Time-variant Ultimate Strength Reliability Assessment of Ship Hulls: Basics, Models, Methods

Ship structures suffer various types of damage while in service. Age-related structural degradations, such as corrosion and fatigue cracks, are considered major types of damage. The purpose of this work is to propose a methodology to assess the time-variant ultimate strength of ship hull girder under the degradation of these damages, to provide a procedure to quickly perform reliability analysis of aging ship hulls, and to develop a more rational renewal and repair schemes that not only consider the maximum allowable corrosion wastage and critical crack size criteria, but also take into account the hull ultimate strength. Time-dependent reliability procedure of a double hull tanker is presented as an example with consideration given to the effects of corrosion and fatigue crack damage on ultimate strength and reliability. It is expected that the methodologies and procedures developed in the present study will provide a useful tool for assessing time-variant ultimate strength and reliability of aging ship hulls.