Abstract

In this study, the seismic soil-structure interaction (SSI) of wind turbine support structures is investigated using response spectrum method (RSM) based on the complex eigenmodes. Seismic loadings on wind turbine support structures are newly derived by complex mode superposition RSM. To improve the prediction accuracy of the shear force acting on footings, this method is augmented by introducing the upper limit of modal damping ratios of 10 %. In addition, the bending moment at the hub height due to the mass moment of inertia of rotor and nacelle assembly is considered as an additional loading. The proposed method is validated by comparison with time history analysis (THA) accounting for different types of foundations and different tower geometries. Seismic loadings acting on the towers and footings by the proposed method show favourable agreement with the mean results by THA of several input acceleration time histories, while the original complex mode superposition RSM strongly underestimates shear forces acting on footings.

Highlights

  • In recent years, the expansion in wind energy has increased the construction of wind turbines in seismically active regions, including Japan, and damages on wind turbine support structures caused by huge earthquakes have been reported

  • 205 The proposed method is demonstrated upon numerical examples accounting for different types of foundations and different tower geometries

  • The non-classically damped seismic soil-structure interaction (SSI) model of wind turbine support structures is constructed, and its seismic loadings are analytically derived from 335 complex mode superposition response spectrum method (RSM)

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Summary

Introduction

The expansion in wind energy has increased the construction of wind turbines in seismically active regions, including Japan, and damages on wind turbine support structures caused by huge earthquakes have been reported. The aim of this study is to further investigate the applicability of complex mode superposition RSM to wind turbine support structures, where highly damped modes are dominant in their seismic responses, and to propose an accurate and efficient method to estimate seismic loadings acting on towers and footings.

Seismic SSI model for wind turbine support structures
Input acceleration response spectrum
Augmented complex superposition RSM
Structural damping of steel towers and additional loadings
Numerical verification and discussion
Problem statements
Findings
Conclusion
Full Text
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