TY - JOUR

T1 - Recovery-based error estimation in the dynamic analysis of offshore wind turbine monopile foundations

AU - Bayat, M.

AU - Ghorashi, S. Sh

AU - Amani, J.

AU - Andersen, L. V.

AU - Ibsen, L. B.

AU - Rabczuk, Timon

AU - Zhuang, Xiaoying

AU - Talebi, H.

N1 - Funding information: The authors highly appreciate the financial support provided by Danish Energy Development and Demonstration Programme (EUDP) via the project “Monopile cost reduction and demonstration by joint applied research”. And also, authors would like to gratefully acknowledge the DFG-Research Training Group 1462 and Institute of Structure Mechanics , both at the Bauhaus-Universität Weimar, for the financial support.

PY - 2015/8/7

Y1 - 2015/8/7

N2 - Offshore wind turbine foundations are affected by cyclic loads due to oscillatory kinematic loads, such as those from wind, waves, and earthquakes. Monopiles are often used as a foundation concept for offshore windmill turbines. In this study, coupled dynamic equations with the u-P formulation for low-frequency load are considered for an offshore wind turbine monopile foundation, to present the response in terms of pore water pressure (PWP), stress and strain distribution in an elastic porous medium at regions around the monopile foundation. Different stress recovery techniques based on the Zienkeiwicz-Zhu (ZZ) error estimator namely, super-convergent patch recovery (SPR), weighted super-convergent patch recovery (WSPR), and L2-projection techniques are also investigated to recover the stresses at nodal points in the finite element method. To estimate errors in the time domain when performing transient simulations, three recovery processes are used with different meshes. The convergence of the dynamic problem is also studied. The results are verified with findings in the literature, revealing that the time period of effective stresses follows the applied load frequency. In conclusion, the history of the shear stress can have an important effect on the shear stress distribution, making it asymmetric in the time domain.

AB - Offshore wind turbine foundations are affected by cyclic loads due to oscillatory kinematic loads, such as those from wind, waves, and earthquakes. Monopiles are often used as a foundation concept for offshore windmill turbines. In this study, coupled dynamic equations with the u-P formulation for low-frequency load are considered for an offshore wind turbine monopile foundation, to present the response in terms of pore water pressure (PWP), stress and strain distribution in an elastic porous medium at regions around the monopile foundation. Different stress recovery techniques based on the Zienkeiwicz-Zhu (ZZ) error estimator namely, super-convergent patch recovery (SPR), weighted super-convergent patch recovery (WSPR), and L2-projection techniques are also investigated to recover the stresses at nodal points in the finite element method. To estimate errors in the time domain when performing transient simulations, three recovery processes are used with different meshes. The convergence of the dynamic problem is also studied. The results are verified with findings in the literature, revealing that the time period of effective stresses follows the applied load frequency. In conclusion, the history of the shear stress can have an important effect on the shear stress distribution, making it asymmetric in the time domain.

KW - Coupled equations

KW - Cyclic load

KW - Dynamic behavior

KW - Offshore foundation

KW - Recovery-based error estimation

UR - http://www.scopus.com/inward/record.url?scp=84938792470&partnerID=8YFLogxK

U2 - 10.1016/j.compgeo.2015.07.012

DO - 10.1016/j.compgeo.2015.07.012

M3 - Article

AN - SCOPUS:84938792470

VL - 70

SP - 24

EP - 40

JO - Computers and Geotechnics

JF - Computers and Geotechnics

SN - 0266-352X

ER -