Reliability-based methods in the inspection planning of fixed offshore steel structures

For the continued safe operation of a fixed offshore steel structure, it is necessary for any damage resulting from fatigue, collision or impact to be prevented from leading to either progressive failure or sudden collapse. T he detection of fatigue damage at an early stage in the life of the structu re is, however, difficult and costly, especially sub-sea, but the financial and human consequences of structural failure resulting from inadequate ins pection are likely to be much greater, and need to be prevented. The paper describes research that has been undertaken to enable sub-sea inspection st rategies to be improved. The findings relate the inspection methods used, t he locations inspected and the frequency of inspection to the probability o f local fatigue damage leading to unacceptable structural consequences. Thi s provides a practical way of targeting offshore inspection in order to red uce overall life-cycle costs whilst maintaining adequate levels of system r eliability for the complete structure. (C) 1999 Elsevier Science Ltd. All r ights reserved.