Fatigue Behaviour of Offshore Structures

1 Introduction and Literature Review.- 1.1 Mechanics of Fatigue.- 1.2 Fatigue in Offshore Structures.- 1.3 Sea Environmental Loading.- 1.4 Local Stress History at Joints.- 1.5 Fatigue Life Estimation.- 1.6 Significance and Outline of Present Investigation.- 2 Hydrodynamic Loading.- 2.1 Sea Description.- 2.2 Load Description.- 3 Structural Modelling.- 3.1 Idealization of the Jacket Platform.- 3.2 Equations of Motion.- 3.3 Computation of Natural Frequencies and Mode Shapes.- 3.4 Reduced Equations of Motion in Time Domain.- 4 Foundation Impedances.- 4.1 Dynamic Soil Reactions.- 4.2 Soil-Pile Model.- 4.3 Pile-Head Impedances.- 4.4 Pile-Head Dynamic Stiffness Matrix.- 5 Fatigue Damage Evaluation.- 5.1 Evaluation of Structural Response.- 5.2 Local Stresses at the Joints.- 5.3 Fatigue Damage.- 6 Results and Discussions.- 6.1 Pile-Head Impedance Functions.- 6.2 Example Problem.- 6.3 Fatigue Damage Characteristics of a Steel Jacket Structure.- 6.4 Sensitivity Study of Fatigue Damage.- 6.5 S-N Curve Versus Fracture Mechanics Approach to Fatigue Damage Analysis.- 7 Conclusions and Recommendations for Future Work.- 7.1 Conclusions.- 7.2 Recommendations for Future Work.- References.