Value of information-based risk and fatigue management for offshore structures

ABSTRACT This paper proposes a framework for the planning of the structural integrity and risk management (SIRM) of offshore structures by utilizing the value of information and action (VoIA) analysis. Multiple structural health information sources, i.e. inspections, structural health monitoring (SHM) and damage detection systems (DDS), are modeled in dependency of the information acquirement state. In the probabilistic modeling, it is distinguished whether the information are predicted or already obtained. Two deteriorating structural system modeling approaches are illustrated and the pre-posterior and posterior updating of the structural system performance is formulated. To enhance the efficiency of the analysis of complex structural systems, a response surface method for load modeling is derived and the model uncertainty of the response surface is explicitly modeled. The formulated approaches are applied to a generic structural system and a typical deepwater jacket platform analyzing four SIRM scenarios. The optimal SIRM strategy is identified by maximizing the VoIA. The results show that the implementation of SIRM can reduce the failure risks and the expected total costs over the service life compared to a scenario without SIRM. It is also observed that information from SHM and DDS can reduce future inspection efforts and enhance the value of SIRM.