This study investigates the fracture failure of longitudinal members including cracks. Specifically, this study employs the failure assessment diagram methodology to assess the conditions of failure at the crack tip. Based on various crack configurations, this study establishes the analytical formulations of the crack-tip condition that are validated using finite element analyses. In addition, the material toughness is expressed in terms of crack-tip opening displacement. This study evaluates the failure stress of representative cracked members as a function of the crack length. This enables determining critical crack lengths corresponding to the maximum stresses derived from extreme loads. Finally, this study uses simplified fatigue crack growth analyses to characterize the critical crack length in terms of fatigue life. For members located in the deck and bottom regions, the critical crack lengths correspond to the end of the assessed fatigue life. Therefore, the fracture resistance of the longitudinal members is satisfactory as it will not cause the premature loss of the component. This study also provides analytical formulations for crack-tip conditions that could be employed in a reliability study linking fatigue crack growth and fracture under extreme loads.

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