A Jack-Up is analyzed at a site with a water depth of 83 musing time domain simulation of irregular seas. The response statistical moments are estimated for a number of case studies, incrementing the basic variables. Based on the statistical information from these analyses a reliability analysis is performed considering the long-term statistics of combined environmental loads. The probability of exceeding levels of the axial force in one leg is studied, Static and dynamic analyses, long term and conditional extreme storm event analyses are performed.
Jack-Up platforms have become a standard tool for operations m shallow water, generally less than 100m. The last years there has been a growing interest to use jack-up platforms to achieve early production Jack-ups are now also applied for all year operations m hostile environments like the North Sea. The horizontal stiffness of a jack-up platform is typically an order of magnitude less than the stiffness of a corresponding jacket structure. Thus the dynamic effects become significant as the fundamental period of a jack-up may typically be m the range 4–8 seconds where also the wave energy is becoming significant. Due to its flexibility a design of a Jack-up IS a great challenge. The larger flexibility of a jack-up implies Other simplified dynamic analysis may be questioned as the knowledge about damping values are difficult to establish due to the items listed above. See also Refs.[1–5). The purpose of this paper has been to establish the reliability of one jack-up structure at a particular site based on a best possible representation of the physical response behaviour by time domain simulation analyses. A reliability analysis is performed by a transformation of the response results. A description of this method is given in the following. For a description of reliability methods m general see [7,8,23)