Studi Numerik Analisa Keruntuhan Progresif Girder Lambung Kapal Akibat Pembebanan Lentur Siklik

Bilbilad, Fiarza (2026) Studi Numerik Analisa Keruntuhan Progresif Girder Lambung Kapal Akibat Pembebanan Lentur Siklik. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Girder lambung kapal yang beroperasi menerima beban lentur siklik akibat gerakan gelombang, yang secara bertahap dapat menurunkan kapasitas kekuatan ultimate struktur hingga menyebabkan keruntuhan progresif. Ketidaksempurnaan awal (initial imperfection) akibat proses fabrikasi turut memengaruhi kekuatan ultimate tersebut, namun kajian numerik mengenai pengaruhnya pada girder lambung kapal di bawah beban lentur siklik masih terbatas. Penelitian ini bertujuan membuat pemodelan girder lambung kapal dengan FE package software, mengetahui karakteristik keruntuhan progresif akibat beban lentur siklik, serta mengetahui pengaruh initial imperfection terhadap kekuatan ultimate struktur. Simulasi numerik dilakukan menggunakan software Abaqus pada model midship section half-compartment dengan pendekatan nonlinear finite element method, pada empat variasi model yaitu perfect, slight, average, dan severe initial imperfection, di bawah beban lentur siklik dengan amplitudo rotasi bertahap (0,5θu; 1,0θu; 1,2θu). Hasil simulasi pada model perfect menunjukkan momen ultimate pembebanan monotonic sebesar 4,137×10¹¹ N·mm. Pada pembebanan siklik, terbentuk loop histeresis yang membesar secara nested tanpa menutup kembali ke titik nol, menandakan akumulasi deformasi plastis permanen, dengan buckling yang terjadi secara bergantian pada pelat deck dan bottom akibat pembalikan arah sagging-hogging. Peningkatan level initial imperfection menurunkan momen puncak sagging, dengan reduksi yang meningkat signifikan pada rotasi yang lebih besar, mencapai 5,53% pada level severe di siklus ketiga.
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Ship hull girders in operation are subjected to cyclic bending loads induced by wave motion, which can progressively reduce the structure's ultimate strength capacity and eventually lead to progressive collapse. Initial geometric imperfections arising from the fabrication process further influence this ultimate strength, yet numerical studies addressing their effect on ship hull girders under cyclic bending loads remain limited. This study aims to develop a finite element model of a ship hull girder using an FE package software, to characterize the progressive collapse behaviour under cyclic bending loads, and to determine the effect of initial imperfection on the ultimate strength of the structure. Numerical simulations were carried out using Abaqus on a midship section half-compartment model with a nonlinear finite element method approach, across four model variations perfect, slight, average, and severe initial imperfection subjected to cyclic bending with a stepwise increasing rotation amplitude (0.5θu; 1.0θu; 1.2θu). The simulation results for the perfect model show an ultimate moment of 4.137×10¹¹ N·mm under monotonic loading. Under cyclic loading, a nested and progressively widening hysteresis loop is formed without closing back to the origin, indicating the accumulation of permanent plastic deformation, with buckling occurring alternately on the deck and bottom plating due to the reversal of the sagging-hogging direction. An increase in the initial imperfection level reduces the peak sagging moment, with the reduction becoming markedly more pronounced at larger rotations, reaching 5.53% for the severe level at the third cycle.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	girder lambung kapal, keruntuhan progresif, initial imperfection, beban lentur siklik, kekuatan ultimate, metode elemen hingga nonlinier, ship hull girder, progressive collapse, initial imperfection, cyclic bending load, ultimate strength, nonlinear finite element method
Subjects:	V Naval Science > VM Naval architecture. Shipbuilding. Marine engineering
Divisions:	Faculty of Marine Technology (MARTECH) > Naval Architecture and Shipbuilding Engineering > 36201-(S1) Undergraduate Thesis
Depositing User:	Fiarza Bilbilad
Date Deposited:	04 Aug 2026 07:19
Last Modified:	04 Aug 2026 07:20
URI:	http://repository.its.ac.id/id/eprint/143237

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