Integrity Management of Offshore Structures With Emphasis on Design for Structural Damage Tolerance

Abstract

Based on relevant accident experiences with oil and gas platforms, structural integrity management of offshore structures is briefly outlined, including adequate design criteria, fabrication and operational procedures, as well as life cycle quality assurance and control. The focus is on developing an operational design standard for accidental collapse limit states to ensure robustness or damage tolerance. The focus is to ensure an acceptable safety level against progressive failure leading to total loss in view of initial damage caused by accidental actions due to operational errors and abnormal structural damage due to fabrication errors and abnormal deterioration during operation as well as the actions on the damaged structure and inherent uncertainties. Moreover, the damage tolerance required for achieving safety by inspection, monitoring and repair strategies, is briefly addressed. While the basic damage tolerance requirement refers to the survival of the structure in certain damage conditions, wider aspects of robustness in terms of the structure’s sensitivity to the deviation of action effects and resistances from normal conditions are also briefly addressed. In particular, it is suggested to provide robustness in cases where the structural performance is sensitive to uncertain parameters, by choosing conservative values of these parameters.