Fatigue analysis of ship deck structure accounting for imperfections

This paper analyses the stress concentration factors of a deck structure, accounting for several structural imperfections. The studied imperfections are generally present in the stress response characteristics and fatigue damage model applied. Besides commonly present uncertainties in fatigue ship structural analysis associated with structural modelling and the random wave induced loading there are also uncertainties arising from imperfection of structural joint that may occur during manufacturing and the interaction between wave induced load and structure. This work analyses longitudinally stiffened welded decks of a containership based on finite element method and evaluates the hot spot stress distributions and stress concentration factors that result from different types of imperfections. The hot spot stresses and the stress concentration factors are defined at the places alongside to the transverse weld accounting for different imperfections. The paper deals with the influence of the imperfections over the hot spot stress distribution and not with the reasons for their appearance.