Inspection and Maintenance of Steel Girders-10

8/12/2019 Inspection and Maintenance of Steel Girders-10

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3.3 SPECIFICATION OF STEEL FOR SLEEPERS

Steel channel sleeper is part of dynamic structure(critical loadings) which support directly rails of track ongirders hence steel is used as follows:

3.3.1 Bridges located where service temperature does not fall

below 0C, steel used shall confirm to IS-2062 grade B

fully killed.

Note: Till such time rolled channel not available of steel

to IS-2062 grade B steel confirming to IS-2062 A fullykilled can be used.

3.3.2 Bridges located in below sub zero temperature areas,steel shall be confirming to IS-2062 grade C fully killed.

Note: Steel used for fabrication should be tested one andmust have mill test certificate clearly indicating thespecification and fully killed. Fabricator should maintain

the record of steel used with cast mark for verification ifrequired at later date.

3.3.3 Rolled section should be within the rolling tolerances andsurface defects prescribed in IS-1852.

3.4 SIZE AND LENGTH OF SLEEPER

There are two type of steel channel sleepers in use -(1) 150 x 230mm size of cross section(2) 175 x 230mm size of cross-section.

3.4.1 Cross section of sleeper will be 150 x 230mm afterfabrication (if rolled channel used is ISMC 150 x 75) asper Drawing No. B-1636/R

2& B-1636/1-R

2) Fig. 3.3.

3.4.2 Cross section of sleeper will be 175 x 230mm after

fabrication (if rolled channel used is ISMC-175 x 75mm)as per Drawing No.B-1636/2.

3.4.3 Length of steel channel sleeper depends on the type ofsteel girder bridges which is as follows:


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230

ELEVATIO

N

CENTERS

OFGIRDER

OVER

ALLLENGTH

OF

SLEEPER

150

ELASTOMERIC

PAD

F

ig.3.3STEELCHANNELSLEEPERB.G.

PLAN

ELEVATION


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A

B

A

Fig.3.4

TOPFLAN

GEOFSTANDARDPLAT

EGIRDER(WELDEDTYP

E)B.G.

End

portion

Centralp

ortion

End

portion


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3.4.3.1 Standard plate girder rivetted type (B.G.)

Span 24.4m 18.3m 12.2m

Sleeper Length 2550mm 2440mm 2440mm

3.4.3.2 Standard plate girder welded type (B.G.)

The top flange plate of welded girder has different widthat either end and middle portion of girder as shown in

Fig. 3.4. Therefore, length of sleepers on A and Blocation are of different length:

Span 24.4m 18.3m 12.2m

Sleeper length A 2565mm 2440mm 2440mm

B 2725mm 2535mm 2475mm

3.4.3.3 Standard Open Web Steel Girder through Spaneither rivetted type or welded type (B.G.)

Steel channel sleeper rest on floor system i.e. railbearer/stinger, the length of sleeper is same for allspans.

Span 30.5m 45.7m 61.0m 76.2m

Sleeper Length 2440mm 2440mm 2440mm 2440mm

3.4.3.4 Standard Open web (under slung) deck type 30.5mspan

RDSO, Lucknow has not issued any drawing for steelchannel sleeper for B.G. Presently Zonal Railways usesthe wooden sleeper or the steel channel sleeper as perChief Bridge Engineers drawing of their zonal Railways.


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230

150

80

STIFF. PLATE 65x10

TOP PLATE 80x12x250ISMC 150x75 @ 16.4kg/m

7575PLATE 80x10x120

TIGHT FIT

75

230

175

ISMC 175x75 @ 19.1kg/m

TIGHT FIT

7580DIAPH. 80x10x120

STIFF. PLATE 65x10

TOP PLATE 80x12x250

3.4.5.3 Hook Bolts

Hook bolts are of two types.(1) Straight lip(2) Tapered lip

Fig. 3.5 (a) SECTION OF CHANNEL SLEEPER (150 X 230 mm)

Fig. 3.5 (B) SECTION OF CHANNEL SLEEPER (175 X 230 mm)


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Hook bolts are provided to outer edge of top flange plateon either side of girder to anchor the sleeper with the

girder.

Note: Plate girder whether rivetted or welded typerequires straight lip hook bolts. Stinger/rail bearer ofthrough type open web girder requires taper lip to ensurefull grip to rolled angle. Square cross section ofhook bolt near the head will prevent the turning of hookbolts during service ensuring lip of hook bolt in proper

position.3.4.5.4 Elastomeric Pad

Elastomeric/rubber pad between bottom of steel channelsleeper and flange of girder, is essential to prevent crossbending of flange plate causing initiation of cracks in filletweld or root of rolled angle under load. Sleepers aremade up of steel, which is elastic material and cause

cross bending under each axle passing. Thickness ofelastomeric pad is minimum 12mm or as stipulated indrawing.

3.5 FABRICATION OF CHANNEL SLEEPERS

Fabrication of steel channel sleeper is simple andrequired very simple infrastructure hence it can befabricated in civil engineers workshop of zonal railways orby trade. Guide lines issued by RDSO for fabrication ofsteel channel sleepers vide Report No. 135-45 revised inMay 2004 should be followed strictly for fabrication ofthese sleepers.

Steel channel sleeper is part of dynamic loaded trackbridge and support the rail to transfer the load from railto steel girder hence considering safety aspect,

following precautions shall be taken during fabrication toavoid fatigue failure of weld or cracks in steel of HAZ(heat affected zone).


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3.5.1 Precautions

a) All steel section used in fabrication must have milltest certificate clearly indicating the steelspecification conforming to IS-2062 grade B or Cfully killed.

b) All steel plates and rolled section should be straightand free from twist before cutting for fabrication.

c) Oxy-acetylene gas cutting by mechanically controlledtorch shall be used and cut edges to be ground.Profile of plate stiffener shall match with the profile ofinner web and flange plate of both ISMC for snug fitto avoid cracking of weld or root of ISMC below railseat.

d) Welding position shall be flat position (down hand

welding) either by MMAW or CO2welding process aswell as welding is carried out only by the qualifiedwelders.

e) Electrodes shall confirm to IRS-M-28 of class A-2 orC-1 and wire for C0

2 welding shall confirm to

specification of class-1 of IRS-M-46-2001. PreferablyCO2 welding shall be used for fabrication.

g) Welding procedures requires approval and testing asper Clause-19 of Welded Bridge Code-2001 andrecord of fabrication and test qualification shall bemaintained in proforma as stipulated in appendix-V ofIRS serial B1 2001.

h) Before welding, all mill scale and dust adjoining weldface shall be removed and surface shall be cleaned

and to avoid cracking of weld during service.

i) Bearing plates and supporting rails are connected tosleeper by rivet hence drilling of holes in sleeper after


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manufacture and in bearing plate shall be by drillingjig to ensure accuracy in rail gauge and alignment of

rails on bridge. Rivets shall be driven with properheating for the full length of shank to minimizeloosening of rivets during service and reducemaintenance cost.

j) Entire surface of sleeper shall be grit blast cleanedbefore hot dip galvanizing as per IS-2629.

k) Zinc coating weight / thickness is most important

factor from corrosion prevention point of view sincesleeper is in vulnerable location and affected bydisposal of passenger carriage and droppingchemicals and salts from goods wagon. Hencenominal coating weight 610grams/m2 (85-86 micronsthickness) for long life of 15 to 20 years and 750grams / m2 (105 micron) for severe corrosion locationof bridge has to be ensured.

3.6 INSPECTION

To ensure minimum maintenance and safety of public,fabrication shall be in Civil Engineering Workshop ofZonal Railways or from trades who produce satisfactoryevidence of his ability as stipulated in Clause-21 ofWelded Bridge Code 2001.

3.6.1 Inspection shall be in accordance with Clause No.28, 29,

30, 31, 32 and 33 of Welded Bridge Code of 2001 sothat cost of maintenance and repairs will be minimized.

3.7 FIXING OF STEEL CHANNEL SLEEPER ON STEELGIRDERS

Arrangement of fixing of steel channel sleeper, dependson type of steel girder, is as follows:

1) Plate Girder (a) Rivetted type

(b) Welded Type


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2) Open Web through Steel Girder

Steel plate girders of span 12.2m, 18.3m & 24.4m span(either welded construction or rivetted construction) arenot provided with camber as stipulated in steel bridgecode. Therefore rail levels on plate girder as well as onentire bridge has to be in one level.

In welded plate girder same thickness of top flange plateis provided through out the length of girder in different

width as stipulated in para 3.4.3.2 Where as on rivetedplate girder 1stflange plate is provided on entire length ofgirder. 2nd and 3rd flange plate is provided to requiredlength depending upon the cross section required fordifferent length of span. Therefore, top flange plate ofriveted girder is not in one level through out the girder asshown in Fig. 3.6.

To keep rail in one level different thickness of steelpacking plates are required on splice plate, on 1stflangeplate, 2ndand 3rdflange plates.

SE/JE Bridge has to work out the thickness of steelpacking plate by drawing full scale top flange plate ontemplate floor of workshop and mark the sleeper positionto ascertain different thickness of packing platesrequired. To minimize the thickness of packing plate,provide 150x230mm size sleeper with 16mm steelpacking to accommodate the rivet heads on splice plate,so that steel sleeper rest on packing plate instead of onrivet head to avoid rocking of sleeper under running oftrains.

Height of rivet head is 14 or 15mm i.e. 0.7 x d where dis diameter of rivet.

On 3rdflange plate provide 150x230mm size sleeper withincreased thickness of steel packing plate to ensure thetop of the all sleepers are in one level. On 2nd and 1st

Inspection and Maintenance of Steel Girders-10

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