Analisis Tegangan Rack And Pinion System Pada Jack-Up Platform Akibat Beban Lingkungan Pada Fase Penurunan Kaki

Ramadhan, Iman Sinergi (2026) Analisis Tegangan Rack And Pinion System Pada Jack-Up Platform Akibat Beban Lingkungan Pada Fase Penurunan Kaki. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Fase penurunan kaki (leg lowering) pada Jack-Up Platform merupakan kondisi kritis di mana struktur rentan terhadap beban lingkungan berupa angin, gelombang, dan arus. Penelitian ini bertujuan mengevaluasi respon gerak hull serta tegangan pada sistem rack and pinion selama
fase tersebut di perairan Selat Madura. Metodologi mengintegrasikan tiga tahap analisis: analisis respon gerak menggunakan MOSES, analisis struktur global menggunakan SACS, dan analisis lokal elemen hingga pada geometri aktual rack and pinion menggunakan ANSYS. Variasi kedalaman kaki tercelup yang ditinjau adalah 25%, 50%, 75%, dan 100%.
Hasil analisis menunjukkan respon gerak terbesar terjadi pada kedalaman 25%, dengan nilai Gerak signifikan maksimum 0.1036 m dan Percepatan Heave maksimum 0.043 g, Gerak signifikan maksimum roll 0.128 deg dan percepatan roll maksimum 0.130 deg/s2, Gerak signifikan maksimum pitch 0.222 deg percepatan pitch maksimum 0.230 deg/s2. Pada analisis global SACS, Unity Check (UC) terbesar sebesar 1.74 diperoleh pada kedalaman 100%, melebihi batas izin desain sehingga perlu dilakukan analisis lokal. Hasil analisis lokal ANSYS menunjukkan tegangan Von-Mises sebesar 65.41 MPa yang mana masih di bawah yield strength material sebesar 248 MPa. Perbedaan tersebut disebabkan oleh simplifikasi pemodelan pada analisis global yang hanya berupa 1 gigi penahan. Sedangkan pada analisis lokal pemodelan dapat dilakukan dengan geometri aktual berupa 2 gigi penahan sehingga distribusi beban tidak hanya pada 1 gigi sehingga tegangan yang terjadi menjadi lebih kecil.
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The leg lowering phase of a jack-up platform is a critical operational condition in which the structure is highly susceptible to environmental loads, including wind, waves, and currents. This study aims to evaluate the hull motion response and the stress distribution in the rack and pinion system during this phase under the environmental conditions of the Madura Strait. The methodology integrates three stages of analysis: motion response analysis using MOSES, global structural analysis using SACS, and local finite element analysis of the actual rack and pinion geometry using ANSYS. The investigated leg penetration depths were 25%, 50%, 75%, and 100%. The results indicate that the largest motion response occurred at a 25% leg penetration depth, with a maximum significant heave motion of 0.1036 m and a maximum heave acceleration of 0.043 g, a maximum significant roll motion of 0.128° and a maximum roll acceleration of 0.130°/s², and a maximum significant pitch motion of 0.222° with a maximum pitch acceleration of 0.230°/s². The global structural analysis performed in SACS yielded the highest Unity Check (UC) value of 1.74 at the 100% leg penetration depth, exceeding the allowable design limit and therefore requiring a detailed local analysis. The local finite element analysis conducted in ANSYS showed a maximum von Mises stress of 65.41 MPa, which remains well below the material yield strength of 248 MPa. This discrepancy is attributed to the modeling simplifications adopted in the global analysis, where the rack and pinion system was represented by only a single load-bearing tooth. In contrast, the local analysis employed the actual geometry consisting of two load-bearing teeth, allowing the applied load to be distributed between both teeth and consequently resulting in lower stress concentrations.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Jack-Up Platform, Rack and Pinion System, Penurunan Kaki, Von-Mises, Respon Gerak, SACS, ANSYS Jack-Up Platform, Rack and Pinion System, Leg Lowering, Von-Mises Stress, Motion Response, SACS, ANSYS
Subjects:	T Technology > TC Hydraulic engineering. Ocean engineering T Technology > TC Hydraulic engineering. Ocean engineering > TC1680 Offshore structures
Divisions:	Faculty of Marine Technology (MARTECH) > Ocean Engineering > 38201-(S1) Undergraduate Thesis
Depositing User:	Iman Sinergi Ramadhan
Date Deposited:	27 Jul 2026 03:12
Last Modified:	27 Jul 2026 03:12
URI:	http://repository.its.ac.id/id/eprint/137710

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