Numerical Study for Topside Effect on Behavior of Deck Transportation Vessel and Seafastening Structure

Abstract

Transportation method of offshore structures is important as offshore ones are larger and installation depths are deeper. Whereas lower supporting structure is possible to be transported by using its buoyancy, topside is transferred by transportation vessel due to equipment unfamiliar with water such as electric systems, chemical process instruments and so on. Transportation vessel moves in sea environment conditions. Vessel is affected by sea environment, and thus motions of vessel as well as environment have influence on topside structure. To prevent a damage of topside by these effects, additional equipment, seafastening structure is installed. Seafastening structure is installed between vessel and topside and has oblique 16 beam structures. Integration analysis of vessel, topside and seafastening structure is realized by Boundary Condition(BC) transfer method and coupled analysis method. The motions of transportation vessel are analyzed and load on the topside and stresses loaded on the seafastening structure are estimated. Results of analyses are compared each other and these results are also done with those of simplified computation.