Multiaxial fatigue analysis of the stress joint for a deepwater steel catenary riser

The object of this paper is to present a more accurate and useful method for fatigue analysis and life prediction for a stress joint of a deepwater steel catenary riser. The stress joint was used to connect the riser and platform, and it was subjected to ocean environmental loadings and erosion; thus, the fatigue problem is critical. First, global time domain dynamic analysis of the steel catenary riser was performed, and then local analysis was performed for the stress joint. Finally, the fatigue life of the stress joint was evaluated according to the multiaxial fatigue theory, and a preliminary parametric study was also carried out. Results show that taking stress value of the structure as the only criterion is not enough, and fatigue analysis is necessary when the structure is subjected to an alternating load. Compared with uniaxial analysis, multiaxial fatigue analysis can reflect the damage of the structure more realistically. Especially for deepwater steel catenary risers, multiaxial fatigue problems should be given close attention.