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Title: Life Time Management of Rails Based on Structural Reliability Approach
???metadata.dc.contributor.*???: Mequanent Mulugeta (Mr.)
Getnet, Mulatu
Keywords: Rail defects;Rail inspection;Rail deterioration;reliability Analysis;fracture Mechanics;reliability index;event tree Analysis;life cycle cost
Issue Date: May-2015
Publisher: AAU
Abstract: Preventing broken-rail caused derailments is a high priority for the rail industry. The current practice is to periodically inspect rails using non-destructive technologies. Determining the effective inspection frequency is a critical decision in railway infrastructure management. This thesis discusses some applications of the modelling work to rail defect management. In particular, main applications are the determination of remedial actions and effective inspection interval on the basis of the quantitative approach as well as the adaptation of rail inspection and maintenance procedure. The frequency of rail inspection tends to vary from one railroad to another, yet it is usually based on either time or traffic tonnage. Railroad companies have evolved their rail inspection schedules empirically based on long field experience. Rail defect management refers to the development and implementation of strategies to control the risk of rail failure. The primary method to control the risk is a rail inspection through nondestructive evaluation and is a replacement of rails based on the remedial action plan. To demonstrate the feasibility of the above applications first, a Linear Elastic Fracture Mechanics (LEFM) analysis which can predict a crack size in a rail head, web and base is performed. Second, First Order Reliability Method (FORM) of analysis evaluates the reliability of a rail, considering some uncertainties of parameters. Third, an Event Tree (ET) analysis represents systematically all possible events and actions regarding rail defect management. Finally, a Life- cycle cost (LCC) estimation formulates the total expected cost during the service life are conducted. Based on the analysis results, the mechanism for remedial action is developed based on critical crack size at rail head, web and base as well as rail reliability value to help infrastructure manager’s decision. Then, effective number of rail inspection frequency is determined as three times a year to prevent the occurrence of rail failure by taking the required action at the right time, and extend the rail life expectancy, reduce the rail maintenance work and its cost. Finally, appropriate rail inspection and maintenance strategy model (flowchart) is adopted for Ethiopian railway industry.
Appears in Collections:Railway Engineering

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