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STRUCTURAL ASPECTS OF TWIN-BLOCK SLEEPERS
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TYPES OF TWIN-BLOCK CONCRETE SLEEPERS
STEDEF
DESIGNED TO REDUCE VIBRATION
DEFINITION OF SLEEPERS
VDH
DESIGNED TO INCREASE TRACK STABILITY
Any form of support laid transverse to the rail and which is sandwiched by the rail and the ballast
other structural aspects
A twin-block sleeper is used to improve lateral stability by its twin abutments. Corrosion of the steel connecting the blocks has to be prevented to maintain its structural strength.
Vibration is another factor to be catered for by an engineer when designing concrete twin-blocks
WHAT THEY DO
sleepers laid transverse to the rail
as shown here
Transferring vertical, lateral and longitudinal loads from the rail-seat to the ballast, subballst and subgrade layers.
To serve as a means of maintaining track gauge and alignment.
More importantly, the rail fasteners have to be attached to them.
SLEEPERS ARE ONE OUT OF MANY COMPONENTS OF THE RAILWAY
STRUCTURAL ASPECTS OF TWIN-BLOCK SLEEPERS
THE ISSUES
The main structural aspects of sleepers (twin-block included) an engineer aims to satisfy are :
1. Vertical Deflection of Sleepers (twin-block)
2. Bending Stress of Sleepers (twin-block)
3. Sleeper (twin-block) Ballast Contact pressure
Thus; the various factors influencing the design of sleepers are:
1
2
Of particular interest based on the course-work is the twin-block concrete sleeper
The static and dynamic loads imposed on rail seats which dependent on;
• The type of track (straight or curved)
• It’s construction and standard of maintenance
• The axle load and their spacing
• The running characteristics, speed and standard of maintenance of vehicles.
The ballast reaction on the sleeper, which is influenced
by;
• The shape of the sleeper.
• It’s flexibility and spacing.
• The unit weight of the rail.
• The standard on maintenance of the track.
• The characteristics of the ballast.
what are twin-block sleepers?
an assembly of two concrete blocks connected by steel bars.
Design of sleepers regardless of type is always in relation to the track system
In summary, the structural aspects of sleepers (twin-block included) relates to an understanding of its mechanical behaviour under usage in relation to other rail components.
some of these include
1. vertical deflection
2. bending stress
3. sleeper-ballast contact pressure
THANK YOU.
Rheda 2000 B355 W60M DESIGNED DUE TO THE NEED FOR HIGHer SPEED LIMITS