关键词: 4岛式, 半潜船, 结构设计, 中剖面设计, 设计流程, 关键技术, 强度评估

Abstract: The requirements of the loading capacity of semi-submersible vessels are increasing with the diversified and large-scale marine equipment. The 4-island semi-submersible vessel has a fully-integrated main deck that is especially suitable for the transportation of the ultra large vessels and the marine structures. It introduces the structural design and strength evaluation of the conventional 3-island semi-submersible vessels, and discusses the deck load, allowable bending moment shear force and mid-ship section design that affect the cargo capacity of the semi-submersible vessel. These design points of the 3-island semi-submersible vessel are also applicable for the 4-island semi-submersible vessel. Compared to the conventional 3-island semi-submersible vessel, the 4-island semi-submersible vessel has the unique arrangement characteristics of the narrow and long side island that is overhanging the main hull. The structural design should consider comprehensively about the influence of the pipes and equipment for the ventilation and exhaust on the hull structure for the optimization design, and meet the requirement of heavy cargo transportation. It introduces the general idea of the structural evaluation of the 4-island semi-submersible vessel and the analysis of the relevant structural strength and the fatigue of key nodes. The vibration of the overall 4-island semi-submersible vessel and that of its side island are also evaluated to ensure the performance of the ship.

Key words: 4-island, semi-submersible vessel, structural design, mid-ship section design, design procedure, key technology, strength evaluation