Reliability Analysis of Monopile for a Offshore Wind Turbine Using Response Surface Method

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** ⍕┾ญᕽ⊹ ݡ⢽ ([email protected])

Received April 8, 2013/ revised June 28, 2013/ accepted August 13, 2013

Copyright ⵑ 2013 by the Korean Society of Civil Engineers

ǣǣȀȀǤǤȀͳͲǤͳʹ͸ͷʹȀǤʹͲͳ͵Ǥ͵͵Ǥ͸ǤʹͶͲͳ ǤǤǤ

ⴏᢳ′#Ꮾ≓ⴂ#ⴲⱧ㬚#㬲♿㩋ᷣⱧ#⁦᜶㣊ⴺⴖ#⢞Ṯ⛯#㬲⛛

ଗ׊ࠨȵ׌ֈ஼ȵ׌ก઴

Yoon, Gil Lim*, Kim, Kwang Jin**, Kim, Hong Yeon***

Reliability Analysis of Monopile for a Offshore Wind Turbine Using Response Surface Method

ABSTRACT

Reliability analysis with response surface method (RSM) was peformed for a offshore wind turbine (OWT) monopile, which is one of mostly used foundations under 25m seawater depth in the world. The behaviors of a real OWT monopile installed into sandy soils subjected to offshore environmental loads such as wind and wave were analysed using reliability design program (HSRBD) developed in KIOST. Sensitivity analysis of design variables for a OWT monopile with 6m diameter showed that the larger in pile diameter the smaller in probability of failure (Pf) of a horizontal deflection and a rotational angle at a pile top, but at a greater than 7m of pile diameter, the reduction rate of Pf was almost constant. It is a necessary that appropriate local design criteria should be designated as soon as possible because there were significant differences on horizontal deflections; Pf was 60% at a minimum criteria 15mm deflection, however, 1.5% Pf when 60mm deflection using 1% of pile diameter from local design criterion standard. Finally, friction angle of sand among many design variables was found most influential design factor in OWT monopile design, and a sensitivity analysis is found an important process to understand which design variables can mostly reduce Pf with a optimum design for maintaining OWT stability.

Key words : Monopile foundation, Response surface method, Reliability analysis, Offshore wind turbine, Importance sampling

Ⅹಾ

᮲ݖ໕ʑჶ(RSM)ᮥᯕᬊ⦹ᩍ⧕ᔢ⣮ಆ(OWT) ༉י❭ᯝᨱݡ⦽ᝁ഑ᖒ⧕ᕾᮥᙹ⧪⦹ᩡ݅. ༉י❭ᯝᮡ⧕ᙹ໕ᮝಽᇡ░15m ʫᯕᨱᖅ⊹ࡹ

Łᔍḩ☁ᨱɝ᯦ࡹ۵᳑ÕᮝಽŁಅ⦹ᩡ݅. ⣮⦹ᵲၰ❭௲⦹ᵲŝzᮡ⧕᧲⪹Ğ⦹ᵲᯕ᯲ᬊ⦹۵OWT ༉י❭ᯝᨱݡ⦽ᝁ഑ᖒ⧕ᕾᮡ

KIOSTᨱᕽ}ၽࡽᝁ഑ᖒ⧕ᕾ⥥ಽəఉᯙHSRBDෝᯕᬊ⦹ᩡ݅. OWT ༉י❭ᯝ(ḢĞ6m)᮹ᖅĥᄡᙹᨱݡ⦽ၝqࠥᇥᕾᮥᙹ⧪⦽đŝ

❭ᯝḢĞᯕ᷾a⧁ᙹಾ❭ᯝࢱᇡᨱᕽ᮹ᙹ⠪ᄡ᭥ၰ⫭ᱥbᨱݡ⦽❭ƕ⪶ශᮡqᗭ⦹ӹḢĞᯕ7m ᯕᔢᯕࡹ۵Ğᬑ❭ƕ⪶ශ᮹qᗭᮉᮡ᯲

ᦥᲙÑ᮹ᯝᱶ⧕ḡ۵äᮝಽӹ┡ԍ݅. ⦽⠙, ǎԕʑᵡaᬕߑ❭ᯝḢĞ᮹1%ෝ⨩ᬊᙹ⠪ᄡ᭥(60mm)ಽᱢᬊ⦹۵Ğᬑ❭ᯝ᮹❭ƕ⪶ශᮡ

1.5%ᯕӹ↽ᗭʑᵡᯙ15mmಽŁಅ⦹۵Ğᬑ❭ƕ⪶ශᮡ60%ಽⓑ₉ᯕaၽᔾ⦹အಽᯕᨱݡ⦽ᱢᱩ⦽ᖅĥʑᵡ᮹ᱶพᯕ᫵Ǎࡽ݅. ษḡ สᮝಽOWT ༉י❭ᯝ᮹݅᧲⦽ᖅĥᄡᙹaᬕߑʑⅩḡၹ(ᔍḩ☁)ᨱݡ⦽ԕᇡษₑb᮹ᇩ⪶ᝅᖒᯕⓑĞᬑᯕäᯕ❭ᯝÑ࠺ᨱaᰆⓑᩢ⨆

ᮥၙ⊹۵äᮝಽᇥᕾࡹᨩᮝ໑, ၝqࠥᇥᕾđŝ۵↽ᱢᖅĥ᪡❭ƕ⪶ශqᗭෝ᭥⧕ᨕਁ⦽ᱩ₉a⦥᫵⦽ḡෝᅕᩍᵡ݅.

áᔪᨕ༉י❭ᯝ, ᮲ݖ໕ʑჶ, ᝁ഑ᖒ⧕ᕾ, ⧕ᔢ⣮ಆ, ᵲ᫵ࠥ⇵⇽ჶ

ݓъėॡ

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1. ᕽು

┥ᗭ႑⇽ǭᱽ⦽ŝᝁᰍᔾᨱթḡ}ၽᯕჵḡǍᱢᯙ⪵ࢱa

ࢉᨱ ঑௝ ⣮ಆၽᱥ᜽ᖅ Õᖅᨱ ݡ⦽ šᝍŝ ᩑǍa ⪶ݡࡹŁ

ᯩ݅. ✚⯩, ᬑญӹ௝᮹Ğᬑǎ☁໕ᱢᯕ᳢ᮡၹ໕⧕᧲Ŗe⪽ᬊᨱ

ๅᬑᮁญ⦽᯦ḡෝaḡŁᯩᨕ⧕ᔢ⣮ಆၽᱥ᯦ࠥᨱݡ⦽šᝍᯕ

Ⓧ݅. ⧕ᔢ⪹ĞᮡእƱᱢŁၡࠥ᮹ၵ௭ᨱթḡaᦩᱶᱢᮝಽŖɪ

ࡹŁᗭᮭŖ⧕᪡ᱥ❭ᰆᧁ॒ၝᬱྙᱽࠥᨧᨕၽᱥ᜽ᖅ᮹Õᖅŝ

ᬕᩢᨱᬑಅࡹ۵ᱽ⦽ᯕๅᬑᱢʑࠥ⦹݅. ⧕ᔢᨱ⣮ಆၽᱥ᜽ᖅᮥ

Õᖅ⧁ভӹᖡ, ት౩ᯕऽၰ┡ᬭ॒ᔢᇡǍ᳑᮹ᯱᵲŝ⣮⦹ᵲ

ၰ❭௲⦹ᵲ, a࠺ᨱ঑ෙ༉ູ✙॒ၽᔾࡹ۵᫙ಆᨱᱡ⧎⦹ʑ

᭥⧕⧕ᱡḡၹᨱᖅ⊹ࡹ۵ʑⅩŖჶ᮹᳦ඹࠥ⩥ᰍʭḡฯᯕ}ၽ

ࡹᨕ᪵݅. ᯕ్⦽ʑⅩŖჶᮡᵝಽĞᱽᖒŝᦩᱶᖒᮥɚݡ⪵⦹۵

⊂໕ᨱᕽᙹᝍ, ⧕ᱡḡၹᔢ┽, ┡ᬭ᮹׳ᯕ॒ŝᩑšࡹᨕᇥඹࡹŁ

ᖅĥᨱ ⪽ᬊࡹᨩ݅.

⧕ᔢ⣮ಆǍ᳑ྜྷᮥ᜽Ŗ⦹ᩍᬕᬊ⦹۵Ğᬑᨱᮂᔢᨱᖅ⊹ࡹ۵

Ǎ᳑ྜྷŝ۵ə⪹Ğ᳑Õᯕๅᬑ݅෕အಽʑⅩŖჶࠥǑั૾⩶᮹

❭ᯝʑⅩᯕ᫙ᨱᵲಆ᜾, ᯱ⍴᜾, ༉י❭ᯝ᜾, ᕾᖹ❭ᯝ᜾॒݅᧲

⦽⩶᜾ᮝಽ}ၽࡹᨩ݅. əญŁ↽ɝᨱ۵Ł⬉ᮉ·ݡᬊప᮹⣮ಆ░

ኩ}ၽᯕĥᗮᱢᮝಽ ᯕ൉ᨕḱᨱ঑௝ᕽᱢᬊࡹ۵ʑⅩŖჶࠥ

ᅕ݅ ԕ⦹ ḡḡಆᯕ ⓑ ⩶᜾ᮝಽ ݡ⩶⪵ ࡹᨕaŁ ᯩ݅. ✚⯩,

⧕ᔢ⣮ಆ⦹ᇡʑⅩ۵ᦩᱶᖒၰĞᱽᖒ⊂໕ᨱᕽᖅĥʑᚁ᮹ᱶࠥ

a ׳Ł Ğᱽᱢᮝಽ ↽ᱢ⪵⦹ʑ ᭥⦽ ႊ⨆ᮝಽ ᄡ⪵⦹Ł ᯩ۵

⇵ᖙᯕ݅. ⧕ᔢ⣮ಆ Õᖅ᮹ ฯᮡ Ğ⨹ᮥ aḡŁ ᯩ۵ ߕษⓍ᪡

ᩢǎ॒ᮁ౞, ᕾᮁ᜽⇵॒⧕ᔢǍ᳑ྜྷǍ⇶ᨱ᪅௽י⦹ᬑෝaḥ

ၙǎᮥᵲᝍᮝಽ⦽ĥᔢ┽ ᖅĥჶᨱɝe⦽ᖅĥʑᵡᯕ}ၽࡽ

äࠥ ə ᯝ⪹ᯕ௝ ⦹ā݅.

⦽⠙, ݅᧲⦽ʑⅩ⩶᜾ᵲ༉י❭ᯝʑⅩ۵݅ෙʑⅩ⩶᜾ŝ

እƱ⧁ভ⩶┽a݉ᙽ⦹Ł᜽ŖᯕእƱᱢe⠙⦹ᩍ⧕ᔢ᜽Ŗᨱ

ᮁญ⦹໑Ğᱽᖒᯕ୑ᨕӽᰆᱱᮥwŁᯩᨕ⧕ᔢ⣮ಆʑⅩǍ᳑ྜྷ

ಽฯᯕᔍᬊࡹŁᯩ݅. ༉י❭ᯝ᮹⧕ᕾᨱᯩᨕ⧕ᱡḡၹ᮹vᖒᮥ

Łಅ⦹ḡᦫ۵ḡၹŁᱶ᜾ᅕ݅⧕ᱡḡၹ᮹vᖒᮥŁಅ⦹۵aᔢ Łᱶ᜾ŝ॒ᇥ⡍ᜅ⥥ย᜾ᯕᅕ݅ⓑ⮉༉ູ✙ᱡ⧎ᮥwʑভྙᨱ

ᦩᱥ⦽ᖅĥෝ⧁ᙹᯩ݅(Emmanuel et al., 2008). ੱ⦽, ⣮ಆ░ኩ

ት౩ᯕऽ᮹⫭ᱥᬕ࠺ŝŁᮁḥ࠺ᨱ᮹⧕ʑⅩǍ᳑ྜྷᯕš᯦ࡽ⧕

ᱡḡၹᨱᕽ۵ၹᅖ⦹ᵲᯕ᯲ᬊ⦹íࢉᨱ঑௝əᩢ⨆ᮝಽ⦹ᇡʑ

Ⅹᯙั૾᮹ḡḡಆᨱ ၙ⊹۵ḡၹၹಆĥᙹaqᗭ⦹۵Ğ⨆ᯕ

ᯩ݅(Krolis, 2007).

ᅙᩑǍᨱᕽ۵⧕ᔢ⣮ಆʑⅩŖჶaᬕߑ25m ᯕ⦹᮹ᙹᝍᨱᕽ

እƱᱢฯᯕ⪽ᬊࡹŁᯩ۵༉י❭ᯝ᮹⧕ᕾᮥ᭥⦹ᩍǎ᫙ᨱᕽ

}ၽࡽ⣮ಆ░ኩ᮹ᝅᱽ༉ߙᮥᖁᱶ⦹Łəᨱ঑ෙᯱᵲၰᬕᬊ⪹

Ğᮥ Łಅ⦹ᩍ ᱢᬊᯕ a܆⦽ ᯥ᮹᮹ ḡၹ᳑Õ ⦹ᨱᕽ ᝁ഑ᖒ

⧕ᕾᮥ ☖⦹ᩍ ༉י❭ᯝ᮹ Ñ࠺ᮥ ⪶ශುᱢᮝಽ ᇥᕾ⦹ᩡ݅.

2. ᅙםྙ᮹ᙹ⊹⧕ᕾʑჶ

ᝁ഑ᖒ⧕ᕾʑჶ᮹᳦ඹ۵ᖅĥᯱ᮹⠙᮹ᖒᮥŁಅ⦹ᩍaᰆ

݉ᙽ⪵ࡽႊ᜾ᮥ≉⦹۵ᇡᇥĥᙹჶ(౩ᄉ1 ᙹᵡ)ᨱᕽᇡ░⦽ĥᔢ

┽⧉ᙹ᮹⠪Ɂ⊹ੱ۵❭ƕᱱᇡɝᨱᕽɝᔍ⧕ෝ₟۵ɝᔍ⪵ႊჶ (౩ᄉ2 ᙹᵡ), əญŁ⧉ᙹෝɝᔍ⪵⦹ḡᦫŁḢᱲᱢᇥ⦹Ñӹ

ᙹฯᮡӽᙹෝᔾᖒ᜽⍽❭ƕaᯝᨕӹ۵Ğᬑ᮹ᙹෝ₟۵⇵⇽ჶ (౩ᄉ 3 ᙹᵡ)ᨱ ᯕ෕ʑ ʭḡ ๅᬑ ݅᧲⦹݅. ᅙ ᩑǍᨱᕽ۵ ə

aᬕߑɝᔍ⪵ႊჶŝ⇵⇽ჶᮥᯕᬊ⦹ᩍ❭ƕ⪶ශᮥᔑᱶ⦹ᩡ݅.

2.1 ଦۢ࡟׆࣑

⩥ᰍʭḡ❭ᯝ᮹ᙹ⠪Ñ࠺ᮡp-y łᖁᨱ᮹⧕⧕ᕾ⧉ᯕaᰆ

⧊ญᱢᯕ௝᦭ಅᲙᯩᮝ໑, ᯕ్⦽እᖁ⩶p-y Ñ࠺⧕ᕾᮡᮁ⦽᫵ᗭ ჶ(FEM)ᨱ᮹⧕ᯕ൉ᨕḥ݅. ə౑ߑəಽᇡ░᨜ᮥᙹᯩ۵᳦ᗮᄡ ᙹᯙᄡ᭥ӹ⫭ᱥb॒ᖒ܆ᄡᙹ᮹⦽ĥᔢ┽⧉ᙹ۵ᮭ⧉ᙹ(implicit function)᮹⩶┽ᯕအಽḢᱲ⦽ĥᔢ┽⧉ᙹಽᝁ഑ᖒ⧕ᕾᮥᙹ⧪⦹

ʑ۵ᅖᰂ⦹Łฯᮡ᜽eᯕ᫵Ǎࡽ݅. ⦽⠙, ᮲ݖ໕ʑჶ(response surface method; RSM)ᮥᯕᬊ⦹໕ᮭ⧉ᙹ⩶┽᮹⦽ĥᔢ┽⧉ᙹෝ

᧲⧉ᙹ(explicit function)᮹⩶┽ಽɝᔍ⪵aa܆⦹Ł᨜ᨕḥ᧲⧉

ᙹෝ ᯕᬊ⦹໕ ʑ᳕᮹ ႊჶᮝಽ ⧕ᕾᯕ a܆⦹݅.

⦽ĥᔢ┽⧉ᙹෝɝᔍ⪵⧁ভɝᔍ⪵ࡽ⦽ĥᔢ┽⧉ᙹĀƅÞƖß ᷪ, ᮲ݖ໕⩶┽᮹đᱶᮡᝅᱽ⦽ĥᔢ┽⧉ᙹƅÞƖß᮹⩶┽᪡əእᖁ⩶

ᖒᮥqᦩ⧕᧝⦽݅. ᮭ⧉ᙹ⩶┽ᨱᕽ۵ݡ}ƅÞƖßෝ᦭ᙹᨧᮝအ ಽ⩥ᰍʭḡ᮲ݖ໕ᮡŲჵ᭥⦽ྙᱽॅᨱÙℱᱢᬊ⧁ᙹᯩࠥಾ

ᯝၹᱢᯙ ⩶┽ಽ }ၽࡽၵ ᯩ݅. aᰆ ᯝၹᱢᯙ ⩶┽۵ ݅ᮭŝ

zᮡ 2₉ ݅⧎᜾ᯕ݅(Faravelli, 1989).

ĀƅÞƖß á ſâā_{Ƈ á Î}^ƌ ^ƀ^Ƈ^Ɩ^Ƈ^âā_{Ƈ á Î}^ƌ ^Ɓ^Ƈ^Ɩ^Ƈ^Ï ⁽¹⁾

ᩍʑᕽ,ƖƇ᪡ƌᮡ⪶ශᄡᙹ᪡ə}ᙹᯕŁ,ſ,_ƀ_Ƈ ၰƁƇ۵᮲ݖ໕ ᮹⩶┽ෝӹ┡ԕʑ᭥⦽ĥᙹᯕ݅. อ᧞,ĀƅÞƖßaƅÞƖßᅕ݅⭉ᦍ

׳ᮡ ₉ᙹෝ wí ࡽ݅໕ እᱶᔢᱢᯙ ᜾ᯕ ࠥ⇽ࢁ ᙹ ᯩᮥ ᐱ

ᦥܩ௝⢽ᅙᱱ(sample point) ᩢᩎၷᨱᕽĀƅÞƖß᪡ƅÞƖß ᔍᯕᨱ

ⓑ₉ᯕaӹ┡ԁᙹᯩᮝအಽݡ}׳ᮡ₉ᙹ᮹݅⧎᜾ᮡᔍᬊ⦹ḡ

ᦫ۵݅. እಾ2₉݅⧎᜾ᮥᔍᬊ⧉ᯕྜྷญᱢ┡ݚᖒᮡᇡ᳒⦹޵௝

ࠥəäᯕ⦹ӹ᮹ᖅĥᱱ(design point)ᮥᛞí⪶ᯙ⧁ᙹᯩࠥಾ

⦹۵ ݉ᙽ⦹Ł ᨜ʑ ᛍᬕ ๅҥ్ᬕ ໕(surface)ᮥ ᱽŖ⧕ ᵡ݅.

ᯕ۵✚⯩ɝᔍ⪵ࡽ⦽ĥᔢ┽໕ᔢᨱᖅĥᱱᮥ᭥⊹᜽┅۵᮲ݖ໕

ɝᔍ⪵᮹ၹᅖᱢᯙᖅĥ᪡ɝᔍ⪵ࡽ⦽ĥᔢ┽໕ᔢᨱᕽFORMŝ

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Fig. 1. Schematic of a Sample Method

SORMᮥᱢᬊ⦹۵ߑᮁᬊ⦹݅. ᜾ᨱᕽſ,_ƀ_Ƈ ၰƁƇ۵ÏƌâÎ}᮹

ၙḡ᮹ĥᙹᯕ݅. ᯕॅĥᙹsᮡᝅᱽ⦽ĥᔢ┽⧉ᙹƅÞƖßಽᇡ░ᯝಉ ᮹ ⢽ᅙᱱᮥᯕᬊ⦹ᩍ✚ᯕsᇥ⧕(singular value decomposition)

ෝ☖⧕đᱶ⧁ᙹᯩ݅. ⢽ᅙᱱ᮹ᙹ۵ᱢᨕࠥĥᙹ᮹ᙹ᪡zÑӹ

⍅᧝⦽݅. ݅᧲⦽ᔹ⥭ยႊჶᯕᯩḡอ☖ᔢᱢᮝಽəฝᨱӹ┡ӽ ၵ᪡zᯕł_Ƈŝł_ƇX Ɔň_Ƈ᮹ÏƌâÎ}᳑⧊ᨱᕽƅÞƖßෝ⠪a⦽݅.

ᩍʑᕽ,łƇ᪡ňƇ۵ƖƇ᮹⠪Ɂŝ⢽ᵡ⠙₉ᯕŁƆ۵ᯥ᮹᮹ĥᙹᯕ݅.

ᝅᱽ⦽ĥᔢ┽᮹እᖁ⩶ᖒᮥᅕ݅ᱶ⪶⦹íɝᔍ⪵⦹ʑ᭥⦹ᩍ

݅ᮭŝzᯕ2₉݅⧎᜾ᨱ⪝⧊⧎ᯕ⡍⧉ࡹʑࠥ⦽݅(Khuri et al., 1996).

ĀƅÞƖß á ſâ_{Ƈ á Î}ā^ƌ ^ƀ^Ƈ^Ɩ^Ƈ^â_{Ƈ á Î}ā^ƌ ^Ɓ^Ƈ^Ɩ^Ƈ^Ï^â^{ƌ àÎ}ā_{Ƈ á Î}_{ƈ á Ƈ âÎ}ā^ƌ ^Ƃ^Ƈƈ^Ɩ^Ƈ^Ɩ^ƈ ⁽²⁾

ᯕ౨í ɝᔍ⪵ࡽ 2₉ႊᱶ᜾ ⩶┽᮹ ᮲ݖ໕ ⧉ᙹෝ ᯕᬊ⦹໕

ʑ᳕᮹ᯝĥᝁ഑ࠥჶ(FORM)ᮥᯕᬊ⦹ᩍᝁ഑ᖒ⧕ᕾᯕa܆⦹í

ࡽ݅.

2.2 ண૬ܑ౟ౢ࣑

ݡ⢽ᱢᯙ⇵⇽ჶ(ੱ۵᜽ဍ౩ᯕᖹʑჶ)ᯙ།▭⋕ෝಽ᜽ဍ౩ᯕ ᖹ(Monte Carlo simulation; MCS)ᮡ⪶ශᄡᙹၽᔾኩࠥaᔢݡ ᱢᮝಽԏᦥḩĞᬑᷪ, ❭ƕ⪶ශᯕ᯲ᮡĞᬑᱶ⪶⦽❭ƕ⪶ශ

⇵ᱶᮥ ᭥⧕ᔢݚ⦽ ༉᮹⬀ᙹa ⦥᫵⦹íࡹ໑ əᨱ ঑௝ฯᮡ

᜽eᯕ ⦥᫵⦹í ࡽ݅.

⦽⠙, ᵲ᫵ࠥ⇵⇽ჶ(importance sampling; IS)ᮡ⪶ශᄡᙹ᮹

ၽᔾᯕ❭ƕ໕ᵝ᭥ᨱᕽฯᯕᯝᨕӹࠥಾ⇵⇽(sampling)ᨱᔍᬊ

⦹۵⪶ශၡࠥ⧉ᙹෝ᳑ᱶ⧉ᮝಽ៉༉᮹⬀ᙹၰ᜽eᮥ݉⇶᜽┍

ᙹ ᯩ۵ ႊჶᯕ݅(Bucher et al., 1987).

ᵝᨕḥ ⪶ශᇥ⡍ƎÞƖßෝ w۵ ᯝಉ᮹ ᔹ⥭ƖƇෝ aᱶ⦹໕, Eq. (3)ᨱᕽƄÞƖß᮹ʑݡ⊹᮹⩶᜾ᮡEq. (4)᪡zᯕəᔹ⥭ॅಽᇡ

░ᔑᱶࡽƄÞƖß᮹⠪Ɂᮝಽɝᔍ⪵⧁ᙹᯩ݅. ᩍʑᕽ۵⢽ʑᔢ

⠙᮹ෝ ᭥⦹ᩍ ʑݡ⊹ෝ ݡ⢽⦹ᩍ¢ãƄäෝ ᔍᬊ⦽݅.

¢ãƄä á ƎãƄÞƖßä áõ^{ƄÞƖßƎÞƖßƂƖ} ⁽³⁾

h ć§Îā_{Ƈ á Î}^§ ^ƄÞƖ^Ƈ^ß ⁽⁴⁾

ᵝᨕḥƖᨱᕽƎÞƖß᮹sᮥ⠪a۵⧁ᙹᯩḡอ, ᔑᱶᨱ⦥᫵⦽

ᇥ⡍ಽᇡ░ᔹ⥭ᮥ⇵⇽⦹ʑ۵ᛞḡᦫ݅. ݡᝁᨱᔹ⥭ƖƇෝ⇵⇽⧁

ᯝ໦⢽ᅙᇥ⡍(sampling distribution)௝۵ੱ݅ෙᇥ⡍ƏÞƖßෝ

᯦ࠥ⦽݅.

¢ãƄä áõ^ƄÞƖßćƏÞƖßƎÞƖßƏÞƖßƂƖ h ć§Îā_{Ƈ á Î}^§ ^ćƏÞƖ_Ƈß

ƎÞƖ_Ƈß ƄÞƖ_Ƈß

ý¢ãƄä á ć§Î_{Ƈ á Î}ā^§^Ā^ƕƄÞƖ^Ƈ^{ßì Ā}^{ƕá ć}ƏÞƖ_Ƈß ƎÞƖ_Ƈß

(5)

ᵲ᫵ࠥ⇵⇽ჶ᮹ʑᅙ}ֱᮡƎÞƖß᪡۵݅෕ḡอᮁᔍ⦽ᇥ⡍, ᗭ᭥ƏÞƖßಽᇡ░ᔹ⥭ᮥ⇵⇽⦽݅ᮭ᯹༜ࡽᇥ⡍ᨱᕽ᮹ᔹ⥭ยᮝ ಽ᯦ࠥࡽ⠙᮹(bias)ෝᅕᱶ⦹ʑ᭥⦹ᩍ᨜ᨕḥ᜾ᮥᙹᱶ⦹۵

äᯕ݅. ⦽ᱱᨱᕽƎÞƖßෝ⠪a⧁ᙹᯩ݅Łaᱶ⦹ᩡᮝအಽEq.

(5)ෝ☖⦹ᩍᵝᨕḥƖ_Ƈᨱݡ⦹ᩍ⠙᮹ෝᙹᱶ⦹Ñӹᵲ᫵ࠥaᵲ⊹

Āƕෝ ᱶ⪶⯩ đᱶ⧁ ᙹ ᯩ݅.

ᝅᱽಽƎÞƖßӹƏÞƖß۵᳦᳦እᱶȽ⪵ࡽ(unnormalized) ᷪ, ƎÞƖß á ć³Î ĀƎÞƖß_Ǝ ၰ_{ƏÞƖß á ć}_³

Î ĀƏÞƖßƏ ⩶┽a ࡹ໑, Āƕá ćƏÞƖ_Ƈß

ƎÞƖ_Ƈß á ć³_Ǝ

³_Ə ćĀƏÞƖƇß ĀƎÞƖ_Ƈß

ᩍʑᕽ,

ć³Ə

³_Ǝ

á ć³Ə

õ^{ĀƎÞƖßƂƖ}_áõ^ć_ĀƏÞƖß^ĀƎÞƖß^ƏÞƖß

h ć§Îā_{Ƈ á Î}^§ ^ć_ĀƏÞƖß^ĀƎÞƖß ⁽⁶⁾

(4)

(a) N=1,000, Count=20 (b) N=2,000, Count=20 Fig. 2. Comparison of Errors Between MCS and IS (Nicholas, 2010)

Table 1. Condition of Reliability Analysis

Turbine Capacity 5MW (3-Blades)

Hub height 88m

Foundation

Type Steel monopile

Diameter D=6.0m, t=60mm

Length L=50m

Projection Hs=15m

Ground

Soil Dense sand

Properties ^{Ĺ á Ï×Ɖ§îƋ}

Ð

ŋ á ÐÒŢ

Water depth 15m

Loads

Vertical

Rotor : ÎìÎ××Ɖ§

Nacelle : _{ÏìÑ××Ɖ§}

Tower : ÐìÑÔÒƉ§

Total : _{Ôì×××Ɖ§}

Horizontal

Wind : Îì×××Ɖ§

Wave : _{Îì×××Ɖ§}

Total : Ïì×××Ɖ§

Moment ^{ÕÕì×××Ɖ§_Ƌ}

ᯕŁ, Eq. (6)ᨱᕽ۵ᱶȽ⪵ĥᙹ(normalization factor)ෝᔑᱶ⦹

ʑ ᭥⦹ᩍƏÞƖßಽᇡ░ ᨜ᮡ ᔹ⥭ᮥ ᯕᬊ⦹ᩡ݅. อ᧞, ᵲ᫵ࠥ

aᵲ⊹ෝƕƇಽᰍᱶ᮹⦽݅໕ࢱaḡ⩶┽᮹ɝᔍ⪵ಽӹ┡ԝ

ᙹᯩŁ, ᩍʑᕽEq. (8)ᮡ݉ᙽ⯩Eq. (5)ᨱᕽᮁࠥࡽɝᔍ⊹ᯕ݅.

ý¢ÎãƄä áā_{Ƈ á Î}^§ ^ƕ^Ƈ^ƄÞƖ^Ƈ^{ßì ƕ}^Ƈ^{á ć}

Ɖ á Îā

§ ĀƎÞƖ_ƉßîĀƏÞƖ_Ɖß ĀƎÞƖ_ƇßîĀƏÞƖ_Ƈß

(7)

ý¢ÏãƄä á ć§Îā_{Ƈ á Î}^§ ^ć_ƏÞƖ_Ƈß ƎÞƖ_Ƈß

ƄÞƖƇß (8)

Eq. (7)ᮡƏÞƖß᮹⪶ශᇥ⡍aࢱჩɝᔍ⪵ࡽɝᔍ᜾ᯥᨱᵝ༊⧁

⦥᫵aᯩ݅(ᵝ᫵⧎ᨱᕽ⦽ჩ, əญŁEq. (6)ᨱᕽᵲ᫵ࠥaᵲ⊹ෝ

ᱶȽ⪵⦹ʑ᭥⦹ᩍ⦽ჩ). ᯕ్⦽ɝᔍ⪵۵ƎÞƖßӹƏÞƖßaᱶȽ⪵

ࡽ݅۵ᅕᰆᯕᨧᮥভᵲ᫵⦹݅. ɝᔍ᜾(8)᮹ࢱჩṙ⧎ᮡࢱ ᇥ⡍aᱶȽ⪵ࢉᮥᱥᱽ⦹Ł☖ᔢʑݡ⊹ᨱᕽå^¢ãƄäàý^¢ƇãƄäæ^{á ×}

ᯙ Ğᬑෝ ᱽ᫙⦹Ł۵ ᅙ௹᮹ sŝ zḡ ᦫí ࡽ݅.

đುᱢᮝಽ❭ƕ⪶ශᮡEq. (5)᪡zᯕ❭ƕaၽᔾ⦹۵Ǎe

ԕᨱᕽ⪶ශၡࠥ⧉ᙹෝᱢᇥ⧉ᮝಽ៉᨜ᮥᙹᯩ݅. ᵲ᫵ࠥ⇵⇽ჶ ᨱᕽ۵ƏÞƖßෝ᯦ࠥ⧉ᮝಽ៉❭ƕ⪶ශᮥǍ⦹íࡽ݅. ƏÞƖß۵

❭ƕ໕ᔢ᮹s(ᖅĥᱱ)ᮥ⠪Ɂᮝಽ⦹۵aᔢ᮹⪶ශၡࠥ⧉ᙹᯕ ໑, ᯕ sᮡ FORM ॒᮹ ɝᔍ⧕ჶᮥ ᯕᬊ⦹ᩍ ᨜ᮥ ᙹ ᯩ݅.

əฝᮡMCS᪡IS᮹ᱶၡࠥෝእƱ⦽ᩩಽᕽaಽ⇶ᮡ༉᮹⬀ᙹ, ᖙಽ⇶ᮡ⪶ශᮥӹ┡ԙ݅. ᔢݡᱢᮝಽ༉᮹⬀ᙹ(N)ᨱšĥᨧᯕ

IS᮹᪅₉aᱢíӹ┡ӹ໑, ⇵⇽ᙹ(N)aฯᮥᙹಾᱶࠥa⨆ᔢࢉ

ᮥ ᦭ ᙹ ᯩ݅.

3. ⧕ᔢ⣮ಆ༉י❭ᯝ᮹ᝁ഑ᖒ⧕ᕾ

3.1 ැজ୺Ս

⧕ᔢ᳑Õᨱᕽ⣮ಆ░ኩǍ᳑ྜྷʑⅩ᮹ᦩᱶᖒᮥ⪶ශುᱢᮝಽ

ᇥᕾ⦹ʑ᭥⦹ᩍ↽ɝJonkman et al.(2009)ᯕ⧕ᔢ᜽ᜅ▽ᨱᱢᬊ

⧁༊ᱢᮝಽ}ၽ⦽5MW Ƚ༉᮹⣮ಆ░ኩᱽᬱᮥᯕᬊ⦹ᩡ݅.

}ၽࡽ⣮ಆ░ኩᮡӹᖡ, ት౩ᯕऽ, ┡ᬭၰʑⅩḢĞ᮹ᱽᬱᯕ

ᱽ᜽ࡹᨕ ᯩ݅.

(5)

Fig. 3. Section Layout

Table 2. Characteristics of Random Variables

Random variable Probability distribution

Characteristic

value COV

Horizontal force Normal _{Ïì×××Ɖ§} 0.10

Moment Normal ÕìÕ××Ɖ§_Ƌ 0.10

Elastic modulus of pile Normal ÏÎ× ©ſ 0.05 Angle of internal friction

Normal _{ŋ á ÐÒŢ} 0.15

঑௝ᕽ, Table 1ŝFig. 3ᨱӹ┡ӽၵ᪡zᯕʑⅩᖅĥᨱ⦥᫵⦽

ᩑḢ⦹ᵲᮡ ░ኩǍ᳑ྜྷ᮹ ᱽᬱᮝಽᇡ░ ᔑ⇽⦹ᩡŁ ᙹᝍ, ᙹ⠪

᯲ᬊಆŝ ḡ⊖᳑Õᮡ ᯥ᮹ಽ aᱶ⦹ࡹ ᙹ⠪ ᯲ᬊಆᮡ Bush et al.(2009)ᯕᱢᬊ⦽ᙹ⠪⦹ᵲᮥᯙᬊ⦹ᩡ݅. ✚⯩, ʑⅩḡၹᮡ᳑ၡ

⦽༉௹a⧕ᱡ໕ᮝಽᇡ░35m ᯕᔢ᮹ᝍࠥᨱ᳕ᰍ⦹Łᙹᝍᮡ

15ma ᮁḡࡹ۵ äᮝಽ aᱶ⦹ᩡ݅.

⪶ශುᱢ⧕ᕾᨱᕽ᯲ᬊಆ(ᯱᵲ, ᫙ಆ॒)ŝᱡ⧎᫵ᗭ(ᰍഭ✚ᖒ

॒)᮹ᇩ⪶ᝅᖒᱶప⪵۵ๅᬑᵲ᫵⦹݅. ✚⯩, əᵲᨱᕽࠥ⪶ශᇥ

⡍᪡ᄡ࠺ᖒᮡ⧕ᕾđŝᨱᵝ᫵⦹íᩢ⨆ᮥၙ⊹۵ᯙᯱᯕ݅. ⪶ශ

ುᱢ⧕ᕾᨱᱢᬊ⦽⪶ශᄡᙹॅŝə✚ᖒᮥ Table 2ᨱӹ┡ԕᨩ݅.

ᅙᩑǍᨱᕽ۵ᩍ్aḡᖅĥᄡᙹaᬕߑ⦹ᵲᮝಽᕽᙹ⠪ಆŝ

༉ູ✙, ᱡ⧎᫵ᗭಽᕽ ❭ᯝ᮹ ┥ᖒĥᙹ᪡ ḡၹ᮹ ԕᇡษₑbᮥ

⪶ශᄡᙹಽ≉ɪ⦹ᩡ݅. ༉ु⪶ශᄡᙹ᮹ᇥ⡍۵ᱶȽ(normal)ᇥ

⡍ෝ঑෕ŁTable 2ᨱӹ┡ӽၵ᪡zᯕ5ⴇ15%᮹ᇩ⪶ᝅᖒᮥ

aḡ۵ äᮝಽ aᱶ⦹ᩡ݅.

3.2 ਑߲নැজր࠻Թ࣡৤ंজ

༉י❭ᯝ᮹ࢱᇡᙹ⠪ᄡ᭥ᨱݡ⦽❭ƕ⪶ශੱ۵ᝁ഑ࠥḡᙹෝ

ĥᔑ⦹ʑ᭥⦹ᩍ᮲ݖ໕ʑჶ(RSM)ŝᵲ᫵ࠥ⇵⇽ჶ(IS)ᮥᯕᬊ

⦹ᩡ݅. IS۵᮲ݖ໕ᵝᄡᨱᕽ10,000}᮹ӽᙹෝᔾᖒ⦹ᩍ⦽ĥᔢ

┽⧉ᙹෝĥᔑ⦽⬥❭ƕ⪶ශᮥᔑᱶ⦹ᩡŁĥᔑࡽ⦽ĥᔢ┽⧉ᙹ

sॅ᮹ ᄡ࠺ᖒᯕ 0.01% ᯕԕa ࢁ ভʭḡ ၹᅖ⦹ᩍ ᱶၡࠥෝ

⪶ᅕ⦹ᩡ݅.

ᝁ഑ᖒ ⧕ᕾᮡ ⦽ǎ⧕᧲ŝ⦺ʑᚁᬱᨱᕽ }ၽ⦽ ᝁ഑ᖒ ᖅĥ

⥥ಽəఉHSRBD ver3.1(2013)ᮥᯕᬊ⦹ᩡ݅. HSRBD(Harbor Structure Reliability Based Design)ᮡp-y ༉ߙᮥᯕᬊ⦹ᩍั૾

᮹ᝁ഑ᖒᖅĥaa܆⦽⥥ಽəఉᮝಽᕽ, ั૾ᯕ᫙ᨱࠥႊ❭ᱽ᪡

ᦩᄞ, ⪙ᦩ॒⧎อǍ᳑ྜྷᮥ⨩ᬊ᮲ಆၰᝁ഑ᖒʑჶᮥᯕᬊ⦹ᩍ

⧕ᕾ⧁ᙹᯩ۵༉ऩᮥw⇵Łᯩ݅. ᝁ഑ᖒ⧕ᕾʑ܆ᮡᇡᇥᦩᱥĥ ᙹჶ(౩ᄉ1)ᮝಽᇡ░FORM, RSM᮹౩ᄉ2 ၰMCS ၰISෝ

⡍⧉⦽ ౩ᄉ 3ʭḡ ݅᧲⦹í ⧕ᕾᯕ a܆⦹݅.

ᅙᩑǍᨱᕽ݅൉۵༉י❭ᯝǍ᳑ྜྷᮡ༉௹ḡၹᨱᖅ⊹ࡹ۵

❭ᯝʑⅩಽᕽaᔢŁᱶ᜾ԕḡ۵॒ᇥ⡍ ᜅ⥥ย᜾⧕ᕾ༉ߙᮥ

ᯕᬊ⦹အಽp-y łᖁᮥᯕᬊ⦹ᩍᄡ᭥᪡⫭ᱥbᮥĥᔑ⦹íࡽ݅.

঑௝ᕽ, ᩍʑᕽ۵ ᔍḩ☁ ḡၹᨱᕽ p-y ༉ߙಽ ฯᯕ ᔍᬊࡹ۵

API(2005) ႊჶŝᝮłᖁ༉ߙ(Dewaikar et al., 2006)ᮥᱢᬊ⦹

ᩡ݅.

⨩ᬊ᮲ಆᖅĥჶᨱᕽ❭ᯝࢱᇡ᮹ᙹ⠪ᄡ᭥᪡⫭ᱥbᨱݡ⦽

ᦩᱶᩍᇡ۵bb⨩ᬊᄡ᭥ၰ⨩ᬊ⫭ᱥbʑᵡŝĥᔑࡽᙹ⠪ᄡ᭥

ၰ⫭ᱥbᮥእƱ⦹ᩍ❱݉⦽݅. ঑௝ᕽ, ⦽ĥᔢ┽⧉ᙹ۵݅ᮭŝ

zᯕᱶ᮹⧁ᙹᯩ݅. ᩍʑᕽ,ĺ᪡ľ۵bb᫙ಆᨱ᮹⧕

ၽᔾࡹ۵ ᙹ⠪ᄡ᭥᪡ ⫭ᱥbᯕŁĺ_ſ᪡ľ_ſ۵ ⨩ᬊ ᙹ⠪ᄡ᭥ ၰ

⫭ᱥbᮝಽᕽŝÑᩑǍᔍಡ(DNV, 2007; Kuo et al., 2008)ෝ

ₙŁ⦹ᩍĺ_ſá Ó×ƋƋ, _ľ_ſá ×íÐŢಽ ᖅᱶ⦹ᩡ݅.

ƅ_Îá ĺ_ſà ĺ (9)

ƅ_Ïá ľ_ſà ľ (10)

᮲ݖ໕ʑჶᮥᱢᬊ⦹ʑ᭥⦹ᩍEqs. (9) and (10)᮹⦽ĥᔢ┽⧉

ᙹෝ᮲ݖ໕⧉ᙹಽᄡ⪹⦹໕݅ᮭŝz݅. ᩍʑᕽ,ŋ_ƑſƌƂ۵༉௹᮹

ԕᇡษₑb, Ǝ۵❭ᯝ᮹┥ᖒĥᙹᯕŁƌᮡǍ᳑⧕ᕾᮥ☖⦹ᩍ

⫭ȡᇥᕾᮝಽ Ǎ⧕ḡ۵ ĥᙹᯕ݅.

ƅ_ÎÞĺ_ſì ĺß á ĺ_ſà ĺÞŋ_ƑſƌƂì _Ǝß

á _×â_Îŋ_ƑſƌƂâ_Ï_Ǝâ_Ðŋ_ƑſƌƂ^Ï â_Ñ_Ǝ^Ïâ_Òŋ_ƑſƌƂ_Ǝ

(11)

(6)

Table 3. Comparison of Reliability Index for Reliability Analysis Methods and p-y Models

Horizontal displacement of

head Rotational angle of Head

RSM IS RSM IS

API(2005) 2.1585 2.1648 2.9412 2.9403 Hyperbolic 1.8319 1.8373 2.5796 2.5796

Fig. 4. Variation of Probability of Failure on Allowable Horizontal Fig. 5. Variation of Probability of Failure on Allowable Rotation ƅÏÞľ_ſì ľß á ľ_ſà ľÞŋ_ƑſƌƂì _Ǝß

á _Óâ_Ôŋ_ƑſƌƂâ_Õ_Ǝâ_Öŋ_ƑſƌƂ^Ï â_Î×_Ǝ^Ïâ_ÎÎŋ_ƑſƌƂ_Ǝ

(12)

᮲ݖ໕ʑჶ(RSM)ŝᵲ᫵ࠥ⇵⇽ჶ(IS)ᮥᯕᬊ⦽⧕ᕾđŝෝ

Table 3ᨱእƱ⦹ᩡ݅. ࢱᇡᙹ⠪ᄡ᭥(ƅ_Î)a⫭ᱥb(ƅ_Ï)❭ƕ༉ऽ ᨱእ⦹ᩍᝁ഑ࠥḡᙹa᯲íᔑᱶࡹᨕḡ႑❭ƕ༉ऽᯙäᮝಽ

ӹ┡ԍ݅. API(2005) ʑᵡᨱᱽ᜽ࡽp-y ⧉ᙹෝᯕᬊ⦽đŝ᪡

እƱ⧁ভᝮłᖁ(hyperbolic) ⧉ᙹෝᯕᬊ⦽Ğᬑᝁ഑ࠥḡᙹ۵

14ⴇ18% ⡍ᯙ✙aపԏíᔑᱶࡹᨩŁᯕ۵Ǎᖒ᜾᮹₉ᯕᨱᕽ

ʑᯙ⦽݅. RSMŝ ISෝ ᯕᬊ⦽ ᝁ഑ࠥḡᙹ۵ ᪅₉a ᧞ 0.3%

ᯕԕಽÑ᮹ᯝ⊹⦹۵đŝෝᅕᩡ݅. ᯕ۵ISෝᯕᬊ⦽⇵⇽᜽

ᯕၙRSMᨱᕽɝᔍ⪵ࡽ❭ƕᱱᵝᄡᨱᕽsॅᮥ⇵⇽⦹ʑভྙᯙ

äᮝಽ ❱݉ࡽ݅.

Eqs. (9) and (10)᮹⦽ĥᔢ┽⧉ᙹᨱӹ┡ԍॐᯕ⨩ᬊᙹ⠪ᄡ᭥᪡

⨩ᬊ⫭ᱥbᯕbb᮹❭ƕ༉ऽᨱᕽᱡ⧎ᨱ⧕ݚ⦹အಽ⨩ᬊᄡ᭥

ၰ⫭ᱥbʑᵡ᮹ᖅᱶᨱ঑௝❭ƕ⪶ශᮡݍ௝ḡíࡽ݅. ঑௝ᕽ, ᯕॅᮥᄡ⪵᜽┅໑⧕ᕾ⧉ᮝಽ៉ĥᔑࡽ❭ƕ⪶ශ᮹ᄡ⪵ෝšₑ

⦹ᩡ݅. Fig. 4ᨱӹ┡ӽၵ᪡zᯕ⨩ᬊᄡ᭥a15mmᨱᕽ100mm ʭḡᄡ⪵⧁ভ❭ƕ⪶ශᮡÑ᮹ݡᙹᱢ(logarithmic)ᮝಽqᗭ⦹

۵äᮥ᦭ᙹᯩ݅. ǎԕ᮹ั૾ᖅĥ᜽ᯕᬊࡹ۵Ƚᱶaᬕߑ

❭ᯝḢĞ᮹ 1%ᨱ ⧕ݚ⦹۵ 60mmᨱᕽ ❭ƕ⪶ශᮡ ᧞ 1.5%ᯙ

ၹ໕, ↽ᗭ ʑᵡᄡ᭥ᯙ 15mmಽ ᖅᱶ⦽ Ğᬑ᮹ ❭ƕ⪶ශᮡ ᧞

60%ಽᕽๅᬑⓑäᮥ᦭ᙹᯩ݅. Fig. 5۵⨩ᬊ⫭ᱥbᮥ0.2ⴇ 0.6°ʭḡ᮹ ჵ᭥ಽ ᖅᱶ⧁ ভ᮹ ❭ƕ⪶ශಽᕽ ᩎ᜽ ݡᙹᱢᮝಽ

qᗭ⦹ӹəჵ᭥۵Î×^àÓg Î×^Î%ಽᙹ⠪ᄡ᭥❭ƕᨱእ⦹ᩍๅᬑ

᯲ᮡ ჵ᭥ᨱᕽ ᄡ⪵⦹ᩡ݅.

༉י❭ᯝ᮹ḢĞᮡᙹ⠪ḡḡಆᐱᦥܩ௝ᄡ᭥qᗭ⬉ŝ᪡Ğᱽ ᖒᨱࠥၝq⦽᫵ᗭᯕအಽ↽ᱢᖅĥᨱᕽ❭ᯝ᮹ ḢĞᮡᵝ᫵⦽

Łಅᔍ⧎ᯕ݅. ঑௝ᕽ, ༉י❭ᯝ᮹ḢĞᮥᄡ⪵᜽┅໑⧕ᕾ⦹ᩍ

❭ƕ⪶ශᄡ⪵ෝšₑ⦹ᩡ݅. Fig. 6ᨱӹ┡ӽၵ᪡zᯕḢĞᯕ

᷾a⧁ᙹಾ❭ƕ⪶ශᯕqᗭ⦹໑əqᗭ⡎ᮡ⍅Კḡ႑❭ƕ༉ऽ ᯙᙹ⠪ᄡ᭥᮹Ğᬑ7.0mᇡ░۵ḢĞᮥ᷾a᜽⍽ࠥ↽ݡ❭ƕ⪶ශ ᮹₉ᯕ۵0.27% ⡍ᯙ✙ᯕ⦹ಽӹ┡ԉᮝಽ៉ᄡ᭥qᗭ⬉ŝa

ᱢᨕḡ۵äᮝಽӹ┡ԍ݅. ᯕ۵༉௹ḡၹᨱᕽ༉י❭ᯝᯕᯝᱶ⦽

ḢĞᯕᔢ⪶ᅕࡹ໕ࢱᇡ᮹᮲ಆᯕᱱ₉⦹ᇡಽᱥᯕࡹ໕ᕽӹ┡ӹ ۵⩥ᔢᮝಽ❱݉ࡽ݅. ᦥᬙ్, ⫭ᱥb᮹Ğᬑ۵ḢĞ᷾aᨱ঑௝

❭ƕ⪶ශᯕɪĊ⦹í᯲ᦥḱᮝಽ៉ᔢݡᱢᮝಽḢĞᄡ⪵ᨱ঑௝

ၝq⧉ᮥ ᦭ ᙹ ᯩ݅.

༉י❭ᯝ᮹ ʙᯕ۵ ʑၹᦵ⊖᮹ ᝍࠥ, ḡ⊖ᇥ⡍᪡ ᙹᝍ ॒ᨱ

ᩢ⨆ᮥၼᮝ໑Ğᱽᖒᨱⓑᩢ⨆ᮥၙ⊽݅. ঑௝ᕽ, ❭ᯝ᮹ʙᯕᨱ

঑௝❭ƕ⪶ශ᮹ᄡ⪵ෝšₑ⦹ᩡ݅. Fig. 7ᨱӹ┡ԕᨩॐᯕ❭ᯝ᮹

ʙᯕa ᷾a⧉ᨱ ঑௝ ❭ƕ⪶ශᮡ qᗭ⦹Ł ə qᗭ⡎ᮡ ᱱ₉

᯲ᦥḥ݅. ࢱᇡᙹ⠪ᄡ᭥᪡⫭ᱥb❭ƕ༉ࢱ❭ᯝʙᯕ60mᇡ░

❭ƕ⪶ශ᮹qᗭ⡎ᮡ ๅᬑ ᯲ᦥᲙə ₉ᯕ۵ ᧞0.07% ᯕ⦹ಽ

ӹ┡ӽ݅. ᷪ, ❭ᯝʙᯕ60mᇡ░۵ʙᯕa᷾a⦹ᩍࠥᄡ᭥qᗭ⬉

ŝ۵ ၙၙ⧉ᮥ ᦭ ᙹ ᯩ݅.

☁ḩᱶᙹ᮹ᇩ⪶ᝅᖒᮡእƱᱢⓍӹ༉௹᮹ԕᇡษₑbᨱݡ⦽

ᄡ࠺ᖒᮡᯝၹᱢᮝಽ10% ԕ᫙ᯙäᮝಽ᦭ಅᲙᯩ݅. ԕᇡษₑb ᮹ᄡ࠺ᖒᨱ঑ෙၝqࠥෝ❭ᦦ⦹ʑ᭥⦹ᩍᄡ࠺ĥᙹ(COV)ෝ

(7)

Fig. 6. Variation of Probability of Failure on Monopile Diameter

Fig. 7. Variation of Probability of Failure with Varying Mono-pile Length

Fig. 8. Variation of Reliability Index on Uncertainty of Internal Friction Angle

qᗭ᜽┅໑⧕ᕾ⦹ᩍəđŝෝFig. 8ᨱӹ┡ԕᨩ݅. ݅ෙ⧕ᕾ᳑

Õᮡ࠺ᯝ⦽ᔢ┽ᨱᕽCOVෝݚⅩ15%ᨱᕽ10%ಽqᗭ⦹ᩍ

⧕ᕾ⦽đŝ, ᝁ഑ࠥḡᙹ(ⱖ)۵᧞0.35% ⡍ᯙ✙᷾a⦹۵ߑəⅅ

݅. ၹ໕10% ᯕ⦹᮹COV ჵ᭥ᨱᕽ۵ๅᬑ݅ෙ᧲ᔢᮥӹ┡ԕᨩ

݅. ᷪ, ԕᇡษₑb᮹COV 8%ᨱᕽᝁ഑ࠥḡᙹ62.6% ⡍ᯙ✙

᷾a, COV 6%ᨱᕽ۵72.5% ⡍ᯙ✙᷾a⦹۵॒ԕᇡษₑb᮹

COV 10% ᯕԕᨱᕽ۵ ᝁ഑ࠥḡᙹ ᔢ᜚ ⡎ᯕ ๅᬑ ⓑ äᮝಽ

ӹ┡ԍ݅. ᯕ۵༉௹ḡၹᨱ༉י❭ᯝᯕᖅ⊹ࡹ۵Ğᬑԕᇡษₑb ᮹ᄡ࠺ᖒᙹᵡᯕ❭ƕ⪶ශŝŖᔍእᨱⓑᩢ⨆᫵ᯙᯥᮥӹ┡ԕ۵

äᯕ݅.

3.3 คࠔ࣡৤ଭࢢԮܑंজ

2₉᜾⩶┽ಽɝᔍ⪵ࡽ᮲ݖ໕⧉ᙹෝaḡŁFORMᨱ᮹⧕

⧕ᕾ⦹۵ŝᱶᨱᕽᝁ഑ࠥḡᙹ᪡ၝqࠥḡᙹ(sensitivity factor)ෝ

᨜ᮥᙹᯩ݅. Eq. (13)᮹ᝁ഑ࠥḡᙹ(reliability index, ĸ)᪡b

⪶ශᄡᙹ᮹ၝqࠥḡᙹ(ķćĈ±)᮹šĥಽᇡ░ࢱᄡᙹ᮹ၹᅖĥᔑᮥ

☖⦹ᩍᯝᱶ⦽sᨱᙹಕ⦹۵ĸ᪡ķćĈ±ෝđᱶ⦽݅(Yoon et al., 2010). ᜾ᨱᕽ^ćĈ±^Ý۵☖ĥᱢᮝಽࠦพᯙ⪶ශᄡᙹ, ^ćĈ±۵⢽ᵡᱶȽ ᇥ⡍ಽᖁ⩶ᄡ⪹ࡽ⪶ශᄡᙹ, ³۵⦽ĥᔢ┽⧉ᙹෝ᮹ၙ⦽݅. Eq.

(13)ᮡ⪶ශᄡᙹᔍᯕᨱᕽಽᔢšᖒᯕᨧᮥভ᮹šĥᯕ໑, ķćĈ±۵

⢽ᵡ⪵ࡽŖeᔢ᮹b⪶ශᄡᙹ⇶ᨱᕽ ᝁ഑ࠥḡᙹ᮹ႊ⨆ᩍ⩥

(direction cosine)ᮥ ᮹ၙ⦽݅.

ķćĈ±á ÞćŞćĈŞ³ ç± ćĈ

ੱ⦽, ༉ु⪶ශᄡᙹ᮹ķćĈ±۵Eq. (14)᮹šĥෝอ᳒⦹ࠥಾ

đᱶ⧕᧝ ⦽݅.

ā^Þķ^ćĈ^±^ß^Ï^{á Î} ⁽¹⁴⁾

ၝqࠥḡᙹ۵b⪶ශᄡᙹa❭ƕ⪶ශᨱၙ⊹۵ʑᩍࠥෝ᮹ၙ

⦹໑, ᯝၹᱢᮝಽ ᫙ಆ᮹ ᄡᙹᨱ ݡ⦹ᩍ ᧲(+)᮹ sᮥ, ᱡ⧎᮹

ᄡᙹᨱ ݡ⦹ᩍ ᮭ(-)᮹ sᮥ ӹ┡ԙ݅.

Fig. 9ᨱӹ┡ԍॐᯕᅙᩑǍᨱᕽ⪶ශᄡᙹಽ≉ɪ⦽ᖙaḡ

ᄡᙹaᬕߑ⮺᮹ԕᇡษₑbᨱݡ⦽ၝqࠥaḡ႑ᱢᯙäᮝಽ

ӹ┡ԍᮝ໑݅ᮭᮝಽ᫙ಆ(ᙹ⠪ಆၰ༉ູ✙)ŝ❭ᯝ᮹┥ᖒĥᙹ

ᙽᯕᨩ݅. ᯕ۵⮺᮹ԕᇡษₑbᯕ❭ƕ⪶ශᨱၙ⊹۵ᩢ⨆ᯕaᰆ

Ⓧအಽᖅĥ᜽ḡၹ᳑ᔍၰ᜽⨹᮹ᱶࠥෝ׳ᩍᇩ⪶ᝅᖒᮥ↽ᗭ⪵

⦹ᩍ᧝ Ğᱽᖒᮥ ᱽŁ⧁ ᙹ ᯩᮭᮥ ᮹ၙ⦹ʑࠥ ⦽݅.

b⪶ශᄡᙹ᮹ᄡ࠺ĥᙹෝᄡ⪵᜽┅໑ၝqࠥḡᙹ(ķ)᮹ᄡ⪵ෝ

šₑ⦽đŝFig. 10ᨱӹ┡ԍॐᯕԕᇡษₑbᨱݡ⦽ၝqࠥḡᙹ

(8)

Fig. 9. Sensitivity of Random Variables

Fig. 10. Sensitivity on Variation of COV

۵1ᨱaʭᬕsᮝಽӹ┡ӹⓑᄡ⪵aᨧ۵äᮝಽӹ┡ԍ݅.

ӹນḡ⪶ශᄡᙹ᮹Ğᬑ۵ᄡ࠺ᖒᯕ᯲ᦥḩᙹಾᱡ⧎šಉ⪶ශᄡ ᙹ۵0ᮝಽᇡ░1ಽ, ⦹ᵲšಉ⪶ශᄡᙹ۵0ᮝಽᇡ░-1ಽɝᱲ⧕

e݅. ᯕ۵⪶ශᄡᙹ᮹ᇩ⪶ᝅᖒᯕⓕᙹಾ❭ƕ⪶ශᨱၙ⊹۵ᩢ⨆

ᯕ ⓝᮥ ᮹ၙ⦽݅.

4. đು

ᅙםྙᨱᕽ۵ǎ᫙ᨱᕽᖅĥၰ᜽Ŗࡽ⧕ᔢ⣮ಆၽᱥ༉ߙᮥ

ᯕᬊ⦹ᩍ༉י❭ᯝ⦹ᇡǍ᳑a༉௹ḡၹᨱᖅ⊹ࡹ۵Ğᬑᨱ⪶ශ

ುᱢ⧕ᕾᮥ☖⦹ᩍʑⅩ᮹Ñ࠺ᮥ❭ᦦ⦹Łəၝqࠥෝᇥᕾ⦹ᩡ

݅. ᩑǍđŝ۵ ݅ᮭŝ z݅.

(1) ⨩ᬊ᮲ಆᖅĥჶᨱᕽ Ǎ᳑ྜྷ᮹ᦩᱶᖒ ❱݉ʑᵡᯙ ᙹ⠪ᄡ᭥

ၰ⫭ᱥbᨱݡ⧕⨩ᬊ⊹ෝ᷾a᜽┅۵Ğᬑᨱ༉י❭ᯝʑⅩ

᮹❭ƕ⪶ශᮡݡᙹᱢᮝಽqᗭ⦹ᩡ݅. ǎԕั૾ᖅĥȽᱶᯙ

❭ᯝḢĞ(D=6m)᮹1%ෝ⨩ᬊᙹ⠪ᄡ᭥(60mm)ಽᱢᬊ⦹۵

Ğᬑ❭ᯝ᮹❭ƕ⪶ශᮡ1.5%ᯕŁ↽ᗭʑᵡᯙ15mmᨱݡ⧕

ᕽ۵60%ಽᕽə₉ᯕaⓍအಽ⧕ᔢ⣮ಆ݉ḡᨱᱢᬊ⦹ʑ

᭥⦽❭ᯝ᮹ᙹ⠪ᄡ᭥ၰ⫭ᱥbᨱݡ⦽⨩ᬊʑᵡ᮹ᱶพᯕ

᜽ɪ⦽ ŝᱽᯙ äᮝಽ ⠪aࡹᨩ݅.

(2) ༉י❭ᯝ᮹ḢĞᯕ⍅ḡ໕ᙹ⠪ᄡ᭥ၰ⫭ᱥbᨱݡ⦽❭ƕ⪶

ශᮡqᗭ⦹ӹḢĞᯕ7.0m ᯕᔢ᮹Ğᬑᱱ₉ᙹಕ⦹ᩍ❭ƕ⪶

ශ᮹ᱡq⬉ŝ۵ၙၙ⦹ᩡ݅. ᯕ۵༉௹ḡၹᨱᕽ༉י❭ᯝᯕ

ᯝᱶ⦽ḢĞᯕᔢ⪶ᅕࡹ໕ࢱᇡ᮹᮲ಆᯕᱱ₉⦹ᇡಽᱥᯕࡹ

໕ᕽӹ┡ӹ۵⩥ᔢᮝಽ❱݉ࡽ݅. ᦥᬙ్❭ᯝḢĞᄡ⪵ᨱ

ݡ⦽ᩢ⨆ᮡ❭ᯝࢱᇡ᮹ᙹ⠪ᄡ᭥ᨱእ⦹ᩍ⫭ᱥbᯕᅕ݅

ⓑ äᮝಽ ӹ┡ԍᮝ໑ ᯕෝ ↽ᱢᖅĥᨱ ⪽ᬊ⧁ ᙹ ᯩ݅.

(3) ⧕ᱡ໕ᮝಽᇡ░ʑၹᦵ⊖᮹ᝍࠥaʫᨕ❭ᯝᯕ༉௹ḡၹᨱ

ɝ᯦ࡹ۵ษₑั૾ᯙĞᬑ❭ᯝʙᯕa᷾a⧉ᨱ঑௝ᙹ⠪ᄡ᭥

ᨱݡ⦽❭ƕ⪶ශᮡqᗭ⦹ӹəqᗭ⡎ᮡ᯲ᦥḡ໑, ❭ᯝʙᯕ a ᯝᱶ ɝ᯦ʫᯕ ᯕᔢᯕ ࡹ۵ ᳑Õ, ᷪ 60m ᯕᔢᯕ ࡹ۵

Ğᬑ ᙹ⠪ᄡ᭥᮹ qᗭ⬉ŝ۵ ᯲í ⠪aࡹᨩ݅.

(4) FORMᮥᯕᬊ⦽ၝqࠥᇥᕾđŝ, ᄡ࠺ᖒᯕⓑᔍḩ☁ḡၹ᮹

ᅙᔍಡᨱᕽ۵⮺᮹ԕᇡษₑbᯕ❭ᯝ᮹Ñ࠺ᨱaᰆⓑᩢ⨆

ᮥ ၙ⊹۵ äᮝಽ ӹ┡ԍ݅. ঑௝ᕽ, ᇩ⪶ᝅᖒᯕ ⓕ äᮝಽ

ᩩ⊂ࡹ۵ʑⅩḡၹᨱᕽ۵ᱶၡ⦽ḡၹ᳑ᔍᐱᦥܩ௝ᄡ࠺ᖒ

ᇥᕾᯕĞᱽᖒŝᦩᱶᖒᮥ↽ᱢ⪵⦹۵⊂໕ᨱᕽๅᬑᵲ᫵⦽

äᮝಽ ❱݉ࡽ݅.

qᔍ᮹ɡ

ᅙםྙᮡ⦽ǎ⧕᧲ŝ⦺ʑᚁᬱᨱᕽᙹ⧪ᵲᯙʑšᩎప₞᮹ŝ ᱽ“⧕ᔢ⣮ಆḡḡǍ᳑ÕᖅʑᚁᩑǍ, PE99122”᪡ᔑᨦ☖ᔢᯱᬱ ᇡaḡᬱ⦹Ł⦽ǎᨱթḡʑᚁ⠪aᬱᯕšญ⦹۵ǎ₦ŝᱽ“⧕ᔢ

⣮ಆᱥᬊᝁ഑ᖒᖅĥ⥥ಽəఉ}ၽ, PN65510”᮹ᰍᱶᱢḡᬱᮝ ಽ a܆⧩ᮭᨱ qᔍऽพܩ݅.

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Jonkman, J., Butterfield, S., Larsen, T. J., Passon, P., Camp, T., Nichols, J., Azcona, J. and Martinez, A. (2007). “Offshore code comparison collaboration within IEA wind annex XXIII: PhaseII results regarding monopile foundation modeling.” 2007 European

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Khuri, A. I. and Cornell, J. A. (1996). Response surfaces designs and analyses, second edition, Marcel Dekker.

KIOST (2013). HSRBD ver.3.1 harbour structure reliability based design (in Korean).

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