Design of Prestressed Concrete Sleeper Based on Ultimate Limit State Approach
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Date
2017-12
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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