Probabilistic fatigue strength modelling based on various statistical approaches for a double-side welded connection

Abstract

S355 steel is currently used in the fabrication of most wind turbine monopile support structures and offshore structures. In these types of structures, most fatigue failures occur in the welded connections where cyclic loading is the main responsible for this phenomenon. For the high-cycle fatigue analysis, the stress life method utilizing S-N curves can be used to determine the strength of a welded joint under fatigue loading. In this research, the evaluation of design S-N curves for a double-side welded connection made of S355 steel is proposed. This study concludes with a comparison between the experimental fatigue curves obtained and the design S-N curves at 5% and 2.3% probability of failure proposed in design codes (EN1993-1-9, DNVGL-RP-C203 standards and IIW recommendations) for offshore structures and general steel structures. For the specimens under investigation, the hot-spot and nominal stress approaches are taken into consideration. The characteristic fatigue curves of the double-side welded connection are obtained using statistical analyses based on the ASTM E739, ISO 12107, Bayesian inference, and Weibull distribution. The hot-spot and nominal stress approaches yield very similar S-N results considering the specimens under study.