present

RAILWAY, BRIDGE & TUNNEL ENGINEERING

Jensi ChikhaliyaGuided:-

Civil:-6th B

Classification of BridgesTopic:-

MAHAVIRSWAMI COLLAGE OF ENGG. & TECH.

Savani MilanRathod RasheshVegad Kartik

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PARTICIPATED STUDENTS

What is a bridge?

A bridge is a structure that spans a divide such as: A stream/river/ravine/valley Railroad track/roadway/waterway

The traffic that uses a bridge may include:

Pedestrian or cycle traffic Vehicular or rail traffic Water/gas pipes A combination of all the above

Components of bridge

SUPER STRUCTURE SUBSTRUCTUREADJOINING STRUCTURE

The components of the bridge above the bearing is known as Super Structure.

Super Structure

Beams, Girders Arch, Cables Flooring Bearing Parapet wall, Hand Rail

The components of the bridge below the level of bearings is known as Sub Structure.

Sub Structure

Abutments Piers Wing walls Foundation for abutments and

Piers

I. Based on material usedII. Location of bridge floorIII. As per alignmentIV. PurposeV. Type of superstructureVI. According to HFLVII. According to SpansVIII.Span Length

Classification OF Bridges

IX. Navigation FacilityX. Life of BridgeXI. As per loadings

Based on the type of Superstructure, the types of bridges are :

Bridge classification on type of Superstructure

I. Slab bridgesII. Girder bridgesIII. Truss bridgesIV. Suspension bridgesV. Arch bridges

I. Slab Bridges II. Girders Bridges Span of bridges is 3 to 6 m, slab

bridge is used It is also called Culvert. R.C.C. slab is directly supported

over two strong abutments

When the span of bridge is more Flooring is supported on R.C.C or

steel girders.

III. Truss Bridge

When the flooring of a bridge is supported over steel truss Normally, such type of bridge are used for Railways. Typical span lengths are 40m to 500m

Suspension bridges consist of sets of cables hanging in a curve from which the roadway is supported.

IV. Suspension Bridge

A. Simple suspension bridgeB. Suspension bridge with stiffening

trussC. Suspension bridge with braced chain

Three types of suspension bridges which shown below

Suitable for deep valley The construction of piers

in the bed of river is avoided

They are light in weight They are economical

There are very few suppliers of bridge cables and machined sockets

Painting is essential for all steel components at regular intervals

The location of the deck is limited

Advantages Disadvantages

In such type of bridge the weight of flooring is transferred to the piers through Arch.

The floor beam is suspended through hangers from Arch. This type of bridge is used when more headroom is required below

the bridge.

V. Arch Bridge

Hinge-less Arch Two hinged Arch

Distributes (spreads out) compressive forces Diverts weight onto its two abutments Tension forces are virtually negligible. The greater curvature, the greater the effects of

tension on the underside of the bridge.  Modern arches typically span between 200 and 800

feet  The ancient Romans built arch bridges and aqueducts

that are still standing today

Choice of Bridge Superstructure

The nature of stream or river Nature of foundation available The amount and type of traffic Climatic conditions Type of available construction

material Availability of labour Availability of funds Time available for construction

Maintenance provisions Strategic consideration Economic consideration Aesthetic consideration

Importance of Bearings

To absorb movement of girders To allow for angular movement of girders due to deflection under the load To allow for longitudinal expansion or contraction due to changes in

temperature To distribute load on a large area To simplify the procedure in design To keep the compressive stress within limits To allow for vertical movement due to sinking of support To transfer horizontal forces due to braking

Bearings

Steel and iron bridges

Fixed bearings

Shallow plate

Deep base

Steel hinge

rocker

Free bearings

Sliding plate

Rocker type

Roller type

Concrete bridges

for slab bridges

Tar paper

Laminated

copper

For girder bridge

LEAD

SLIDE PLATE

WITH

CURVED TOP PLATE

RUBBER

NEOPRENE

Types of Bearings

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