Review of the mathematical background to the development of realistic load histories for fatigue testing relevant to tubular structures in the North Sea

Following the discovery of oil and gas, fixed welded tubular steel platforms were first installed in the North Sea in 1966. They are subjected to significant fatigue loads due to wave action. A report on proposed standard load histories was published in 1976. These were based on theoretical calculations. In 1979, increasing interest led to the formation of the Wave Action Standards History (WASH) Working Group. Strain gauge data for platforms in the North Sea were made available to the Working Group so later standard load histories were based on service data rather than theoretical calculations. Mathematical techniques used are reviewed, and some load histories are described as case studies. A framework was developed that could be used to formulate a particular standard load history but left open the option of incorporating alternative features, with relatively little additional work.