This document discusses the inspection and maintenance of steel bridges. It outlines the various components that should be inspected such as bearings, rivets, camber, and superstructure. Critical locations prone to issues like corrosion, fatigue cracks, and loose rivets are identified. The schedule and process for inspections by different roles is provided. Recommendations for maintenance activities like painting, epoxy coating, and metallizing of steel components are described.

1. REPAIR &
MAINTENANCE OF
STEEL BRIDGES
VINEET GUPTA
SPB-I

2. BRIDGE INSPECTION
 SYSTEMATIC OBSERVATION OF
CONDITION AND BEHAVIOUR OF
VARIOUS COMPONENETS/ PARTS
OF A BRIDGE IS CALLED BRIDGE
INSPECTION

3. AIMS OF BRIDGE
INSPECTION
 To assess structural soundness and
fitness for use
 To identify trouble at the earliest stage
 To keep a systematic record of
condition and behaviour (data bank)
 To plan repair and rehabilitation
strategy and programme

4. SCHEDULE OF INSPECTION
BRIDGE INSPECTOR
 Steel girders including bearings of girders >
12.2m – once in 5 years
 Welded girder – initial inspection after 1 year of
installation, than once in 3 years
 Composite girder – 1 year and subsequently 5
years
 Overstressed girders – at least once in a year
 Early steel girder – Floor System– once in a year
: rest-once in 5 years.
 Steel work, rivet testing, weld test etc.

5. Schedule Of Inspection
AEN/DEN (Bridge)
 Scrutinize – register sent by BRI
 Inspect Bridges referred to him
 Bridges call for inspection
 All overstressed bridges – camber loss
 10% test check of BRIs work
Dy. CE/Bridges
 Scrutinize bridge inspection register
 Inspect Bridges referred to him or call for
inspection

6. BEARINGS
ROLE OF BEARINGS
 Transmission of Forces from
superstructure to substructure
 Vertical
 Horizontal
 To permit movement
 Translation
 Rotation

7. SHIFTING OF ROLLER
BEARING

8. TRANSVINGERSE SHIFT

9. INSPECTION OF BEARINGS
 The longitudinal alignment - straight
and central to base plates.
 The girders - symmetrically placed
 No cavity/ gap between base plate and
bed block
 Bearings are free to move in the
designed manner

10. INSPECTION OF BEARINGS
contd.
 Check the condition of location strip and
guide strip or shearing of rivets
 The anchor bolts - in proper position
and intact. Look for any bend or
shearing of bolt
 Uniform seating of rollers & bearing
strip check with feeler gauge

11. INSPECTION OF BEARINGS
contd.

12. INSPECTION OF BEARINGS
contd.

13. INSPECTION OF BEARINGS
contd.

14. INSPECTION OF BEARINGS
contd.
 All fittings of rocker and roller- Sound
and proper
 Free movement of bearings and
condition of grease
 check both ends of girder are in same
level.

15. CAMBER
 Camber in steel truss girder is provided
upward amount being equal to
deflection of girder under design load
during fabrication and erection so that
girder under full load, truss shall be in
horizontal plane (nominal shape).
 Steel plate girders of span 12.2m,
18.3m & 24.4m span (either welded
construction or rivetted construction)
are not provided with camber

16. PRESTRESSING
 Prestressing of open web steel girder of
track bridge is predeforming of
members during fabrication and
erection of girder to ensure girder
under full design load shall be in
nominal shape to minimise
deformation stresses.

17. MEASURE CAMBER
 During technical inspection, camber is
checked at every panel point of bottom
chords of both truss with the help of dumpy
level or precision level, which will facilitate
the inspection officials to understand the
structural condition.
 As far as possible camber observations are
required to be taken at the ambient
temperature mentioned in the stress sheet.
 Graph in different colour.- Dead Load Camber

18. INSPECTION OF STEEL
SUPERSTRUCTURE
Check the Camber
 Loss of camber/Sagging due to
 Heavy overstressing
 Loss of cross section
 Increased load/fatigue
 Overstressing of joint
 Play between holes and rivets

19. LOSS OF CAMBER
 IF loss of Camber observed –
 Impose SR of 30 KMPH
 Investigate in detail-loose rivets,
corrosion, distortion
 Measure stress in critical members by
Faraday Palmer Stress Recorder or
Strain Gauges
 Check for frozen bearings

20. INSPECTION OF STEEL
SUPERSTRUCTURE contd.
DISTORTION
Plate girder
Top flange- comp member
Web plate near bearings-stress
concentration
Top lateral bracing – excessive
vibration

21. INSPECTION OF STEEL
SUPERSTRUCTURE contd.
DISTORTION
Open web girder
 Top chord – insufficient restraints
 Diagonal web member – made of flat in
mid span
 Bottom chord member – if not braced
properly
 Top lateral/ portal bracing - If not braced
properly
 Frozen bearings

22. DISTORTION -CHECK
 Distortion can be checked visually as
well as by a piano wire stretched
between panel points over the
members
 Sometimes web member i.e. diagonal,
vertical and end rakers in through
girder bridges are hit by moving loads
due to shifting of load in wagons,
particularly ODC. Hence, these
members should be checked at 1.2
meters above rail level for any damage.

23. RIVETS
 3 groups:
 stitch rivets are driven to form a member.
These rivets are driven in workshop and
mostly do not become loose in service life
of girder upto 80 to 100 years
 rivets at joints connecting members. These
rivets transfer the load from member to
joint. Tend to become loose after 40 to 50
years.
 rivets connecting top and bottom lateral
bracings including sway and portal
bracings tend to become loose on account
of vibrations.

24. TESTING FOR LOOSE
RIVETS
 Testing of rivets by rivet hammer chips
off the paint film, making rivet head
steel exposed to environment leading to
corrosion of rivet heads
 During technical inspection rivets should
be tested at the critical locations
 Inspect Rivets for loose rivets
 rivet testing once in 5 years

25. LOOSE RIVET–CRITICAL LOCATION
PLATE/COMPOSITE GIRDER
 Web plate to flange angle at end of
girders
 Bearing stiffener
 Splice rivets of flanges
 Bracing and cross frame connection

26. LOOSE RIVET –CRITICAL LOCATION
OPEN WEB GIRDERS
 Rail bearer – cross girder connections
 Cross girder – panel point gussets
 Panel point main gussets
 Top/bottom lateral bracings

27. CORROSION
Inspect for corrosion/loss of section
Critical locations
 Under wooden sleepers
 Formation of water pocket due to
construction
 Places where dust accumulate
 In vicinity of drainage system
 Area directly affected by diesel loco fumes

28. CORROSION- PAINTING
 The inspecting officials should clearly
indicate the following during inspection:
 i) Major portion of steel work require
only cover coat painting and at some
locations patch painting.
 ii) Steel girder requires complete
painting.
 iii) Only patch painting.
 iv) Paint in good condition, hence no
painting is required.

29. FATIGUE
 Fatigue Cracks
 Fatigue is the tendency of metal to fail
at lower stress level when subjected to
cyclic loading
 Fatigue is becoming important because
of growing volume of traffic at greater
speeds and higher axle loads.

30. LOCATION-FATIGUE CRACK
 Critical locations of cracking;
 i) Ends of diagonal members near middle of
the span due to reversal of stresses.
 ii) Sharp edges at cut notch in stringer
flanges at connections with cross girders.
 iii) Top flange plates or flange angles of plate
girders or rail bearers especially below the
sleepers.

31. LOCATION-FATIGUE CRACK
 iv) Roots of channel and angles on
account of rolling defects.
 v) Corrosion pits at any location in
tension member. Joints where heavy
shear is transmitted.
 To arrest the crack propagation, a hole
should be drilled at the end of the crack
in plate and cover material is provided
with rivets.

32. CANTI LEVER BRACKET CORROSION LOSS

33. TILTED ROCKER BEARING

34. TILTED MULTIPLE ROCKER BEARING

35. GIRDER BOTTOM FLANGE CORROSION LOSS

36. TOP CHORD CORROSION AT JOINT

37. BRACING MEMBER CORROSION LOSS

38. BOTTOM TRUSS CHORD CORROSION

39. BOTTOM CHORD CORROSION AT JOINT

40. CORROSION OF PIN & CRACKING OF HANGER
PLATE

41. GIRDER BOTTOM FLANGE VEHICLE IMPACT
DAMAGE

42. Maintenance of Steel superstructures
 Inspection and recording
 Cleaning and greasing of bearings
 Protective painting system for steel
structures
 Replacement of loose rivets or repair to
weld joint
 Strengthening of steel superstructure
 Replacement of corroded rivets

43. Painting
 Steel girders are prone for corrosion
 Where humidity > 60%
 In coastal areas
 Bridge across creek
 Bridge surrounded by chemical industry.
 Type of traffic
 Public nuisance

44. Painting
Surface preperation
 Use emery paper , wire brush, scrappers
 With power tools
 Blast cleaning – sand or grit
 Flame cleaning – oxy-acetylene flame
(not to be done on plates with
thickness<10mm)
 Luke warm water – 2% detergent

45. Painting
No severe corrosion
 Priming coat
 Heavy coat of ready mixed paint red lead
priming to IS 102 or
 One coat of Zink cromate priming to IS 104
followed by red oxide zink crome priming to IS
2074 or
 Two coat of Zink cromate red oxide primer to
IRS P31
 Finishing coat
 Two cover coats of red oxide paint to IS 123

46. Painting
Severe corrosion
 Priming coat
 Two coats of red lead priming to IS 102
 Finishing
 Two coats of aluminium paint to IS 2339
 Above also recommended for open web girders in
all cases due to better and longer life.
 All floor and top bracing system in electrified
areas with epoxy painting

47. Paint life
 Paint red lead - 4 months
 Paint red oxide – 1 year
 Aluminium
 When paste & oil not mixed – 1 year
 When mixed – 4 months
 Red lead dry paint – No time limit

48. Time lag between paints
 Surface prep and Primer – 24 hours
 Primer coat and first finishing coat – 7
days
 First fininshing coat and 2nd fininshing
coat –7 days

49. Epoxy painting
Should be done for
 Flooring system ( cross girder and rail bearer) in
open web girders
 Top flange plate of plate girder and underslung
girder
 Top bracing system in open web girders in
electrified areas
 Steel girders subjected to salt spray

50. Epoxy painting
 Remove oil/grease using petrolium hydrocarbon
solvent ( IS 1745)
 Prepare the surface by sand blasting
 Primer coat – Epoxy zinc phosphate primer
to 60 micron min. ( RDSO M&C/PCN-102/ 86)
 Intermediate coat – One coat of micaceous iron
oxide to 100 micron . ( RDSO M&C/PCN-103/ 86)
 Finishing coat - two coats of polyurethane
aluminium to 40 micron. ( RDSO M&C/PCN-110/
88)

51. Metallising
Should be done for
 Flooring system ( cross girder and rail bearer) in
open web girders
 Top flange plate of plate girder and underslung
girder
 Top bracing system in open web girders in
electrified areas
 Steel girders subjected to salt spray

52. Metallising
 Zinc chrome primer to IS 104
 Two coat of aluminium paint to IS2339
 Min thickness of metal coating 115 micron
 Surface preparation crucial
 Final cleaning by chilled iron grit G24.
 Final surface roughness as per IS 5909.
 Aluminium to be sprayed as per BS1475

53. Renewal of loose rivets
 Slight slackness does not cause loss of
strength
 Renewal should be done only when in groups
 All hand loose rivets which have lost 50% of
head
 All hammer loose rivets where corrosion has
set in bet head and plate
 In end stiffeners where hammer loose rivets
> 30%

54. Renewal of loose rivets
 Use only pneumatic rivetting
 Not > 10% rivets should be cut at a joint at a
time
 Preferably drill a rivet out than use a rivet
buster
 Rivet to be heated to white hot
 Rivet to be driven and snap removed within
20 sec. After leaving fire
 Length
 Snap head – L= G +1.5 D +1 mm for every 4mm of grip
 Counter sunk – L= G + 0.5 D +1 mm for every 4mm of grip

55. Strengthening

56. CRACKED GIRDER REPAIR

58. Vertical
Member
Diagonal
Member
Flooring
Detail at 'A'
Member broken at node No.1
due to excess corrosion
NEW
GUSSET
PLATE

59. 2 3 4 5 6 7 8
HORIZONTAL LEG OF ANGLE MISSING
DUE TO ACUTE CORROSSION
3' 4' 5' 6' 7'
OHE OHE
VIEW A-A
ADDITIONAL
COVER PLATE

60. CORRODED BOTTOM
FLANGE ANGLE WITH
MISSING LEG BOTTOM SPLICE PLATE
INTACT BOTTOM FLANGE
ANGLE
NEW ANGLES WELDED
TO PROVIDE BOTTOM
FLANGE AREA
CORRODED BOTTOM
FLANGE ANGLE WITH
MISSING LEG BOTTOM SPLICE PLATE
INTACT BOTTOM FLANGE
ANGLE
NEW ANGLES WELDED
TO PROVIDE BOTTOM
FLANGE AREA
CORRODED BOTTOM
FLANGE ANGLE WITH
MISSING LEG BOTTOM SPLICE PLATE
INTACT BOTTOM FLANGE
ANGLE
NEW ANGLES WELDED
TO PROVIDE BOTTOM
FLANGE AREA
BOTTOM SPLICE PLATE
INTACT BOTTOM FLANGE
ANGLE
NEW ANGLES WELDED
TO PROVIDE BOTTOM
FLANGE AREA
INTACT BOTTOM FLANGE
ANGLE
NEW ANGLES WELDED
TO PROVIDE BOTTOM
FLANGE AREA
NEW ANGLES WELDED
TO PROVIDE BOTTOM
FLANGE AREA