FROM MONITORED STRAIN DATA TO FATIGUE TESTING HISTORY - THE FORMULATION OF THE WAVE ACTION STANDARD HISTORY (WASH) FOR OFFSHORE STRUCTURES

In order to correlate design and realistic loading parameters, several large scale offshore load history monitoring projects were completed in the last decade. As a result a large amount of data have been collected. The relevant parts of these data were examined by the International Wave Action Standard History (WASH) committee. The committee has then arrived at a recommendation for some standard load histories to be used for testing components in fixed offshore structures. It is unlikely that the load history experienced by one structure will be repeated on another. Therefore, it is necessary to extract from these lengthy records the common factors relevant to fatigue. At the same time, as many characteristics of the load history as possible should be incorporated in order to avoid omitting any hidden factors related to fatigue, which may not be evident from current knowledge. The paper outlines the long process in formulating WASH, which will be used in several international research programmes for obtaining fatigue stress-life (S/N) and crack growth data under realistic loading. Information on the recommended techniques for generating the multiple state broad band random load histories will also be included.