Design of Prestressed Concrete Sleeper Based on Ultimate Limit State Approach

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Date

2017-12

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Publisher

Addis Ababa University

Abstract

Railway prestressed concrete sleepers are amongst the vital components of the rail track superstructure, and play significant role in providing integrity, and safe operation of the tracks. Due to the combined effect of the weight burden from the train, and the dynamic load as a result of the train motion, sleepers are subjected to both static and dynamic loading conditions. To achieve the desired service life of railway system, sleepers can be designed to carry and transfer the wheel loads from the rails to the track foundation. Current design philosophy for prestressed concrete sleeper is based on permissible stress principle taking into account only the static and quasi-static loads, which are unrealistic to the actual dynamic loads on tracks. However, there still shortcomings when viewed from the limit state design perspective. Henceforth, limit state function needs to be included in the current design approach as an improvement. There is a need to improve the current understanding of the design of prestressed concrete sleepers by reliability based design method by formulating limit state function. The limit state function depends on reliability index, and load and resistance factors determined through calibration based on available statistical or scholastic data. This paper, tries to follow the ultimate limit state design approach for axial, flexure, and shear design of sleeper by taking into account the compressive and tensile stresses at both initial and final stages of concrete and prestress wires.

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Keywords

Prestressed concrete sleeper, Ultimate limit state, permissible stress, axle load, dynamic load, axial, shear, flexure

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