Evolution of the Seismic Response of Monopile-Supported Offshore Wind Turbines of Increasing Size from 5 to 15 MW including Dynamic Soil-Structure Interaction

Cristina Medina,Guillermo M Álamo,Román Quevedo-Reina

doi:10.3390/jmse9111285

Cristina Medina, Guillermo M Álamo + Show 1 more

Open Access

https://doi.org/10.3390/jmse9111285

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Abstract

As a result of wind power’s expansion over the globe, offshore wind turbines (OWTs) are being projected in seismic prone areas. In parallel, the industry develops increasingly larger and more powerful generators. Many of the seismic response analyses of wind turbines conducted so far only consider smaller units. In this paper, a finite element substructuring model in frequency domain is used to compute the seismic response of four reference OWTs from 5 to 15 MW founded on monopiles embedded in several homogeneous soil profiles with shear wave velocities from 100 to 300 m/s and subjected to different accelerograms. The foundation behaviour is obtained through a continuum model including kinematic and inertial interaction. The relevance of soil-structure interaction and main trends of the seismic response of OWTs are inferred from the presented results. Although the seismic maximum bending moments increase with the size of the OWT system, their relevance with respect to the ones produced by design loads decreases as the turbine gets bigger. The same effect is observed for the shear forces if the soil is soft enough. The inclusion of SSI effects almost duplicates the seismic response when compared to the rigid base scenario.

Highlights

During the last decades, the wind energy industry has been evolving in the direction of greater turbines, with longer blades, higher towers, and more powerful generators
This paper aims at studying the relative importance of seismic loads in the design of monopiles for supporting offshore wind turbines (OWTs) depending on their size
The seismic response of the OWT and supporting monopile is computed through a finite element substructuring model in the frequency domain

Summary

Introduction

The wind energy industry has been evolving in the direction of greater turbines, with longer blades, higher towers, and more powerful generators. A large portion of the seismic response analysis of wind turbines that can be found in the literature were conducted on common designs at the time, which size and power were generally much lower than those corresponding to the large wind turbines that are currently being installed or projected for the near future. Their conclusions are not necessarily transferable to present needs. As a consequence of the increasing interest in guidance for the seismic design of wind power plants, a new recommended practice has been recently published [9]

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