TB/T 1878-2002 English PDF (TBT1878-2002)

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TB/T 1878-2002: Prestressed concrete sleeper fatigue test methods
TB/T 1878-2002
TB
RAILWAY INDUSTRY STANDARD OF
THE PEOPLE’S REPUBLIC OF CHINA
Replacing TB/T 1878-1987
Fatigue test method for prestressed concrete sleepers
ISSUED ON: MAY 17, 2002
IMPLEMENTED ON: DECEMBER 01, 2002
Issued by: Ministry of Railway of PRC
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Test equipment and measuring tools ... 4
3 Test pattern ... 4
4 Test steps and methods ... 6
5 Test report form ... 7
Appendix A (Informative) Fatigue strength inspection record of prestressed concrete
sleeper ... 8
Fatigue test method for prestressed concrete sleepers
1 Scope
This standard specifies the fatigue test method for standard gauge railway prestressed
concrete sleepers (including switch sleepers, wide sleepers, bridge sleepers).
This standard is applicable to fatigue tests for scientific research, new product
development, product quality inspection of standard gauge railway prestressed concrete
sleepers (including switch sleepers, wide sleepers, bridge sleepers).
2 Test equipment and measuring tools
2.1 The fatigue test of prestressed concrete sleepers (hereinafter referred to as sleepers)
shall use a fatigue testing machine, which has an accuracy level 1 and a loading
vibration frequency between 4 Hz ~ 8 Hz.
2.2 Use a 20X reading magnifying glass, to observe the crack width. The reading
accuracy is 0.01 mm; there is lighting equipment.
3 Test pattern
3.1 The test pattern of the section under the rail is as shown in Figure 1.
4 Test steps and methods
4.1 The sleepers for fatigue test shall be selected from the batches whose static load,
appearance and demolding strength are all qualified in the exit-factory inspection; 6
sleepers shall be selected each time.
4.2 The fatigue test shall be carried out after the age of the sleeper is 28d. The 28d
compressive strength of the concrete in the test batch shall meet the design strength
requirements.
4.3 Fatigue test shall be carried out on 3 under-rail sections and 3 middle sections; only
one section shall be made for each sleeper.
4.4 Characteristic value ρ of fatigue load cycle
4.6 During the fatigue test, attention shall be paid to observe whether the loading meets
the requirements of the test pattern; correct it if necessary.
4.7 The fatigue test shall be carried out continuously. If the test is stopped due to
irresistible factors in the middle, it shall be subject to the 2 million accumulated fatigues;
it shall be indicated in the report.
4.8 Test results
4.8.1 After the sleeper is unloaded after 2 x 106 fatigue cycles, use a scale magnifying
glass, to observe both sides of the test section, within 5 minutes after returning to zero.
The observed position is the position of the outer row of steel wires in the tension area,
where the maximum residual crack width shall not exceed 0.05 mm.
4.8.2 After the sleeper has undergone 2 x 106 fatigue cycles, the failure test shall be
carried out; its failure strength shall not be lower than 80% of the design failure strength;
the design failure strength shall be given by the design drawing. The sign of the failure
state is that the crack width reaches 1.5 mm, OR where there are two or more cracks
AND the maximum crack width reaches 1.0 mm.