FAST FATIGUE ASSESSMENT PROCEDURE FOR OFFSHORE STRUCTURES UNDER RANDOM STRESS HISTORY.

In many areas of engineering, such as the offshore industry, design and feasibility studies involve estimating the fatigue life of structural components under long and complex random loading. Usually, power spectra representing different states of load history are obtained from dynamic stress analyses, and these spectra will be used to estimate the fatigue damage. In the offshore industry there are often several design options to be assessed. Coupled with the many sea states involved in a fatigue load history analysis, the calculations can become very costly and time-consuming if the stress power spectra have to be realised in the time domain and then counted cycle by cycle. This paper briefly reviews the state of the art of the prediction models available to bypass the expensive procedure just described. This paper will also report a new and fast prediction procedure for assessing the random stress history for fatigue analyses applicable to offshore structural applications.