3. A bridge is a structure providing
passage over an obstacle without
closing the way beneath.
bridge is a structure for carrying
the road traffic or other moving
loads over a depression or
obstruction such as channel, road
or railway.

5. Function of A Bridge

16. These are provided as extension
of the abutments to retain the
earth of approach bank which
otherwise has a natural angle
of repose.

18. .

19. Materials for Construction

20. Classification of Bridges
 According to functions :
aqueduct, viaduct, highway, pedestrian etc.
 According to materials of construction : reinforced
concrete, prestressed concrete, steel, composite, timber etc.
 According to form of superstructure :
slab, beam, truss, arch, suspension, cable-stayed etc.
 According to interspan relation :
simple, continuous, cantilever.
 According to the position of the bridge floor relative to the
superstructure : deck, through, half-through etc.
 According to method of construction : pin-
connected, riveted, welded etc.

21. Classification of Bridges
 According to road level relative to highest flood
level : high-level, submersible etc.
 According to method of clearance for navigation :
movable-bascule, movable-swing, transporter
 According to span : short, medium, long, right,
skew, curved.
 According to degree of redundancy : determinate,
indeterminate
 According to type of service and duration of use :
permanent, temporary bridge, military

22. According to the flexibility of
superstructure:
 FIXED SPAN BRIDGES .
 MOVABLE SPAN BRIDGES.

29. Basic Types of Bridges
 Girder/Beam Bridge
 Truss Bridge
 Rigid Frame Bridge
 Arch Bridge
 Cable Stayed Bridge
 Suspension Bridge

30. Girder/Beam Bridge
• The most common and basic type
• Typical spans : 10m to 200m

31. Truss Bridge
• Truss is a simple skeletal structure.
• Typical span lengths are 40m to 500m.

32. Forces in a Truss Bridge
In design theory, the individual members of a simple truss are
only subject to tension and compression and not bending
forces. For most part, all the beams in a truss bridge are
straight.

33. Arch Bridges
 Arches used a curved structure
which provides a high resistance
to bending forces.
 Both ends are fixed in the
horizontal direction (no
horizontal movement allowed in
the bearings).
 Arches can only be used where
ground is solid and stable.
 Hingeless arch is very stiff and
suffers less deflection.
 Two-hinged arch uses hinged
bearings which allow rotation
and most commonly used for
steel arches and very economical
design.
Hinge-less Arch
Two hinged Arch

34. Arch Bridges
 The three-hinged arch adds
an additional hinge at the
top and suffers very little
movement in either
foundation, but experiences
more deflection. Rarely
used.
 The tied arch allows
construction even if the
ground is not solid enough
to deal with horizontal
forces.
Three-hinged Arch
Tied Arch

35. Forces in an Arch
 Arches are well suited
to the use of stone
because they are
subject to
compression.
 Many ancient and
well-known examples
of stone arches still
stand to this today.

36. Cable Stayed
 A typical cable-stayed bridge is a continuous deck with
one or more towers erected above piers in the middle of
the span.
 Cables stretch down diagonally from the towers and
support the deck. Typical spans 110m to 480m.

37. Cable Stay Towers
Cable stayed bridges may be classified by the
number of spans, number and type of towers, deck
type, number and arrangement of cables.

38. Cable Stay Arrangements

39. Cable Stayed Bridges

40. Suspension Bridge
 A typical suspension bridge is a continuous deck with one or
more towers erected above piers in the middle of span. The deck
maybe of truss or box girder.
 Cables pass over the saddle which allows free sliding.
 At both ends large anchors are placed to hold the ends of the
cables.

41. Forces in Suspension Bridge

52. ADVANTAGES
Lightweight
DISADANTAGES
Noisy
Unpleasant ride quality
Possible safety issues
Allows debris and salt laden water through
TYPICALLY ONLY USED
FOR
REPLACEMENT IN KIND.

53. Full-depth grid was introduced by engineers in the 1930
s to speed up construction on large bridge projects
Can be precast or cast-in-place for very quick
installation; high performance to cost ratio
 High durability and longevity are demonstrated by the
great service history
FullyFILLED GRID SYSTEMS

54. FULL-DEPTH CONCRETE FILLED GRID

55. Partially filled grid – first used in the 1950 s to further
reduce weight by eliminating concrete in bottom tension
zone
Can be precast or cast-in-place offering rapid
construction; very
good strength to weight ratio
Proven performance, this LW system offers similar span
capabilities to Full-Depth
Half filled grid decks

56. PARTIAL-DEPTH CONCRETE FILLED
GRID

58. EXODERMIC DECK

64. • Cooling and heating of decks causes deck
contraction and expansion, respectively
• When contraction is restrained, cracking can occur
when the tensile stress exceeds the tensile strength
• When expansion is restrained, distortion or crushing
can occur
• Joints are often specified to accommodate deck
movements without compromising the structural
integrity of the bridge

65. • Bridge deck joints should protect the interior edges
of concrete decks from vehicle loads, seal the joint
openings, and accommodate movements resulting
from temperature changes and creep and
shrinkage of concrete
• Joint failure is a internationwide problem in the
• Failure is not necessarily caused by the joint
material itself but also by careless design, improper
installation, and inadequate maintenance

71.  Accommodate less than 1- in. movements or minor
rotations
 Are sometimes installed with armor angles to protect
concrete slabs
 Are effective only under the assumption that the
passage of water and debris through the opening will
not have adverse effects on the supporting
substructures

73. Sliding Plate Joints

75. •

92. •