LAUSR

Offshore cranes are less frequently used than onshore cranes. Because of the reasons, fatigue analysis of offshore crane has often been ignored or performed with a nominal stress approach based on FEM1,001. Recently, ultra-high tensile steel has been used for crane structure and the speed of cargo handling has been increased. Fatigue has become a major design parameter. Recently owners require a detailed fatigue analysis using a proper load spectrum model. Except API-RP, it is almost hard to find regulations that define load spectrum models. The load spectrum model in API-RP is difficult to apply to the modern cranes. In order to solve the problem, a load spectrum model is presented in this study. The load spectrum model is based on the data recorded in three offshore cranes for three years. The data were statistically analyzed, and a proper load spectrum model was derived.