Bridge Rule

Guidelines Given by RDSO,LUCKNOW
REGARDING BRIDGE DESIGN.

1. BRIDGE RULES
Presented By
Mohammad Furqan
J.E (Bridge),PA
Presented To
Mohammed Faiz
XEN(B & F) MMR
1
GOVERNMENT OF INDIA
MINISTRY OF RAILWAYS
(Railway Board)

2. PURPOSE
•Specifying the rules/loads for
– Design of superstructure & substructure of
Bridges
–Assessing the strength of existing Bridges
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3. SCOPE
•Loads specified shall be used for
–All Railway Bridges
–Turn Table girders
–Foot Bridges but excluding Road Bridges
•Design detailing shall be controlled by
appropriate code of practice
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4. LOADS
•Loads specified in Bridge Rules :
 Dead Loads
 Live Loads
 Dynamic effects
 Forces due to curvature or eccentricity of Track
 Temperature effect
 Friction resistance of expansion bearings
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5. LOADS CONT.
 Longitudinal Forces
 Racking forces
 Forces on parapets
 Wind pressure effects
 Forces & Effects due to earthquake
 Erection forces and effects
 Derailment loads
 PQRS loads
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6. 1. DEAD LOAD
•Weight of structure
•Permanent Load carried on it
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7. 2. LIVE LOAD
•History
•Present Live Loads
–For Railway Bridges / Rail-cum-road Bridge
–For Foot Bridge / Footpath 4.8 KN/m²
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8. BRIDGE LOADING STANDARDS HISTORY
FOR BG (1676 mm)
Loading Loading
Std.Std.
YearYearMax. Axle Load Max. Axle Load
Engine (t)Engine (t)
Trailing Trailing
Load Load
(t/m)(t/m)
Long. Force (t)Long. Force (t)
Tractive Tractive
Effort (t)Effort (t)
Braking ForceBraking Force
Std. BStd. B
19031903 18.018.0 1.20 t/ft1.20 t/ft -- --
BGMLBGML
19261926 22.922.9 7.677.67 47.647.6 10% of T.L.10% of T.L.
RBGRBG
19751975 22.522.5 7.677.67 7575 20% of T.L.20% of T.L.
MBGMBG
19871987 2525 8.258.25 100100 13.4% of T.L. + 25% of 13.4% of T.L. + 25% of
Axle Load.Axle Load.
HMHM
19951995 3030 12.0012.00 135135 -do--do-
25 T 25 T 20082008 2525 9.339.33 126126 -do--do-
DFCDFC
20082008 32.532.5 12.1312.13 126126 -do--do-
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11. 3. DYNAMIC EFFECT
• Augmentation in load due to dynamic effects should be
considered by adding a load Equivalent to a Coefficient
of Dynamic Augment (CDA) multiplied by the live load.
•For Railway Bridges (Steel)
–CDA for BG Single Track
•CDA = 0.15 + 8 / (6+L), Max. Value-1.0
where L is
i) Loaded length giving maximum stress
ii) 1.5* Spacing of cross girder ( For Stringers)
iii) 2.5* Spacing of cross girder (For Cross girder)
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12. 4. FORCES DUE TO CURVATURE OR
ECCENTRICITY OF TRACK
•On ballasted deck, even on straight line
–Designed for 100mm eccentricity
•On a curved Bridge
–Designed for centrifugal action of moving load
taking all tracks occupied
–Horizontal load due to centrifugal force is
C = WV² /12.95R t/m run
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13. 5. TEMPRATURE EFFECT
•Applicable for
–Portion of Bridge not free to expand or contract
–Temperature limits be specified by Engineer.
•Coefficient of expansion
–For steel & RCC -- 11.7x10*-6 per degree C
–For plain concrete-- 10.8x10*-6 per degree C
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14. 6. FRICTIONAL RESTISTANCE OF EXPANSION
BEARING
•Coefficient of frictional resistance of
expansion bearings are
–Roller bearing 0.03
–Sliding bearings of steel on
•Steel on Cast Iron or Steel 0.25
•Steel on Ferro bestos 0.20
•Steel on Hard copper alloy 0.15
–Sliding bearing of PTFE / Elastomeric 0.10
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15. 7. LONGITUDINAL FORCES
•One or more of following reasons
–Tractive Efforts
–Braking Force
–Resistance to movement of bearing
–Due to LWR over bridges.
–should not be more than the limiting resistance
at the bearing.
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16. 8. RACKING FORCES
•Not Accounted for calculating stresses in
main girder
•For design of lateral bracing
•additional lateral force of 5.88 kN/m as moving
load in addition to wind and centrifugal force.
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17. 9. FORCES ON PARAPETS
•Minimum height
–one meter above adjacent roadway/foot way
surface
• Designed for a lateral horizontal and a vertical
force of
–1.47 kN/m applied simultaneous at top of the
railing/parapet
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18. 10. WIND PRESSURE EFFECT
•Basic Wind pressure
–Equivalent static pressure in the wind ward
direction ‘P’.
–Depends on appropriate wind velocity chosen
as per
•local meteorological records & degree of exposure
•Map given in IS 875 Part III, be used in absence of
meteorological records
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19. 11. Wind Pressure Effect Cont.
•Wind Pressure for railway / foot bridges
–Wind pressure specified shall apply to
•all loaded / unloaded bridges provided
•Bridges does not carry live loads when wind
pressure at deck level exceeds 1.47 kN/m² For BG.
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20. 12. Forces and Effect due to
Earthquake
•Seismic Force
–Acts in three mutually perpendicular directions
•Horizontal (Two Directions)
•Vertical
–For determining seismic forces country is
divided in 4 zones
•Basic horizontal Seismic Coefficient defined for
each zones
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22. Seismic Force Cont.
–Slab, box and pipe culvert need not be designed for
seismic forces
–Consideration of Seismic forces for design of bridge in
different zone
Zone II(.02) & III(.04) -for bridges of overall length
>60m or span >15m
Zone IV(.05) &V(.08) -all bridges
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23. 13. ERECTION FORCES AND
EFFECTS
•Erection Forces to be considered
–Weight of all permanent and temporary material
–All other forces and effects which can operate on
any part during erection
•Allowance be made in design for stresses set
up in any member during erection.
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24. 12. DERAIRELMENT LOADS
•Derailment loads for BG for ballasted deck
bridges as per appendix XXV.
•Load specified shall be applied at top of
ballast
•Load assumed to disperse at a slope of half
horizontal to one vertical.
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26. 13. LOAD DUE TO PLASSER’S QUICK
RELAY SYSTEM (PQRS)
•PQRS is a process wherein old rail along
with sleeper removed & replaced by NEW
Rail.
•Load due to working of Plasser’s Quick
Relay System for BG
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27. 14. ASSESSING STRENGTH OF
EXISTING BRIDGES
•As per existing Bridge Rules except
– Modification in CDA
–Modification in Longitudinal Forces
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