Risk and reliability, and consequential issues including exposure levels, action probabilities, limit states, and action factors, are integral components of the philosophy for safe and competitive design of offshore structures, as implemented in the ISO 19900-series of International Standards. These standards describe a limit state based design procedure that is intended to result in a structure with an appropriate level of reliability and acceptable performance. Despite recent clarifications to the general design approach, gaps remain in the general standards. This paper discusses the issues as relevant for arctic offshore structures. It identifies gaps that are closed and issues that need to be taken further in the specific standard for arctic offshore structures. These issues include reliability targets, "abnormal"' environmental conditions, "beyond abnormal" conditions, and reserve strength of gravity-based structures. Risk and reliability in design can also depend on operating philosophy and practices (e.g. ice management, disconnection of floating structures) with consequent modification of design action hazard curves.
展开▼
