Approaches for fatigue design of tubular structures

This paper summarizes the methods that are currently most used for the design of tubular structures subjected to fatigue loading. The methods that are mostly used for the fatigue design of tubular structures are the classification method, the hot spot stress method and the mesh-insensitive structural stress method. The classification method is considered to be the traditional method for evaluating the fatigue strength of structural details including nodal tubular connections. In the classification method, nominal stresses are used in the design. The hot spot stress method, on the other hand, uses the so called "hot spot stress". Both the hot spot stress method and the classification method have been incorporated into design standards for many years. The mesh-insensitive structural stress method on the other hand is relatively new and has been recently adopted by the 2007 ASME Div 2 and 2007 API 579/ASME FFS-I Codes and Standards.