Reliability of design approaches for axially loaded offshore piles and its consequences with respect to the North Sea

Publikation: Beitrag in FachzeitschriftArtikelForschungPeer-Review

Autoren

  • Kirill A. Schmoor
  • Martin Achmus
  • Aligi Foglia
  • Maik Wefer

Organisationseinheiten

Externe Organisationen

  • Fraunhofer-Institut für Windenergiesysteme (IWES)
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Details

OriginalspracheEnglisch
Seiten (von - bis)1112-1121
Seitenumfang10
FachzeitschriftJournal of Rock Mechanics and Geotechnical Engineering
Jahrgang10
Ausgabenummer6
Frühes Online-Datum7 Aug. 2018
PublikationsstatusVeröffentlicht - Dez. 2018

Abstract

In the near future, several offshore wind farms are planned to be built in the North Sea. Therefore, jacket and tripod constructions with mainly axially loaded piles are suitable as support structures. The current design of axial bearing resistance of these piles leads to deviant results regarding the pile resistance when different design methods are adopted. Hence, a strong deviation regarding the required pile length must be addressed. The reliability of a design method can be evaluated based on a model error which describes the quality of the considered design method by comparing measured and predicted pile bearing resistances. However, only few pile load tests are reported with regard to the boundary conditions in the North Sea. This paper presents 6 large-scale axial pile load tests which were incorporated within a new model error approach for the current design methods used for the axial bearing resistance, namely API Main Text method and cone penetration test (CPT)-based design methods, such as simplified ICP-05, offshore UWA-05, Fugro-05 and NGI-05 methods. Based on these new model errors, a reliability-based study towards the safety was conducted by performing a Monte-Carlo simulation. In addition, consequences regarding the deterministic pile design in terms of quality factors were evaluated. It is shown that the current global safety factor (GSF) prescribed and the partial safety factors are only valid for the API Main Text and the offshore UWA-05 design methods; whereas for the simplified ICP-05, Fugro-05 and NGI-05 design methods, an increase in the required embedded pile length and thus in the GSF up to 2.69, 2.95 and 3.27, respectively, should be considered to satisfy the desired safety level according to DIN EN 1990 of β = 3.8. Further, quality factors for each design method on the basis of all reliability-based design results were derived. Hence, evaluation of each design method regarding the reliability of the pile capacity prediction is possible.

ASJC Scopus Sachgebiete

Zitieren

Reliability of design approaches for axially loaded offshore piles and its consequences with respect to the North Sea. / Schmoor, Kirill A.; Achmus, Martin; Foglia, Aligi et al.
in: Journal of Rock Mechanics and Geotechnical Engineering, Jahrgang 10, Nr. 6, 12.2018, S. 1112-1121.

Publikation: Beitrag in FachzeitschriftArtikelForschungPeer-Review

Schmoor, KA, Achmus, M, Foglia, A & Wefer, M 2018, 'Reliability of design approaches for axially loaded offshore piles and its consequences with respect to the North Sea', Journal of Rock Mechanics and Geotechnical Engineering, Jg. 10, Nr. 6, S. 1112-1121. https://doi.org/10.1016/j.jrmge.2018.06.004, https://doi.org/10.15488/3879
Schmoor, K. A., Achmus, M., Foglia, A., & Wefer, M. (2018). Reliability of design approaches for axially loaded offshore piles and its consequences with respect to the North Sea. Journal of Rock Mechanics and Geotechnical Engineering, 10(6), 1112-1121. https://doi.org/10.1016/j.jrmge.2018.06.004, https://doi.org/10.15488/3879
Schmoor KA, Achmus M, Foglia A, Wefer M. Reliability of design approaches for axially loaded offshore piles and its consequences with respect to the North Sea. Journal of Rock Mechanics and Geotechnical Engineering. 2018 Dez;10(6):1112-1121. Epub 2018 Aug 7. doi: 10.1016/j.jrmge.2018.06.004, 10.15488/3879
Schmoor, Kirill A. ; Achmus, Martin ; Foglia, Aligi et al. / Reliability of design approaches for axially loaded offshore piles and its consequences with respect to the North Sea. in: Journal of Rock Mechanics and Geotechnical Engineering. 2018 ; Jahrgang 10, Nr. 6. S. 1112-1121.
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title = "Reliability of design approaches for axially loaded offshore piles and its consequences with respect to the North Sea",
abstract = "In the near future, several offshore wind farms are planned to be built in the North Sea. Therefore, jacket and tripod constructions with mainly axially loaded piles are suitable as support structures. The current design of axial bearing resistance of these piles leads to deviant results regarding the pile resistance when different design methods are adopted. Hence, a strong deviation regarding the required pile length must be addressed. The reliability of a design method can be evaluated based on a model error which describes the quality of the considered design method by comparing measured and predicted pile bearing resistances. However, only few pile load tests are reported with regard to the boundary conditions in the North Sea. This paper presents 6 large-scale axial pile load tests which were incorporated within a new model error approach for the current design methods used for the axial bearing resistance, namely API Main Text method and cone penetration test (CPT)-based design methods, such as simplified ICP-05, offshore UWA-05, Fugro-05 and NGI-05 methods. Based on these new model errors, a reliability-based study towards the safety was conducted by performing a Monte-Carlo simulation. In addition, consequences regarding the deterministic pile design in terms of quality factors were evaluated. It is shown that the current global safety factor (GSF) prescribed and the partial safety factors are only valid for the API Main Text and the offshore UWA-05 design methods; whereas for the simplified ICP-05, Fugro-05 and NGI-05 design methods, an increase in the required embedded pile length and thus in the GSF up to 2.69, 2.95 and 3.27, respectively, should be considered to satisfy the desired safety level according to DIN EN 1990 of β = 3.8. Further, quality factors for each design method on the basis of all reliability-based design results were derived. Hence, evaluation of each design method regarding the reliability of the pile capacity prediction is possible.",
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T1 - Reliability of design approaches for axially loaded offshore piles and its consequences with respect to the North Sea

AU - Schmoor, Kirill A.

AU - Achmus, Martin

AU - Foglia, Aligi

AU - Wefer, Maik

N1 - Funding Information: The experimental work and the subsequent data interpretation of this contribution have been carried out as part of the European Union funded project Integrated Research Project Wind ( IRPWind, European Union Seventh Framework Program under Grant No. 609795 ).

PY - 2018/12

Y1 - 2018/12

N2 - In the near future, several offshore wind farms are planned to be built in the North Sea. Therefore, jacket and tripod constructions with mainly axially loaded piles are suitable as support structures. The current design of axial bearing resistance of these piles leads to deviant results regarding the pile resistance when different design methods are adopted. Hence, a strong deviation regarding the required pile length must be addressed. The reliability of a design method can be evaluated based on a model error which describes the quality of the considered design method by comparing measured and predicted pile bearing resistances. However, only few pile load tests are reported with regard to the boundary conditions in the North Sea. This paper presents 6 large-scale axial pile load tests which were incorporated within a new model error approach for the current design methods used for the axial bearing resistance, namely API Main Text method and cone penetration test (CPT)-based design methods, such as simplified ICP-05, offshore UWA-05, Fugro-05 and NGI-05 methods. Based on these new model errors, a reliability-based study towards the safety was conducted by performing a Monte-Carlo simulation. In addition, consequences regarding the deterministic pile design in terms of quality factors were evaluated. It is shown that the current global safety factor (GSF) prescribed and the partial safety factors are only valid for the API Main Text and the offshore UWA-05 design methods; whereas for the simplified ICP-05, Fugro-05 and NGI-05 design methods, an increase in the required embedded pile length and thus in the GSF up to 2.69, 2.95 and 3.27, respectively, should be considered to satisfy the desired safety level according to DIN EN 1990 of β = 3.8. Further, quality factors for each design method on the basis of all reliability-based design results were derived. Hence, evaluation of each design method regarding the reliability of the pile capacity prediction is possible.

AB - In the near future, several offshore wind farms are planned to be built in the North Sea. Therefore, jacket and tripod constructions with mainly axially loaded piles are suitable as support structures. The current design of axial bearing resistance of these piles leads to deviant results regarding the pile resistance when different design methods are adopted. Hence, a strong deviation regarding the required pile length must be addressed. The reliability of a design method can be evaluated based on a model error which describes the quality of the considered design method by comparing measured and predicted pile bearing resistances. However, only few pile load tests are reported with regard to the boundary conditions in the North Sea. This paper presents 6 large-scale axial pile load tests which were incorporated within a new model error approach for the current design methods used for the axial bearing resistance, namely API Main Text method and cone penetration test (CPT)-based design methods, such as simplified ICP-05, offshore UWA-05, Fugro-05 and NGI-05 methods. Based on these new model errors, a reliability-based study towards the safety was conducted by performing a Monte-Carlo simulation. In addition, consequences regarding the deterministic pile design in terms of quality factors were evaluated. It is shown that the current global safety factor (GSF) prescribed and the partial safety factors are only valid for the API Main Text and the offshore UWA-05 design methods; whereas for the simplified ICP-05, Fugro-05 and NGI-05 design methods, an increase in the required embedded pile length and thus in the GSF up to 2.69, 2.95 and 3.27, respectively, should be considered to satisfy the desired safety level according to DIN EN 1990 of β = 3.8. Further, quality factors for each design method on the basis of all reliability-based design results were derived. Hence, evaluation of each design method regarding the reliability of the pile capacity prediction is possible.

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KW - Quality factors

KW - System reliability

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