Some Results on the Vulnerability Assessment of HAWTs Subjected to Wind and Seismic Actions

Alberto Avossa,Pasquale Contestabile,Francesco Ricciardelli,Cristoforo Demartino,Diego Vicinanza

doi:10.3390/su9091525

Alberto Avossa, Pasquale Contestabile + Show 3 more

Open Access

https://doi.org/10.3390/su9091525

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Abstract

The spread of the wind energy industry has caused the construction of wind farms in areas prone to high seismic activity. Accordingly, the analysis of wind turbine loading associated with earthquakes is of crucial importance for an accurate assessment of their structural safety. Within this topic, this paper presents some preliminary results of a probabilistic framework intended to be used for the estimation of the probability of failure of Horizontal Axis Wind Turbine-supporting structures when subjected to the wind and seismic actions. In particular, the multi-hazard fragility curves of the wind turbine-supporting structure were calculated using Monte Carlo simulations. A decoupling approach consisting of aerodynamic analysis of the rigid rotor blade model and subsequent linear dynamic Finite Element analyses of the supporting structure, including aerodynamic damping, was used. The failure condition of the tower structure was estimated according to the stress design procedure proposed by EC3 for the buckling limit state assessment. Finally, the vulnerability assessment of HAWTs to wind and seismic actions was evaluated in terms of fragility curves describing the probability of failure of the supporting tower structure as a function of the Peak Ground Acceleration (PGA) for each parked and operational wind condition. In particular, the results highlight a probability of failure larger than 50% for high levels of seismic action (PGA greater than 0.7 g) combined with the rotor in parked condition (wind speed of 3 m/s) or in operational rated condition (wind speed of 11.4 m/s).

Highlights

The seismic response of Horizontal Axis Wind Turbines (HAWTs) has recently attracted growing interest, as the wind energy industry has increased its size, globally
For HAWTs, wind and seismic loads are mainly concentrated at the top of the tower support structure
This paper presents some results on the multi-risk structural response assessment of a 5-MW land-based HAWT subjected to wind and seismic actions, to be used in a probabilistic Sfursatmaineawbiloityrk20. 1F7,i9r,s1t5, 2t5he specifications of the HAWT considered are presented

Summary

Introduction

The seismic response of Horizontal Axis Wind Turbines (HAWTs) has recently attracted growing interest, as the wind energy industry has increased its size, globally. Full system models have been used in conjunction with fully-coupled, nonlinear time-domain simulations capable of accounting for inherent coupling between aerodynamic and seismic response [12] Based on this approach, a complete Finite Element model that accounts for flexibility of the blades in the flapping direction, the bending and twisting flexibility of the tower, and the gyroscopic effects of the rotor has been proposed by Diaz and Suarez [13]. Wind turbine installations have not yet experienced severe ground shaking, given their recent installation in highly seismic regions; the analytical tools for the design seem to be sparse, with more focus on operational aspects than their seismic performance Within this topic, this paper presents some results on the multi-risk structural response assessment of a 5-MW land-based HAWT subjected to wind and seismic actions, to be used in a probabilistic Sfursatmaineawbiloityrk. Further specifications of this HAWT are given in Jonkman et al [19]

Wind and Seismic Actions

Structural Model of the Tower and Aerodynamic Damping

Findings

Aerodynamic and Seismic Response of Wind Turbine