Offshore wind turbines (OWTs) might be subjected to seismic loads with different peak accelerations during operation in the actively seismic regions. The earthquakes might be a potential risk for the OWTs due to its stochastic nature. Earthquake with wind and wave loads could act on OWT at the same time; thus, the structural responses of such OWTs should be analyzed taking into consideration the reasonable load combinations. Based on the hydro-elastic similarity, an integrated model of the combined National Renewable Energy Laboratory (NREL) 5 MW wind turbine and a practical pentapod substructure is designed for testing. The governing equations of motion of the integrated OWT are established. The dynamic tests and numerical analysis of the OWT model are performed under different combinations of seismic, wind, and sea load conditions. The El Centro and American Petroleum Institute (API)-based synthesized seismic waves with different peak ground accelerations (PGAs) are considered in this study. The numerical results are in good agreement with the experimental ones. The coupling effect of the OWT structure under the combined load conditions is demonstrated from the experimental and numerical results. The results indicate that the interaction of earthquake, wind, wave, and current should be taken into account in order to obtain proper structural response, especially with small PGA.

References

References
1.
Det Norske Veritas
,
2002
,
Guidelines for Design of Wind Turbines
,
DNV
,
Kongens Lyngby, Denmark
.
2.
Germanischer Lloyd
,
2012
,
Guideline for the Certification of Offshore Wind Turbines
,
GL
,
Hamburg, Germany
.
3.
International Electrotechnical Commission
,
2012
, “
Wind Turbine—Part 1: Design Requirements
,” IEC Geneva, Switzerland, Standard No. IEC 61400-1.
4.
Penzien
,
J.
,
Kaul
,
M. K.
, and
Berge
,
B.
,
1972
, “
Stochastic Response of Offshore Towers to Random Sea Waves and Strong Motion Earthquakes
,”
Comput. Struct.
,
2
(
5
), pp.
733
756
.
5.
Prowell
,
I.
, and
Veers
,
P.
,
2009
, “
Assessment of Wind Turbine Seismic Risk: Existing Literature and Simple Study of Tower Moment Demand
,” Sandia
Report No. 2009-1100
,
Sandia National Laboratories
,
Albuquerque, NM
.
6.
Bazeos
,
N.
,
Hatzigeorgiou
,
G. D.
,
Hondros
,
I. D.
,
Karamaneas
,
H.
,
Karabalis
,
D. L.
, and
Beskos
,
D. E.
,
2002
, “
Static, Seismic and Stability Analyses of a Prototype Wind Turbine Steel Tower
,”
Eng. Struct.
,
24
(
8
), pp.
1015
1025
.
7.
Jonkman
,
J. M.
, and
Buhl
,
M. L.
, Jr.
,
2005
, “
FAST User's Guide
,”
Technical Report No. NREL/EL-500-38230
,
National Renewable Energy Laboratory
,
Golden, CO
.
8.
Asareh
,
M. A.
, and
Prowell
,
I.
,
2011
, “
Seismic Loading for FAST
,”
Subcontract Report No. NREL/SR-5000-53872
,
National Renewable Energy Laboratory
,
Golden, CO
.
9.
Zhao
,
X.
, and
Maisser
,
P.
,
2006
, “
Seismic Response Analysis of Wind Turbine Towers Including Soil-Structure Interaction
,”
Proc. Inst. Mech. Eng., Part K
,
220
(
1
), pp.
53
61
.
10.
Kim
,
D. H.
,
Lee
,
S. G.
, and
Lee
,
I. K.
,
2014
, “
Seismic Fragility Analysis of 5 MW Offshore Wind Turbine
,”
Renewable Energy
,
65
, pp.
250
256
.
11.
Prowell
,
I.
,
Veletzos
,
M.
,
Elgamal
,
A.
, and
Restrepo
,
J.
,
2009
, “
Experimental and Numerical Seismic Response of a 65 kW Wind Turbine
,”
J. Earthquake Eng.
,
13
(
8
), pp.
1172
1190
.
12.
Prowell
,
I.
,
2010
, “
An Experimental and Numerical Study of Wind Turbine Seismic Behavior
,” Ph.D. thesis, University of California, San Diego, CA.
13.
Zheng
,
X. Y.
,
Li
,
H.
,
Rong
,
W.
, and
Li
,
W.
,
2015
, “
Joint Earthquake and Wave Action on the Monopile Wind Turbine Foundation: An Experimental Study
,”
Mar. Struct.
,
44
, pp.
125
141
.
14.
Chen
,
J.
,
Liu
,
Y.
, and
Bai
,
X.
,
2015
, “
Shaking Table Test and Numerical Analysis of Offshore Wind Turbine Tower Systems Controlled by TLCD
,”
Earthquake Eng. Eng. Vib.
,
14
(
1
), pp.
55
75
.
15.
Jonkman
,
J.
,
Butterfield
,
S.
,
Musial
,
W.
, and
Scott
,
G.
,
2009
, “
Definition of a 5-MW Wind Turbine Reference for Offshore System Development
,”
Technical Report No. NREL/TP-500-38060
,
National Renewable Energy Laboratory
,
Golden, CO
.
16.
Wang
,
W. H.
,
Gao
,
Z.
,
Moan
,
T.
,
Li
,
X.
, and
Wang
,
B.
,
2016
, “
Model Test and Numerical Analysis of an Offshore Bottom Fixed Pentapod Wind Turbine Under Seismic Loads
,”
ASME
Paper No. OMAE2016-54499.
17.
Chakrabarti
,
S.
,
1998
, “
Physical Model Testing of Floating Offshore Structures
,”
Marine Technology Society Dynamic Positioning Conference
, Houston, TX, Oct. 13–14.
18.
Chakrabarti
,
S.
,
2005
,
Handbook of Offshore Engineering
,
Elsevier Press
,
Amsterdam, The Netherlands
.
19.
American Petroleum Institute
,
2007
,
Recommended Practice for Design and Construction of Fixed Offshore Platforms
,
API
,
Washington, DC
.
20.
Det Norske Veritas
,
2014
,
Design of Offshore Wind Turbine Structures, DNV-OS-J101
,
DNV
,
Oslo, Norway
.
21.
Clough
,
R. W.
, and
Penzien
,
J.
,
1975
,
Dynamics of Structures
,
McGraw-Hill Press
,
New York
.
22.
ANSYS
,
2012
,
ANSYS Standard User's Manual
,
ANSYS Inc.
,
Canonsburg, PA
.
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