Strukturna analiza rampe za polaganje cjevovoda na morsko dno

Gunjača, Darko (2013) Strukturna analiza rampe za polaganje cjevovoda na morsko dno. = Professional thesis , Sveučilište u Zagrebu, Fakultet strojarstva i brodogradnje, UNSPECIFIED. Mentor: Rudan, Smiljko.

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Abstract (Croatian)

Rampe za polaganje cjevovoda na morsko dno složene su rešetkaste konstrukcije izložene značajnim opterećenjima prilikom rada. Ta opterećenja, a uz njih i projektni zahtjevi, rastu s povećanjem dubine mora na kojoj se cjevovod polaže. Brod Pieter Schelte, u vlasništvu tvrtke Allseas, bit će dovršen 2014. godine i moći će cjevovod polagati na dubinama do 3500 m. U okviru ovog specijalističkog rada provedena je strukturna analiza rampe tog broda, na osnovi nacrta koje je ustupilo brodogradilište \NMC iz \Nizozemske. Polaganje cjevovoda tim brodom odvija se S-lay postupkom. Stoga je na početku rada opisan taj postupak, a zatim je analizirana ravnoteža sila koje se pri takvom polaganju pojavljuje. Pravila klasifikacijskih društava opisuju značajke koje takva konstrukcija mora posjedovati. U ovom radu korištena su pravila društva Det \Norske Veritas za analizu okolišnih uvjeta i opterećenja (D\NV-RP-C205) i karakteristika cjevovoda (D\NV-OS-F101), kao i API pravila za projektiranje nepomičnih odobalnih konstrukcija (API-RP2A). Za potrebne strukturne analize generiran je globalni model rampe koji je opterećen sukladno scenariju polaganja cjevovoda na najveću dubinu. \Na osnovi rezultata određena su područja najvećih naprezanja i kritični strukturni detalji. Oni su dalje analizirani tehnikom podmodela prve razine ljuskastim konačnim elementima i druge razine, volumnim konačnim elementima, do razine zavara. \Na osnovi pravila za proračun zamora čeličnih odobalnih konstrukcija (D\NV-RP-C203) provedena je analiza žarišnih naprezanja i faktora koncentracije naprezanja odabranog strukturnog detalja. Konačno, učinjena je analiza zamornog vijeka strukturnog detalja izvrgnutog najvećem opterećenju, tijekom pretpostavljenog radnog vijeka rampe i broda od 30 godina.

Abstract

Stingers for pipe laying on seabed are complex pipe structures exposed to significant loads during pipe laying operation. These loads, and with them design requirements, increase with depth of sea where the pipeline is laying. Pieter Schelte vessel, owned by Allseas, will be completed in 2014 year and will be able to lay the pipeline at sea depths up to 3500 m. In this thesis structural analysis of ship stinger was conducted according to drafts provided by NMC, shipbuilding company from Netherlands. Pipe laying is performed with S-lay pipe laying method. Therefore, at the beginning of this thesis S-lay method was described, and after that analysis of balance forces was made. Force balance occurs during pipe laying procedure. Rules of classification societies describe features that such structures must possess. In this thesis, rules of society Det Norske Veritas were used for analysis of environmental conditions and loads (DNV-RP-C205), and for characteristics of pipeline (DNV-OS-F101). Also API rules were used for designing fixed offshore structures (API RP2A). Global stinger model was made which was subjected to loads defined according to pipeline laying scenario at maximum depth. Based on results, areas of greatest stress and critical structural details were determined. This detail was further analyzed by submodel technique, first level submodel was made with shell finite elements and second level submodel was made with volume finite elements including weld geometry. Based on the rules for fatigue calculation of steel offshore structures (DNV-RP-C203), an analysis of hot spot stress and stress concentration factor was performed for selected structural detail. Finally, fatigue life analysis was performed for that structural details subjected to maximum loading, during stringer assumed life expectancy of 30 years.

Item Type: Thesis (Professional thesis)
Uncontrolled Keywords: rampa za polaganje cjevovoda; S–lay postupak polaganja cjevovoda; strukturni detalji spoja cijevi; zamor materijala; nazivna naprezanja; žarišna naprezanja; faktor koncentracije naprezanja; izvijanje
Keywords (Croatian): stinger; S–lay pipe laying; structural details of pipe connections; fatigue; nominal stress; hot- spot stress; stress concentration factor – SCF; buckling
Divisions: 600 Department of Naval Engineering and Marine Technology > 620 Chair of Marine Structures Design
Date Deposited: 22 Sep 2014 18:00
Last Modified: 16 Oct 2015 12:51
URI: http://repozitorij.fsb.hr/id/eprint/2738

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