RAMSSHEEP analysis: A tool for risk-driven maintenance. Applied for primary flood defence systems in the Netherlands

Introduction Floods are a threat to millions of people who live in lowlands like the Netherlands. Therefore the Dutch government has been given re-quirements for primary flood defence systems like dikes. The current condition of most of these dikes does not fulfill to these requirements based on flood risk analyses of RWS. The most logical step is to take measures by constructing new structures or planning regular maintenance activities over time. It is most commonly used to focus on economical most beneficial measures and maintenance intervals for a primary flood defence system like the Afsluitdijk. Research goal RWS aims to launch a certain risk-driven maintenance concept named RAMSSHEEP which should be developed by the current market. The objective is to assess whether or not RAMSSHEEP can be applied as a risk-driven maintenance tool for primary flood defence systems based on the results of the existing method of Probabilistic Approach. By describing the two approaches of a flooding problem more insight will be gained in the advantages and disadvantages of RAMSSHEEP. Methodology and approach A general flooding problem has been ap-proached by analyzing the system on its main functions. Subsequently, a probabilistic analysis has been made by estimating the possible damage and its annual probability of occurrence which together lead to the monetary risk. To decrease this probability of occurrence some measures can be taken which will cost a certain amount of money. Eventually these investments will be analyzed whether or not this amount is lower than the expected level of damage in the old situation, so is the criterion of gaining safety larger than the improvement costs met? Moreover, it is not always profitable to take such investments in an existing system. There-fore maintenance can be applied to decrease the probability of occurrence temporarily. Dominant failure events have been approached by describing scientific deterioration models which illustrates decrease of strength over time. A maintenance optimization describes the most economical beneficial time intervals in which maintenance should be applied based on the deterioration model. Eventually these results form the basis for the translation to RAMSSHEEP requirements. This result illustrates which requirements have been used and which not. This comparison (Proba-bilistic Approach vs. RAMSSHEEP) gives more grip on the assessment of the correctness of RAMSSHEEP as a risk-driven maintenance tool in the hydraulic engineering. Conclusion and recommendation The probabilistic analysis always gives the most economical beneficial solution which forms the main driver of all the problems in society. RAMSSHEEP has proven not to be able to use as a risk-driven maintenance tool with economics as the main driver. By combining the probabilistic analysis and maintenance optimization, it is recommended to apply a new given model named EMAR.

Subject

probabilistic approach
RAMSSHEEP
economical optimization
maintenance strategies
reliability
availability
afsluitdijk
primary flood defence system

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2012-10-05

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master thesis

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