The Influence of Ship Collision Parameters on the Global Nonlinear Dynamic Response of a North Sea Jack Up Platform

Abstract

In the present study, the influence of ship collision parameters related to vessel impact energy and also the impact scenario on the global nonlinear dynamic behavior of a threeleg jackup platform is investigated. A NorthSea threeleg jackup platform is studied as a case which is located in water depth of about 105 m. Nonlinear elastoplastic and hyperelastic type spring models are used for ship bow and broadside impacts. A nonlinear elastoplastic type spudcansoil interaction model is also applied. Loose sand to medium dense sand profile is considered at the seabase. The effects of ship collision parameters such as ship mass and velocity, impact direction, hit point on jackup as well as the spudcansoil interaction are studied. For the first time, the supply vessel impact energy level far beyond 14 MJ as conventionally applied for shipjackup leg collision analysis (i.e., higher energy impact) has been also considered. The findings of this study indicated that the type of bow or broadside impact as well as the spudcansoil interaction may have considerable effects on the nonlinear dynamic behavior of the jackup platform during ship collision. It is also found that ship collision in the direction of incident waves with mass of 5000 tons and impact velocity of 5 m/s displacement may have more profound effect on global dynamic response of the jackup platform near ultimate collapse. It is also found in this research work that dynamic postimpact behavior of the jackup platform may be greatly influenced by the combined action of extreme wave and current.