed in the North Sea. [6][7][8] In addition, the macroelement model provides different stiffness after load reversal, as observed in pile tests. 9 The REDWIN model provides an accurate representation of the foundation stiffness and hysteretic damping, which are important for accurately estimating fatigue.…”

Section: Redwin Macroelementmentioning

confidence: 96%

“…REDWIN model 2 was used, which is a single macroelement approach that includes an elastoplastic model with kinematic hardening formulated within the multisurface plasticity framework. 6 It reduces the foundation and surrounding soil to a set of linear and nonlinear load-displacement relationships in the six DOFs of the interface point (the seabed), separating the foundation and the rest of the structure (see Figure 1). It can represent the nonlinear hysteretic load-displacement response observed in experimental tests and in the field, including the coupled response between horizontal loads and bending moments.…”

Section: Redwin Macroelementmentioning

confidence: 99%

See 1 more Smart Citation

OC6 Phase II: Integration and verification of a new soil–structure interaction model for offshore wind design

et al. 2021

View full text Add to dashboard Cite

This paper provides a summary of the work done within the OC6 Phase II project, which was focused on the implementation and verification of an advanced soil-structure interaction model for offshore wind system design and analysis. The soil-structure interaction model comes from the REDWIN project and uses an elastoplastic, macroelement model with kinematic hardening, which captures the stiffness and damping characteristics of offshore wind foundations more accurately than more traditional and simplified soil-structure interaction modeling approaches.Participants in the OC6 project integrated this macroelement capability to coupled aero-hydro-servo-elastic offshore wind turbine modeling tools and verified the implementation by comparing simulation results across the modeling tools for an example monopile design. The simulation results were also compared to more traditional soil-structure interaction modeling approaches like apparent fixity, coupled springs, and distributed springs models. The macroelement approach resulted in smaller overall loading in the system due to both shifts in the system frequencies and increased energy dissipation. No validation work was performed, but the macroelement approach has shown increased accuracy within the REDWIN project, resulting in decreased uncertainty in the design. For the monopile design investigated here, that implies a less conservative and thus more cost-effective offshore wind design.

show abstract

Section: Redwin Macroelementmentioning

confidence: 96%

Section: Redwin Macroelementmentioning

confidence: 99%

OC6 Phase II: Integration and verification of a new soil–structure interaction model for offshore wind design

et al. 2021

View full text Add to dashboard Cite

show abstract

“…OWTs in integrated time-domain analyses. [54][55][56] The basic features and limitations of the model are presented by Page et al 55 The macroelement model used in this study accounts for the change of the foundation stiffness due to nonlinear hysteretic soil behaviour, and as a consequence reproduces hysteretic damping. The model also accounts for the effect of multi-directional loading, which has been found…”

Section: Foundation Modelmentioning

confidence: 99%

“…to affect the foundation stiffness and hysteretic damping. 56 The model is calibrated to results of full 3D continuum modelling of the soil volume and the foundation by FEA. Even though the model have been calibrated to an idealized clay profile the results are equally valid for monopiles installed in sand.…”

Section: Foundation Modelmentioning

confidence: 99%

Fatigue design sensitivities of large monopile offshore wind turbines

et al. 2022

Self Cite

View full text Add to dashboard Cite

The input for fatigue analyses of offshore wind turbines is typically chosen based on design values provided by design standards. While this provides a straightforward design methodology, the contribution of different input parameters to the uncertainty in the fatigue damage estimates is usually unknown. This knowledge is important to have when improving current designs and methodologies, and the parameters governing the uncertainty is typically found through a sensitivity analysis. Several sensitivity studies have been performed for monopile‐based offshore wind turbines, typically focusing on specific turbines and engineering disciplines. This paper performs a sensitivity study for three monopile‐based offshore wind turbines (5 MW, 10 MW, 15 MW) using parameters from several engineering disciplines. The results show that the fatigue utilization is primarily governed by the uncertainty in the SN curves and fatigue capacity. Following this, the uncertainty in the environmental conditions is the dominating uncertainty, with wind loads becoming increasingly important as turbine size increases. Additionally, the effect of modelling uncertainties is investigated. The wind‐related model uncertainties dominate in the tower top, while uncertainties in the wave and soil models dominate in the tower base and monopile. Designers wanting to reduce the uncertainty in a design are recommended to focus on the environmental conditions, and using as accurate models as possible. All modelling uncertainties are significant, but research should particularly be focused on wave directionality and soil models.

show abstract

“…This aspect is very important to the development of equivalent models, for which equivalent stress levels will be targeted in the soil; the application of equivalent loads at the mudline level, instead of on top of the structure, might yield to different distributions for the lateral stresses throughout the pile in the different models. The possible oscillations in the radial orientation of this horizontal load (like the case reported in [31]) are neglected in this case, following the approach adopted by most existing FE simulations [6,7,15,32,33], and therefore, the problem is symmetric, and the symmetry plane is aligned with the applied horizontal load, as schematized in Figure 1. It is worth pointing out here that this 3D hollow model has been extensively validated against experiments, which demonstrates its goodness and validity [34][35][36].…”

Section: Geometry Of the Modelsmentioning

confidence: 99%

Simplified Numerical Models to Simulate Hollow Monopile Wind Turbine Foundations

López‐Querol

Spyridis

Moreta

et al. 2020

JMSE

View full text Add to dashboard Cite

The majority of wind turbine foundations consist of hollow monopiles inserted in the soil, requiring high computational effort to be numerically simulated. Alternative simplified models are very often employed instead. Three-dimensional solid models, in which the hollow structure and pile are substituted by solid cylinders with equivalent properties, are the most extended simplifications. Very few 2D models can be found in the literature due to the challenge of finding suitable equivalent properties and loads to fully represent the 3D nature of the problem. So far, very limited attention has been devoted to the accuracy of both 3D and 2D simplified models under dynamic and even static actions. Thus, in this paper, simplified 3D and 2D solid models are proposed and justified. An elasto-plastic constitutive model with accumulative degradation is used to simulate the soil behaviour, and frictional contact elements are implemented between the soil and pile to model their interaction. These simplified approaches are compared with the full 3D hollow model, under static and cyclic loads. The results demonstrate that the proposed simplified approaches are a reasonable alternative to the 3D hollow model, which allows researchers and designers to drastically reduce the computational effort in the simulations under long term conditions.

show abstract

A macro-element model for multidirectional cyclic lateral loading of monopiles in clay

Cited by 29 publications

References 37 publications

OC6 Phase II: Integration and verification of a new soil–structure interaction model for offshore wind design

OC6 Phase II: Integration and verification of a new soil–structure interaction model for offshore wind design

Fatigue design sensitivities of large monopile offshore wind turbines

Simplified Numerical Models to Simulate Hollow Monopile Wind Turbine Foundations

Contact Info

Product

Resources

About