The Methodology of Fatigue Reliability Assessment for Marine Structures and a Case Study

In order to traditionally investigate the strength of marine structures, the structure is subjected to a maximum static load. However, the marine structures are usually suffering environmental forces varying with time. Wave forces are the most important time dependent loading that causes fatigue in structural elements and joints. In this paper different methods base on S-N curve and linear elastic failure mechanics are presented. The governing equations and theories that are used in each method are expressed and the application of each method will be discussed.The two main methods of deterministic analyses are: stress-based approach (S-N curve approach) and linear elasticfracture mechanics (LEFM) approaches. These approaches are applicable to different analyzing strategies, ie the firstapproach is used for cases in which general form of fatigue is dominant, but the latter involves the calculations ofreliability as functions of crack geometry and its boundary conditions. The SPD12C jacket platform is also modeled as a case study and the results of fatigue reliability analysis are presented

Keywords:

fatigue , reliability , marine structure , S-N curve , LEFM