Seismic fragility curves for onshore wind turbines including effects of earthquake-induced landslides

Onshore wind turbines are key components of green and sustainable energy infrastructure in many countries, which are built to exploit wind energy and turn it into electricity. To maximize input energy, onshore wind turbines (OWTs) are typically placed in open areas or on the crest of slopes in mountainous regions. Nonetheless, those locations pose the risk of OWTs under geological hazards, such as earthquakes and landslides. This study presents a methodology for development of fragility curves of OWTs located on soil slopes subjected to earthquake-induced landslide hazard, accounting for damage due to slope instability on both underground electric power pipelines and superstructure. Different performance levels are quantitatively defined multiple engineering demand parameters and their thresholds to assess functional and structural damage to OWTs at both local and global spatial scales. To that aim, a detailed finite element model of a benchmark wind turbine developed by the National Renewable Energy Laboratory was developed in OpenSees software. After that a suite of seismic ground motion records was selected, permanent slope displacements were predicted and incremental dynamic analysis of the benchmark OWT was carried out to calculate seismic fragility of both the pipeline and superstructure. Results indicate a strong influence of slope geometry and soil properties on seismic fragility, emphasizing the significant impact of landslides in addition to ground shaking. While previous studies have examined OWT vulnerability to wind and seismic forces, they often treat these hazards separately and overlook their interaction with soil instability. This study highlights the underexplored yet critical role of earthquake-induced landslides in assessing the seismic risk of OWTs.