Structural Modelling and Response Analysis in the New ISO Standard for the Site Specific Assessment of Mobile Jack-Up Units

摘要

There are two ISO documents addressing the site-specific assessment of mobile offshore jack-up units, ISO 19905-1 and ISO 19905-2 [ref. 1 and 2]. 19905-1 is the main ISO standard while 19905-2 is a Technical Report addressing additional information relevant to the assessment of jack-ups, but not critical to the analysis (collectively referred to as 19905 in this paper). Both of these documents have been developed from the SNAME T&R Bulletin 5-5A [ref. 3] (herein referred to as 5-5A). During the development of 19905 from 5-5A there was major restructuring of certain sections, particularly in the area of response assessment. In addition, there were changes in both required and acceptable methods of assessment. This paper explains the most significant of the changes that come under the mandate of ISO TC67/SC7/WG7 Panel 3, which developed the Clauses in 19905 on Structural Modelling and Response Analysis, and provides an indication of their impact on site assessment. Other companion papers in this OTC session on Site-Specific Assessment of Mobile Jack-Up Units address how other parts of 19905 differ from 5-5A.rnThe approach chosen for the ISO standard is somewhat different from that in 5-5A, and it (19905) should produce a more complete and consistent assessment of jack-up operability. The jack-up site-assessment ISO standard will be increasingly used throughout the world, and it is vital that users understand how the methodologies originated, and how to interpret the document.