2. Bridge is astructure built to span physical obstacles such as
a body of water, valley, or road, for the purpose of
providing passage over the obstacle without closing the
gap below.
Bridge building is not a new science. The sophistication
in bridge building technology has been developing since
the human civilization.
Figure 1:a) Simplest bridge
2
b) The PambanBridge
5. CLASSIFICATION OFBRIDGES
According to the
flexibility of
superstructure
5
According to
the position
of bridge
floor
According to
the inter-
span
relations
According to the
form or type of
superstructure
6. LOADINGONBRIDGES
▪ Dead Load
▪ Live Load
▪ Buoyancy Pressure
▪ Centrifugal force
▪ Earth Pressure
▪ Seismic load
▪ Water pressure
▪ Wind load
▪ Thermal forces
Figure 3: Live
Load
6
9. STEELBRIDGE
• Steel is largely used in construction of bridge for
short as well as long spans.
• Steel has been recognized as economic option for a
range of bridges; for long span bridges, railway
bridges, footbridges, and medium span highway
bridges.
• The world’s first cast iron bridge was built at Telford,
in 1779, by Abraham Darby .
• Steel bridges now have a proven life span extending
to well over 100 years.
9
10. Classification of steel bridges
Steel bridges are classified according to:
the type of traffic carried
the type of main structural system
the position of the carriage way relative to the main
structural system
10
Figure 5: Steel Bridge
11. REINFORCEDCONCRETEBRIDGE
RCC bridges are the earliest form of bridges. They
are easy to construct.
Arches are preferable where Bending moment is
more and they are easy to design.
Site Selection for RCC Bridge
1)Straight reach of the stream
2)Good foundation
3)Well defined firm banks
4)Minimum width of crossing
5)Approaches
1
1
Figure 6: RCCBridge
12. Its not always possible to provide straight deck, when
horizontal curves are to be provided the following design
speed is to be considered:
12
13. SUSPENSION BRIDGE
13
• A suspension bridge is a type of bridge in which the deck
(the load-bearing portion) is hung below suspension
cables on vertical suspenders.
• First Suspension bridge was built in 1433, in eastern
Bhutan by Thangtong Gyalpo.
• Suspension bridge is generally preferred when the span
is more than 200 m for roadway or 300 m for light traffic
like motors.
There are two types of suspension bridge:
Un-stiffened deck type suspension bridge
Stiffing girder type suspension bridge
14. Components of a suspension bridge
14
Figure 7: Components of a suspension Bridge
15. Comparisonof R
C
C
,Steel& Suspensionbridges:
1January 2014 15
Suspension Bridge Steel Bridge RCC Bridge
Steel Cables, concrete or
steel deck used as
construction materials.
Steel frames and concrete
deck.
Reinforced cement
concrete
Better to withstand
earthquake movements
than heavier and more
rigid bridges.
Steel can fully meet the
structural requirement
with even small sections.
Arches are preferred
where more bending
moments occur.
Maintenance cost is high
as the cables needs to be
changed
Maintenance against the
rusting of steel has to be
done regularly which
increases the cost of
maintenance
Their cost of maintenance
is very small.
Installation takes time. Quick Installation. Takes longest time for
installation.
16. BRIDGEFAILURE
16
When a bridge collapses , many lives are put at risk.
Bridge collapse is one of the most dangerous types
of structural failure that can occur.
Causes of Bridge failure
1.Earthquake
2.Fire
3.Boat impact
4.Flood
5.Construction accidents
6.Manufacturing defects
1. Design defects
2. Poor maintenance
Figure 8: BridgeFailure
17. MAINTENANCE OFBRIDGES
17
1. The bearings of girders should be coated with
oil from time to time.
2. The floor system of approaches and bridges
should be properly maintained.
3. The entire drainage system should be
inspected for its proper functioning.
4. The movement of foundations, if any, should
be carefully inspected and all attempts should
be made to stop such further movement.
63. CONCLUSION
63
Bridges connect destinations. Bridges are assets
to mankind and have to last for generations as
the construction of bridge influences the whole
ecosystem and the change is permanent. So
proper planning to adapt the bridge into the
natural ecosystem has to be done. The scope of
Bridge Engineering is ever booming and
technology used in bridge building is also
getting more sophisticated.
