op ile , ▁a ▁single ▁large - d iam eter ▁( 4 ▁to ▁ 6 ▁metres ) ▁tub ular ▁steel ▁p ile ▁driven ▁to ▁a ▁depth ▁of ▁ 5 - 6 ▁times ▁the ▁diameter ▁of ▁the ▁p ile ▁into ▁the ▁se ab ed . ▁The ▁coh es ion ▁of ▁the ▁soil , ▁and ▁fr iction ▁between ▁the ▁p ile ▁and ▁the ▁soil ▁provide ▁the ▁necessary ▁struct ural ▁support ▁for ▁the ▁wind ▁tur bine . ▁ ▁In ▁on sh ore ▁tur b ines ▁the ▁most ▁common ▁type ▁of ▁foundation ▁is ▁a ▁gravity ▁foundation , ▁where ▁a ▁large ▁mass ▁of ▁concrete ▁spread ▁out ▁over ▁a ▁large ▁area ▁is ▁used ▁to ▁resist ▁the ▁tur bine ▁loads . ▁Wind ▁tur bine ▁size ▁& ▁type , ▁wind ▁conditions ▁and ▁soil ▁conditions ▁at ▁the ▁site ▁are ▁all ▁determ ining ▁factors ▁in ▁the ▁design ▁of ▁the ▁foundation . ▁ ▁Cost s ▁▁ ▁The ▁modern ▁wind ▁tur bine ▁is ▁a ▁complex ▁and ▁integrated ▁system . ▁Struct ural ▁elements ▁compr ise ▁the ▁majority ▁of ▁the ▁weight ▁and ▁cost . ▁ ▁All ▁parts ▁of ▁the ▁structure ▁must ▁be ▁in exp ensive , ▁light weight , ▁dur able , ▁and ▁manufact urable , ▁under ▁variable ▁loading ▁and ▁environmental ▁conditions . ▁Tur bine ▁systems ▁that ▁have ▁fewer ▁fail ures , ▁require ▁less ▁maintenance , ▁are ▁l ighter ▁and ▁last ▁longer ▁will ▁lead ▁to ▁reducing ▁the ▁cost ▁of ▁wind ▁energy . ▁ ▁One ▁way ▁to ▁achieve ▁this ▁is ▁to ▁implement ▁well - document ed , ▁valid ated ▁analysis ▁codes , ▁according ▁to ▁a ▁ 2 0