Experimental tests on shallow foundations of onshore wind turbine towers

Lago, Bruno Dal; Flessati, Luca; Marveggio, Pietro; Martinelli, Paolo; Fraraccio, Giancarlo; Prisco, Claudio di; Prisco, Marco di

doi:10.1002/suco.202100655

Cited by 13 publications

(5 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The model is capable of qualitatively reproduce (Fig. 2) the experimental results of [2] and seems to be a very promising approach for design purposes. In addition, the model can also simply be introduced in structural finite element codes allowing to solve soil-structure interaction problems also accounting the turbine tower.…”

mentioning

confidence: 92%

“…This second aspect can however be neglected, since, in the current practice, very over-conservative approaches are used to design the reinforcements. Recent experimental small scale tests (Figure 1) proved that, even when stirrups are completely removed, exercise loads do not induce the formation of cracks [2]. Therefore, the accumulation of cyclic irreversible rotation is only due to the soil.…”

mentioning

confidence: 97%

See 1 more Smart Citation

A simplified method for calculating the accumulation of irreversible ro-tations of wind turbine shallow foundations

Flessati,

Marveggio

2023

SEG

View full text Add to dashboard Cite

Wind turbines represent a convenient source of renewable energy and their diffusion is a fundamental step for reducing carbon dioxide emissions, main responsible for global warming. Turbine towers are characterized by large heights, therefore the wind load induces considerable bending actions at the base of the structure. Although, especially offshore, deep foundations are usually adopted, shallow foundations are still an option in case of onshore installations [1]. These circular shallow foundations are massive concrete structures (Figure 1) that counteract the bending moment with their own weight. The optimization of the design and the extension of the service life are fundamental from both economic and environmental perspectives. These will increase the competitivity of energy production from renewable wind sources over fossil ones, thus boosting the transition toward sustainable energy. From a geotechnical perspective, the isolated foundations of wind turbines are a peculiar case since the accumulation of vertical settlements and horizontal displacements are not a main concern. On the contrary, the accumulation of excessive rotations due to the wind cyclic loads may reduce the efficiency of the turbine and, in particularly critical cases, define the end of service of the structure. The accumulation of irreversible rotation during the exercise cyclic loads may be induced by both the development of irreversible strain in the soil and the formation of cracks in the concrete foundation. This second aspect can however be neglected, since, in the current practice, very over-conservative approaches are used to design the reinforcements. Recent experimental small scale tests (Figure 1) proved that, even when stirrups are completely removed, exercise loads do not induce the formation of cracks [2]. Therefore, the accumulation of cyclic irreversible rotation is only due to the soil. Recently, numerous constitutive relationships accounting for the cyclic behaviour of the soil were proposed [3,4]. These in principle allow to perform finite element analyses capable of reproducing the soil-structure interaction. However, during the foundation design life a very large number of load cycles (up to 108) is expected, leading to unacceptable computational times. A way to circumvent this problem is the employment of models conceived in the framework of the macroelement approach [5]. This is based on the assumption of reproducing the response of a complex system by using a very small number of degrees of freedom and by introducing an upscaled constitutive law relating generalized stresses (forces and moments) and strains (displacements and rotations). The abrupt reduction in degrees of freedom significantly reduces the computational times. However, the definition of the upscaled constitutive laws and the calibration of its parameters are particularly critical since they will be affected not only by the soil behaviour, but also by the foundation geometry and mechanical properties. In this work, the authors intend to propose a new one-dimensional macroelement to reproduce the moment-rotation response of shallow foundations for wind turbines. This generalized constitutive law, inspired to the one proposed in [6] for reproducing the lateral response of piles, is conceived in the framework of the bounding surface plasticity theory. The main ingredients of this model are a bounding surface and a mixed isotropic-kinematic generalized strain hardening controlling the ratcheting. The model is capable of qualitatively reproduce (Fig. 2) the experimental results of [2] and seems to be a very promising approach for design purposes. In addition, the model can also simply be introduced in structural finite element codes allowing to solve soil-structure interaction problems also accounting the turbine tower. This can be used to adequately reproduce the whole system response and to also optimize the tower design to dynamic loads.

show abstract

mentioning

confidence: 92%

mentioning

confidence: 97%

A simplified method for calculating the accumulation of irreversible ro-tations of wind turbine shallow foundations

Flessati,

Marveggio

2023

SEG

View full text Add to dashboard Cite

show abstract

“…In recent decades, foundation research has focused on the material reduction to save costs and reduce environmental impacts. As a result, progress has been made mainly in the development of tools for design optimization [26] and development of new materials [27]. Moreover, investigations focused on decreasing the carbon footprint [28][29] or analyzing the combined environmental impact of the WTG-foundation [30][31] have been recently conducted.…”

Section: Introductionmentioning

confidence: 99%

Sustainable Design of Onshore Wind Turbine Foundations

Masanet,

Navarro,

Collado

et al. 2024

J. Phys.: Conf. Ser.

View full text Add to dashboard Cite

In recent times, wind power has emerged as a prominent contributor to electricity production. Minimizing the costs and maximizing sustainability of wind energy is required to improve its competitiveness against other non-renewable energy sources. This communication offers a practical approach to assess the sustainability of wind turbine generator foundations from a 3-dimensional holistic point of view. Specifically, the main goal of this study is to analyse the life cycle impacts of one shallow foundation design comparing three different concrete alternatives: conventional concrete, concrete with 66-80% of blast furnace slags and concrete with 20% fly ash, and then to apply a Multi-Criteria Decision-Making model based on TOPSIS method to evaluate and compare the resulting sustainability of each alternative considered. The study results in a methodology for quantifying sustainability rather than simply qualifying it. Therefore, this methodology can be employed for design optimization, such as geometry and materials, with a sustainable perspective in mind. Specifically in this study, concrete with blast furnace slags emerges as the top-ranked sustainable alternative, followed by conventional concrete in second place, and fly ash option in third position.

show abstract

“…Bai [5] investigated the effects of various parameters on the fatigue life characteristics of concrete foundations for wind turbines using parametric studies and numerical simulations. Lago [8] studied the influence of loading methods and treatment on wind turbine foundations using small-scale models. Saito [9] examined the cracking mechanism and anchorage properties of the "single-pole tower" foundation using experimental data and numerical simulations.…”

Section: Introductionmentioning

confidence: 99%

Research on Anchorage Performance of the Foundation Ring for Wind Turbines

Zhang,

Huang,

Zhen

et al. 2024

Materials

View full text Add to dashboard Cite

The foundation ring (FR) is a steel component embedded within the concrete of a wind turbine foundation, playing a pivotal role in connecting the wind turbine tower to the foundation structure. In this paper, the FR–foundation connection is equivalent to the exposed foundation and the shallow foundation by analyzing the anchorage characteristics of the foundation ring. Based on the ABAQUS concrete damaged plasticity model, full-scale modeling of the wind turbine foundation is carried out. The influence of embedment depth, ring radius and base flange width of the foundation ring on moment capacity is simulated. Based on the observed stress distributions under ultimate loads, analytical expressions were proposed to estimate the variation law of anchorage load-bearing capacity in the ultimate load state. Compared with the numerical simulation, the average errors under different influencing factors are 8.2%, 9.6% and 10.8%, respectively. The results indicate that the base flange provided the majority of the moment capacity, though the contribution of the sidewall increased to 25–50% that of the base flange in later stages.

show abstract

Experimental tests on shallow foundations of onshore wind turbine towers

Cited by 13 publications

References 38 publications

A simplified method for calculating the accumulation of irreversible ro-tations of wind turbine shallow foundations

A simplified method for calculating the accumulation of irreversible ro-tations of wind turbine shallow foundations

Sustainable Design of Onshore Wind Turbine Foundations

Research on Anchorage Performance of the Foundation Ring for Wind Turbines

Contact Info

Product

Resources

About