Research communities of various engineering and physical science fields have in the last year placed a lot of emphasis on modelling the ways climate change affects different engineering systems and therefore influences the methods by which these systems are designed. With a progressive change of our global climate to warmer and more variable conditions worldwide the effects of extreme weather changes are becoming now, more than ever, evident to our everyday lives and affect our safety. It is this effect of climate change that engineers now face the task of incorporating in their design of engineering systems, especially in the ship and offshore-related fields. In such cases of mathematical modelling and analysis variations of more than one variable that is climate dependent can significantly affect the design. The fact that ship structures do encounter temperature conditions that induce thermal stresses and deformation of practical importance has been recognized for some time. The need to develop efficient techniques of modelling extreme environmental phenomena is hence now more relevant than ever in the history of this type of research. A large amount of research exists in the area of extreme wave phenomena and their effects but in terms of extreme temperature and the effect of diurnal temperature changes research published has been very limited. This paper places emphasis on the modelling of loads for use in reliability analysis. Load combination methodology is used for the combination of wave bending, still water, slamming and thermal loads using various stochastic methods for load combination. A case study of an FPSO/Tanker vessel is analysed and diurnal temperature cycles, on structures already in operation in the North Sea/West of Shetland area, are modelled using these load combination techniques. Load combination factors are then introduced for calculating the total hull girder bending moment. Corrosion effects on the structure are modelled using a simple mathematical model derived from actual vessel measurements, statistical analysis and published research. Reliability analysis using a FORM-SORM component approach provides Partial Safety Factors and probabilities of failure.
A study on reliability analysis for water resources systems.
