Design seastates for extreme response of jack-up structures
- Stanford Univ., CA (United States). Dept. of Civil Engineering
The extreme response of a jackup structure is studied. The authors considers how design seastate histories can be introduced to reduce the cost of time-domain response analysis. The authors first identify critical wave characteristics for extreme response prediction. In quasi-static cases, the maximum wave crest height, {eta}{sub max}, is shown to best explain extreme deck` sway. For more flexible structures they introduce a new wave characteristic, S{sub D}, based on response spectral concepts from earthquake engineering. Finally, they show how accurate response estimates can require fewer time-domain analyses, provided design seastates are pre-selected to ensure that {eta}{sub max} or S{sub D} is near its average value. With respect to standard Monte-Carlo simulation, these design seastates achieve at least a 50% reduction in response variability, and hence at least a four-fold savings in needed simulation cost. These results may lend insight not only into time-domain simulation but also into more fundamental questions of jackup behavior. They also suggest that at least in quasi-static cases, still simpler design wave methods based on {eta}{sub max} may suffice. They illustrate and evaluate some such design wave methods here (e.g., the ``New Wave`` model and others based on Slepian theory).
- OSTI ID:
- 55778
- Report Number(s):
- CONF-940230--; ISBN 0-7918-1265-0
- Country of Publication:
- United States
- Language:
- English
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