In this slide we talked about various classification of bridges

1. Railway Bridge & Tunnels
Classification of Bridges
5th Semester Dilpoma (Civil)
Lecture – 18,19
15th October 2020 (10 :30AM – 12:30PM)
By
Er. Shubham Gautam
M.E. (CTM), B.Tech (Civil)

2. ARCH
BEAM TRUSS
CANTILEVER SUSPENSION
BRIDGE
ROVING
BRIDGE
Classification of bridges based on structures:
Bridges may be classified by how the forces of tension,
compression, bending, torsion and shear are distributed
through their structure.

3. CLASSIFICATION OF BRIDGES (BEAM
BRIDGES)
Beam Bridges
 Beams are made of different materials of which
the most common are concrete, steel, timber or
aluminum.
 Beams may be used in different parts of a
structure, but in this context, as main carrying
elements, they normally support the bridge deck.
 They are the oldest and simplest bridge design
consisting of vertical piers and horizontal beams -
e.g. just a simple plank or stone slab.

4. Beam Bridges
They are suitable only for short spans but can used for larger
crossings by adding additional piers.
• Forces: As the bridge is loaded, by traffic for example, the
beam bends which causes the top surface to be compressed
and the bottom surface to be stretched or put in tension.
• Advantages: they are easy to build and inexpensive
relative to other bridge types so are very common.
• Disadvantages: they have a limited span and do not
allow large boats or vehicles to pass underneath.

5. Bridges with T - Beams
• For T-Beams, the beams and the deck are rigidly
connected to each other in one type, while in
others, the beam itself is shaped like a T.

6. CLASSIFICATION OF BRIDGES (ARCH
BRIDGE)
ARCH BRIDGES
 These bridges uses arch as a main structural component (arch
is always located below the bridge, never above it).
 They are made with one or more hinges, depending of what
kind of load and stress forces they must endure.
 The arch bridge has great natural strength. Thousands of years
ago, Romans built arches out of stone.
 Arch bridges take normally longer span lengths than vault
bridges because the ribs are designed to resist a load
combination of axial compression and bending moment.

7. CLASSIFICATION OF BRIDGES (ARCH
BRIDGE)
• Today, most arch bridges are made of steel or concrete and
they can span up to 800 feet. They are often chosen for their
strength and appearance.
• The type of structure termed arch includes open and closed
spandrel arch bridges as well as earth filled arch bridges.
• The bridge deck can be either above, between or underneath
the arches. So far as new arch bridges are concerned, the
arch ribs are usually made of concrete or steel.
Forces: the compressive forces created by the load are
transferred down through the arch and
resisted by the supports, or abutments, at its base.
Abutment support prevents the arch spreading under load.

8. Arch Bridges
• Advantages: they are very strong and can
be built from a wide range of materials.
• Disadvantages: limited spans unless multiple
arches (or viaducts) are used and uneconomical
use of materials.

9. CLASSIFICATION OF BRIDGES (ARCH
BRIDGE)
• A closed spandrel arch rib bridge has its side
walls connected to the arch ribs where the
walls are usually made of reinforced concrete.

10. CLASSIFICATION OF BRIDGES (ARCH
BRIDGE)
• An open spandrel arch bridge is usually
constructed of reinforced concrete or in
combination with steel.

11. CLASSIFICATION OF BRIDGES
(TRUSS BRIDGE)
• For this type of bridge the main load carrying element
is the truss, and it is the truss that transfer the loads to
the substructure.
• The bridge deck may be above, between or underneath
the trusses. If the deck is above the trusses, it means
that the deck is above the top chord of the trusses. If
the deck is underneath the trusses, it means that the
deck is situated at the same level as the bottom chord
of the trusses. If the deck is between the trusses, this
means that the deck is situated somewhere between
the bottom and top chord of the trusses.

12. CLASSIFICATION OF BRIDGES
(TRUSS BRIDGE)

13. CLASSIFICATION OF BRIDGES
(CABLE SUPPORTED BRIDGES)
• A Cable Bridge is a bridge in which the
superstructure is directly or indirectly
supported by cables, and where the cables
pass over or are attached to the towers.
• The Static System of a Cable Supported Bridge
is dependent on how the Stiffening Structure
is supported on the towers. It can be either
simply supported or continuously.

14. CLASSIFICATION OF BRIDGES
(CABLE SUPPORTED BRIDGES)
Suspension Bridges
• Suspension Bridges have normally two towers on
which the cables rest, and the tensile forces of
the cables are transmitted to the anchoring at the
extreme ends of the cables.. If there is more than
one main span, a suspension bridge might have
more than two towers.
• The hangers are connected to the cables at one
end and to the cross beams or the stiffening
structure at the other.

15. CLASSIFICATION OF BRIDGES
(CABLE SUPPORTED BRIDGES)
VIADUCT: SEPERATELY SUPPORTED SPANS

16. CLASSIFICATION OF BRIDGES
(CABLE SUPPORTED BRIDGES)
Cable Stayed Bridges
• Cable Stayed Bridges must have at least one tower, but if
there are more than two main spans, two or more towers
have to be provided.
• In the case of Cable Stayed Bridges, the bridge deck is
carried by cables anchored to the upper part of the
tower(s) at one end and to the bridge deck at the other.
Normally the tensile forces of the cables are transmitted to
the tower(s) with anchoring only in the bridge deck at each
side of the tower. Sometimes, however, the cables can be
anchored to the deck at one side of the tower and in the
ground or rock at the other side.

17. CLASSIFICATION OF BRIDGES
(CABLE SUPPORTED BRIDGES)

18. 18
Types of Bridges by use :
 Car Traffic bridge– The most common
type of bridge, with two or more lanes
designed to carry car and truck traffic of
various intensities.
 Pedestrian bridge – Usually made in
urban environments, or in terrain where
car transport is inaccessible (rough
mountainous terrain, forests, etc.).

19. 19
 Double-decked bridge– Built to provide
best possible flow of traffic across bodies
of water or rough terrain. Most offen they
have large amount of car lanes, and
sometimes have dedicated area for train
tracks.
 Train bridges – Bridges made specifically
to carry one or multiple lane of train
tracks.
 Pipelines – Bridges made to carry
pipelines across water or inaccessible
terrains.

20. 20
Pipelines can carry water, air, gas
and communication cables.
 Viaducts – A viaduct is made up of
multiple bridges connected into one
longer
structure. Ancient structures created to
carry water from water rich areas to dry
cities.
 Commercial bridges – Modern bridges
that host commercial buildings such as
restaurants and shops.