Sustainable Marine Structures

Dynamic Assessment of OWT under Coupled Seismic and Sea-wave Motions

Maryam Massah Fard

Department of Civil Engineering, Ozyegin University, Istanbul, 34794, Turkey

Ayfer Erken

Department of Civil Engineering, Dogus University, Istanbul, 34775, Turkey

Atilla Ansal

Department of Civil Engineering, Ozyegin University, Istanbul, 34794, Turkey

DOI: https://doi.org/10.36956/sms.v5i2.884

Received: 3 July 2023; Revised: 30 August 2023; Accepted: 25 September 2023; Published: 29 September 2023

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Abstract

The effect of soil-monopile-structure interaction is of great importance in the design of offshore wind turbines (OWTs). Although sea waves play the most effective role in the performance of OWTs, the coupled effect of sea-wave loads and seismic motion on the performance of the OWT system in seismic-prone areas is a factor that is less investigated and should not be ignored. In this regard, a 2-D porous model based on Biot’s poro-elastic theory is considered to capture the pore water pressure generation in the soil domain surrounding the OWT foundation. The coupled effect of sea waves and seismic motion through a comparative study is considered for the reference OWT system based on the monopile foundation by using the FE program, OpenSees. The results of the analyses are presented in specific locations. Upon the obtained results, the dynamic behavior of the OWT system and the possibility of liquefaction in the soil surrounding the OWT during applied loads are investigated and compared. This comparison is a good representative of the effect of the seismic motion on the performance of the OWT system and the soil medium by considering soil-monopile-structure interaction in seismic-prone areas.

Keywords: Offshore wind turbines, Seismic motion, Sea-wave loads, Pore water pressure generation

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References

[1] Bhattacharya, S., Nikitas, G., Jalbi, S., 2018. On the use of scaled model tests for analysis and design of offshore wind turbines. In: Krishna, A., Dey, A., Sreedeep, S. (eds) Geotechnics for natural and engineered sustainable technologies. Developments in Geotechnical Engineering. Singapore: Springer. pp. 107-129.

[2] Mazzoni, S., McKenna, F., Fenves, G.L., 2010. OpenSees [Internet]. Available from: http://opensees.berkeley.edu/wiki/index.php/Main_Page

[3] Sadowski, A.J., Camara, A., Málaga-Chuquitaype, C., et al., 2017. Seismic analysis of a tall metal wind turbine support tower with realistic geometric imperfections. Earthquake Engineering & Structural Dynamics. 46(2), 201-219.

[4] De Risi, R., Bhattacharya, S., Goda, K., 2018. Seismic performance assessment of monopile-supported offshore wind turbines using unscaled natural earthquake records. Soil Dynamics and Earthquake Engineering. 109, 154-172.

[5] Yang, C.B., Wang, R., Zhang, J.M. (editors), 2018. Seismic analysis of monopile supported offshore wind turbine. International Conference on Geotechnical and Earthquake Engineering; 2018 Oct 20-21; Chongqing, China.

[6] Mistry, H.K., Lombardi, D., 2020. Role of SSI on seismic performance of nuclear reactors: A case study for a UK nuclear site. Nuclear Engineering and Design. 364, 110691.

[7] Esfeh, P.K., Kaynia, A.M., 2020. Earthquake response of monopiles and caissons for Offshore Wind Turbines founded in liquefiable soil. Soil Dynamics and Earthquake Engineering. 136, 106213.

[8] Recommended Practice for Planning, Designing and Constructing Fixed Offshore Platforms—Working Stress Design [Internet]. API-American Petroleum Institute; 2003. Available from: https://www.academia.edu/37079635/Recommended_Practice_for_Planning_Designing_and_Constructing_Fixed_Offshore_Platforms_Working_Stress_Design_API_RECOMMENDED_PRACTICE_2A_WSD_RP_2A_WSD_TWENTY_FIRST_EDITION_DECEMBER_2000

[9] DNVGL-ST-0437 Loads and Site Conditions for Wind Turbines [Internet]. DET NORSKE VERITAS. Available from: https://www.dnv.com/energy/standards-guidelines/dnv-st-0437-loads-and-site-conditions-for-wind-turbines.html

[10] Bhattacharya, S., De Risi, R., Lombardi, D., et al., 2021. On the seismic analysis and design of offshore wind turbines. Soil Dynamics and Earthquake Engineering. 145, 106692.

[11] Zheng, X.Y., Li, H., Rong, W., et al., 2015. Joint earthquake and wave action on the monopile wind turbine foundation: An experimental study. Marine Structures. 44, 125-141.

[12] Prevost, J.H., 1985. A simple plasticity theory for frictional cohesionless soils. International Journal of Soil Dynamics and Earthquake Engineering. 4(1), 9-17.

[13] Lacy, S., 1986. Numerical procedures for nonlinear transient analysis of two-phase soil system [Ph.D. thesis]. Princeton: Princeton University.

[14] Cubrinovski, M., Ishihara, K., 1998. State concept and modified elastoplasticity for sand modelling. Soils and Foundations. 38(4), 213-225.

[15] Elgamal, A., Yang, Z., Parra, E., et al., 2003. Modeling of cyclic mobility in saturated cohesionless soils. International Journal of Plasticity. 19(6), 883-905.

[16] Yang, Z., Elgamal, A., Parra, E., 2003. Computational model for cyclic mobility and associated shear deformation. Journal of Geotechnical and Geoenvironmental Engineering. 129(12), 1119-1127.

[17] Yang, Z., Lu, J., Elgamal, A., 2008. OpenSees Soil Models and Solid-Fluid Fully Coupled Elements [Internet]. Available from: http://www.soilquake.net/opensees/OSManual_UCSD_soil_models_2008.pdf

[18] Ishihara, K., Tatsuoka, F., Yasuda, S., 1975. Undrained deformation and liquefaction of sand under cyclic stresses. Soils and Foundations. 15(1), 29-44.

[19] Khosravifar, A., 2012. Analysis and design for inelastic structural response of extended pile shaft foundations in laterally spreading ground during earthquakes [Ph.D. thesis]. Davis: University of California.

[20] Karimi, Z., Dashti, S., 2016. Numerical and centrifuge modeling of seismic soil-foundation-structure interaction on liquefiable ground. Journal of Geotechnical and Geoenvironmental Engineering. 142(1), 04015061.

[21] Corciulo, S., Zanoli, O., Pisanò, F., 2017. Transient response of offshore wind turbines on monopiles in sand: Role of cyclic hydro-mechanical soil behaviour. Computers and Geotechnics. 83, 221-238.

[22] Fard, M.M., Erken, A., Erkmen, B., et al., 2022. Analysis of offshore wind turbine by considering soil-pile-structure interaction: Effects of foundation and sea-wave properties. Journal of Earthquake Engineering. 26(14), 7222-7244. DOI: https://doi.org/10.1080/13632469.2021.1961936

[23] Lysmer, J., Kuhlemeyer, R.L., 1969. Finite dynamic model for infinite media. Journal of the Engineering Mechanics Division. 95(4), 859-877.

[24] DNVGL-OS-J101 Design of Offshore Wind Turbine Structures [Internet]. DET NORSKE VERITAS. Available from: https://docplayer.net/21082564-Design-of-offshore-wind-turbine-structures.html

[25] PEER Strong Ground Motion Databases [Internet] [cited 2021 Jun 23]. Available from: https://peer.berkeley.edu/peer-strong-ground-motion-databases

[26] Geng, F., Yang, W., Nadimi, S., et al., 2023. Study for predicting the earthquake-induced liquefaction around the monopile foundation of offshore wind turbines. Ocean Engineering. 268, 113421.

[27] Joyner, W.B., Chen, A.T., 1975. Calculation of nonlinear ground response in earthquakes. Bulletin of the Seismological Society of America. 65(5), 1315-1336.