Risk and reliability assessment of marine operations

Marine structures are widely used in the oil and gas industry, marine transportation and exploration areas and renewable energy applications. Understanding dynamic behaviour of these structures is necessary to allow their evaluation under the effects of environmental loads such as wave, wind and currents. However, the sea environment is very complex, and the response of these structures is affected by considerable uncertainties that should be predicted accurately. Due to the stochastic trend of the sea environment, different types of failure are expected to be observed during the life time of a structure. Consequently, failure of a marine structure may pose various major risks in terms of environmental pollution and loss of assets for companies. Therefore, a great deal of research on the improvement of marine safety is carried out to mitigate the associated risks. It is also necessary to take into account the process of risk escalation in a more realistic way than relying only on either precursor data or expert judgments. This requires a comprehensive approach when it comes to accident modelling and risk analysis of marine structures. This PhD research is focused on developing advanced probabilistic models for representing dynamic risk assessment of marine structures in a harsh environment. The developed frameworks will assist industries to model marine accidents and improve the reliability of marine structures to minimize the risk of failure. The main content of the thesis investigates a developing practical framework for incorporating the reliability of floating offshore structures while considering hydrodynamic performance of the structure as real monitoring data based on modelling the physics of the failure. In order to evaluate response of the marine structure in harsh environment, the storm condition was developed to help researchers to generate necessary data for conducting reliability assessment of the system. The outcome of this achievement led to analysis performance of either the marine structure or the human on board for future risk analysis and decision-making. As a result, the developed methodologies include time-dependent reliability strategies that can model long-term failure scenarios in marine environment which is able to consider marine accident and human failure in respect to the time of operations. Overall, this thesis provides a comprehensive probability model for evaluating the dynamic risk assessment of marine structures under different operational conditions. The outcome of this research will assist industries to improve the reliability of the structures in the design phase or in their operating conditions to mitigate the associated risks to assets, human life and the environment.