This paper presents an overview of developments in fatigue design standards that have been made in Norway the last few years. During the last 20 years a significant international work has been performed in the area. After a review of this we have based our work on recognised design S-N curves by the International Institute of Welding (the same as Eurocode) and the work on classification of joints in the Eurocode standards. However, these standards (Eurocode and IIW) do not give S-N data for fatigue design of offshore structures in seawater with and without cathodic protection. A review of existing design codes and relevant data have hence been performed to provide a harmonised standard that gives design guidance for onshore and offshore structures exposed to various environmental conditions. The basis for this work is presented in the present paper.
This paper presents an overview of developments in fatigue design standards that have been made in Norway the last few years. Internationally, significant work has been performed in the fatigue area since the issue of the fatigue part of the previous Norwegian standard for design of steel structures (NS 3472) in 1984. Therefore, the literature and a number of other design standards that have been developed in this period have been reviewed. The design S-N curves are of particular importance and their background is presented in the paper. The current International Institute of Welding (IIW) design S-N curves for structures in air are also used in ENV 1993–1–1 (EC 3), and are also used in the new NS 3472. Furthermore, the EC 3 classification of joints is also followed in general. However, neither EC 3 nor IIW give recommendations for fatigue design of offshore structures in seawater.
