MARINE COMPONENT FATIGUE RELIABILITY

A method is presented for evaluating the fatigue of offshore structura l steel members based on structural component reliability procedure co upled with spectral analysis methods. The approach is based on formula ting a nonlinear performance function that expresses the cumulative fa tigure damage rule the form of Miner's rule. Uncertainties in the cumu lative fatigue damage rule and stress calculation are handled by the t reatment of the parameters in question as random variables. As a measu re of reliability against fatigue, the Hasofer-Lind reliability index of the performance function is calculated using the first-order margin al distribution method. The approach is invariant, accounts for correl ation among random variables, and permits the ordering of the random v ariables and deterministic parameters to be readily performed. A numer ical application on a simple idealized platform is used to demonstrate the method and study the fatigue reliability sensitivity. Results of the analysis indicate that the reliability is most sensitive to uncert ainty in the stress calculation.