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There isn’t a measure in use today, capable of communicating the degree to which a ship structure performs its functions; it either does or does not. Decisions are based on design criteria consisting of factors of safety and design margins. The design margins are based on traditional, implied performance needs and cannot be adjusted to account for new structural technologies, changes to performance requirements or an operational need in case of damage. The use of a static design margin does not allow for a true assessment of the performance of the structure, nor does it allow for proper mitigation of structures-related risks. The adoption of an explicit measure of operational performance is warranted. The proposed ship structures, operational performance measures may be summarized as follows. The Operational Durability performance measure is the probability that the platform structure will not require repair over its design life or remaining lifetime. The Operational Dependability of the ship structure is defined as the probability that the ship structure will “be there” for the mission, once the mission begins. The Operational Capability of the ship structure is the ability of the structure to support operational needs aside from those associated with “being there” in the face of seaway loads. The development of these three performance parameters for ship structures is important to support risk and performance-based management. They serve as a starting point for achieving a completely quantitative, performance-based structural management environment based on existing structural analysis and reliability technologies. |
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