NONLINEAR RE-ASSESSMENT OF JACKET STRUCTURES UNDER EXTREME STORM CYCLIC LOADING: PART 1 - PHILOSOPHY AND ACCEPTANCE CRITERIA

In this series of four papers a procedure for evaluating the ultimate strength of jackets subjected to a rare, extreme storm is presented. The procedure, which is based upon quasi-static cyclic analysis with advanced nonlinear finite element software, verifies that the structure's strength is not unduly degraded when subjected to multiple wave encounters in the extreme storm. On the basis of numerical studies of six North Sea jackets, it is concluded that structures survive the passage of one large rare wave from an extreme storm without failure, are likely to survive the entire storm. Thus, static pushover analysis generally suffices to ensure the structure's integrity. In part I the underlying philosophy of the approach is discussed, acceptance criteria are proposed and the main findings from the other papers are summarized concisely. See also the following three abstracts.