A practical method for combination of fatigue damage subjected to low-frequency and high-frequency Gaussian random processes

This paper addresses the combination of fatigue damage for offshore steel structures subjected to low-frequency and high-frequency Gaussian components. Two new formulae (Eq. (25) and Eq. (38)) are developed. To verify the accuracy of the two formulae, extensive numerical simulations on bimodal spectra are carried out, and the results calculated by the two new formulae are satisfactory. In particular, compared with other methods (DNV methods, Huang-Moan method, Temple method, Combined spectrum approach, Jiao-Moan method, Low's bimodal method and Low-2014 method), one of two formulae (Eq. (38) in this paper) is accurate and simple enough and valid for a wide range, which shows a strong attraction for application in engineering design.