Browsing by Author "Mesfin, Kebede"

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    Flexural Performance Evaluation of Different Countries Concrete Sleepers for The Case Of Ethiopian Railway Track Design
    (Addis Ababa University, 2015-07) Mesfin, Kebede; Tatek, Fikadu (PhD); Mequanent, Mulugeta (Mr.)
    Prestressed concrete sleepers are the most widely used sleeper type in various countries for railway track system. This thesis evaluates the flexural performance of Australian German, British and Chinese prestressed concrete sleepers in comparison with the currently used sleeper in Ethiopia. The state of art of literature review has been discussed in order to assess the experiences of these countries in railway prestressed concrete sleeper. Codes of standards for prestressed sleeper recommended different types of concrete sleepers according to track gauge and axle load capacity. Sleepers are subjected to different types of load such as quasistatic, dynamic load and combined quasistatic and dynamic loading. In some codes like British and German accidental, exceptional and services load are included in the design. Finite element (FE) modeling and analysis is performed using FE software packages ANSYS. The design rail seat load is calculated according to the code provisions of respective countries code of standard. For comparison of the results of rail seat and sleepers center positive and negative loadings, AREMA standard is used as a reference. The result obtained from both rail seat positive and negative loads shows a good result which is below AREMA recommendations. For results obtained from sleeper center loading there was a variation of about average of 20%. The second FE analysis has been conducted according to actual ballast pressure distribution under sleepers provided by each country code and Chinese code. From the analysis result it has been observed that, the Australian and German concrete sleeper shows a good response at rail seat and sleeper center respectively. The German concrete sleeper relatively shows a better result when compared to British concrete sleeper under both rail seat and sleeper center. Finally, dynamic analysis has been made to see how these loads affect the flexural performance of concrete sleepers. The result showed that the Australian and china concrete sleepers observed a large amount of deflection when compared to other. In contrast the German concrete sleeper showed a small deflection. Based on the analysis result the German concrete sleeper was selected in terms of its general flexural performance. Lastly, the recommended sleeper cross-section shows a reduced stress when compared with others concrete sleepers.