PSI - Issue 64

Serdar Soyoz et al. / Procedia Structural Integrity 64 (2024) 484–491 Soyoz et al. / Structural Integrity Procedia 00 (2024) 000 – 000

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5. Conclusion In this study, long-term and vibration-based monitoring of a 900-kW onshore wind turbine in Istanbul, Turkey was performed. Seismic fragility curves were developed by updated FEM and considering different levels of wind speed. Local buckling stress values were determined by pushover analyses. The band range of change in modal parameters based on environmental and operational conditions was presented. It was shown that when all effects were removed frequencies showed less variability. Finite element model including piles and soil springs of the turbine was updated; results indicate that there is significant change in soil spring coefficient. Fragility curves show that spectral accelerations leading 50% probability of buckling stress were 1.8 g for parked condition and 0.8 g for cut-off wind speed. It is observed that the effect of wind loading (turbine operation) has a significant effect in addition to seismic loading in the determination of failure probabilities. Acknowledgements This study was supported by TUBITAK 215M805 scientific and technological research project. References American Petroleum Institute: Recommended practice for planning, designing and constructing offshore platforms — working stress design. 2002. Bazeos N., Hatzigeorgiou G.D., Hondros I.D., Karamaneas H., Karabalis D.L., Beskos D.E., 2002. Static, seismic and stability analyses of a prototype wind turbine steel tower. Engineering Structures 24(8), 1015 – 1025. Brincker R., Zhang L., Andersen P., 2001. Modal identification of output-only systems using frequency domain decomposition. Smart Materials and Structures 10, 441-445. Devriendt C., Magalhães F., Weijtjens W., De Sitter G., Cunha Á., Guillaume P., 2014. SHM of offshore wind turbines using automated operational modal analysis. Structural Health Monitoring 13(6), 644 – 659. Diaz O., Suarez L.E., 2014. Seismic analysis of wind turbines. Earthquake Spectra 30(2), 743 – 765. Hansen M.H., Thomsen K., Fuglsang P., Knudsen T., 2006. Two methods for estimating aeroelastic damping of operational wind turbine modes from experiments. Wind Energy 9(1 – 2), 179 – 191. Hu W.H., Thöns S., Rohrmann R.G., Said S., Rücker W., 2015. Vibration-based structural health monitoring of a wind turbine system. Part I: resonance phenomenon. Engineering Structures 89, 260 – 272. Hu W.H., Thöns S., Rohrmann R.G., Said S., Rücker W., 2015. Vibration-based structural health monitoring of a wind turbine system. Part II: environmental/operational effects on dynamic properties. Engineering Structures 89, 273 – 290. Jonkman J.M., Buhl M.L.: FAST user ’s guide. Report No. NREL/EL -500-38230. National Renewable Energy Laboratory, 2005. Katsanos E.I., Thöns S., Georgakis C.T., 2016. Wind turbines and seismic hazard: a state of the art review. Wind Energy 19, 2113 – 2133. Mo R., Kang H., Li M., Zhao X., 2017. Seismic fragility analysis of monopile offshore wind turbines under different operational conditions. Energies 10(7), 1037. Nuta E., Christopoulos C., Packer J.A., 2011. Methodology for seismic risk assessment for tubular steel wind turbine towers: application to Canadian seismic environment. Can J Civil Engineering 38(3), 293 – 304. Oliveira G., Magalhaes F., Cunha A., Caetano E., 2016. Development and implementation of a continuous dynamic monitoring system in a wind turbine. J. Civil Structural Health Monitoring 6(3):343 – 353. Oliveira G., Magalhaes F., Cunha A., Caetano E., 2018a. Continuous dynamic monitoring of an onshore wind turbine. Engineering Structures 164, 22 – 39. Oliveira G., Magalhaes F., Cunha A., Caetano E., 2018b. Vibration-based damage detection in a wind turbine using 1 year of data. Structural Control Health Monitoring 25(11), e2238. Patil A., Jung S., Kwon O.S., 2016 Structural performance of a parked wind turbine tower subjected to strong ground motions. Engineering Structures 120, 92 – 102.