SNS COLLEGE OF TECHNOLOGY, COIMBATORE-35 (AN AUTONOMOUS INSTITUTION)

UNIT IV 16CE 401 – DESIGN OF STRUCTURES

PRESENTED BY, O.R.KAVITHA ASSOC PROFESSOR DEPT. OF CIVIL ENGINEERING SNS COLLEGE OF TECHNOLOGY

Dr.Kavitha.O.R. 16CE 401/ DRCS/ 1/34 SNS COLLEGE OF TECHNOLOGY, COIMBATORE-35 (AN AUTONOMOUS INSTITUTION)

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

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Function of A Bridge

A bridge has to carry a service (which may be highway or railway traffic, a footpath, public utilities, etc.) over an obstacle (which may be another road or railway, a river, a valley, etc.) and to transfer the loads from the service to the foundations at ground level.

Dr.Kavitha.O.R. 16CE 401/ DRCS/ Bridge 3/34 SNS COLLEGE OF TECHNOLOGY, COIMBATORE-35 (AN AUTONOMOUS INSTITUTION) Components of bridge • Super structure • Sub structure • Adjoining structure

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Super structure • Beams, Girders • Arch, Cables • Flooring • Bearing • Parapet wall, Hand Rail

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Dr.Kavitha.O.R. 16CE 401/ DRCS/ Bridge 7/34 SNS COLLEGE OF TECHNOLOGY, COIMBATORE-35 (AN AUTONOMOUS INSTITUTION) Sub structure The components of the bridge below the level of bearings is known as Sub Structure. • Abutments • Piers • Wing walls • Foundation for abutments and Piers

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Classification of Bridges

• Based on material • As per alignment • As per location of bridges • Purpose • Acc. To type of super structure • Acc. To HFL • Acc. To type of span • Acc. To span length • Acc. To navigation facilities • Acc. To loading • Acc. Life of bridges •

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Classification of Bridges

3.Rcc Bridge 4. Steel Bridge

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Classification of Bridges

1.: 2. Stone Masonry Bridge

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Classification of Bridges

5.Prestressed concrete bridge 6. Composite Bridge

Dr.Kavitha.O.R. 16CE 401/ DRCS/ Bridge 12/34 SNS COLLEGE OF TECHNOLOGY, COIMBATORE-35 (AN AUTONOMOUS INSTITUTION) Classification of Bridges

1. Straight Alignment: When the alignment of bridge is perpendicular to the centre line of a river, it is called straight bridge.

2. Skew Bridge: When the alignment of a bridge is not perpendicular to the centre line of river, is called Skew Bridge

Dr.Kavitha.O.R. 16CE 401/ DRCS/ Bridge 13/34 SNS COLLEGE OF TECHNOLOGY, COIMBATORE-35 (AN AUTONOMOUS INSTITUTION) Classification of Bridges

Deck Bridge: When the bridge flooring is provided at the top of the super structure, it is called deck bridge

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Classification of Bridges 2. Through Bridge 3.Semi-Through Bridge: When the bridge flooring is provided at the When the flooring is located at bottom of the super structure, it is called some intermediate level in the super Through Bridge structure, it is called Semi-Through Bridge.

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1.Aquaduct: 2. : It is small bridge It is a long continuous structure which constructed over a stream which remains carries a road or railway like bridge over dry for most part of the year is called dry valley composed of a series of spans aquaduct trestle bents instead of solid piers

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3.Grade separator 4. Viaduct: When two roads crosses each other and It is a long continuous structure which there is considerable differences in their carries a road or railway like bridge over formation level, a bridge structure is dry valley composed of a series of spans constructed , which is known as grade trestle bents instead of solid piers separator.

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Classification of Bridges

4. Highway Bridge: It is constructed on a roadway for the movement of vehicles

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Classification of Bridges

5.Railway Bridge It is constructed for the railway. 6.Foot Bridge A foot bridge is a bridge exclusively usedZfor carrying pedestrians, cycles and animals.

7.Pipe Bridge It is used to support pipeline for water, gas, oil, etc.

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Classification of Bridges

Slab Bridge: Girder Bridge: When the span of bridge is 3 to 6m, slab When the span of a bridge is more, flooring is bridge is used, It is also called culvert. supported on RCC or steel girder. Such type of bridge is called girder bridge

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Classification of Bridges 3. When the flooring of a bridge is supported over steel trusses it is called truss bridge. Normally such type of bridges are used for railways

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Classification of Bridges 4. Suspension bridges consists of sets of cables hanging in a curve from which the roadway is supported. A flooring load is transferred suspenders and cables to the piers.

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Classification of Bridges 5. In such type of bridge the weight of flooring is transferred to the piers through the arch. the floor beam is suspended trough hangers from arch.

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1. Submersible bridge or 2. Non-Submersible bridge: causeway: xIn this types of bridge formation level A road causeway is a pucca dip which is kept above the HFL, so that allows floods to pass over it. It may or maximum flood does not affect the may not have openings or vents for traffic on the bridge. low water to flow.

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1..Simply supported Bridge: 2. Continuous Bridge: When the bridge girders are simply When the super structure of a bridge is supported on piers, it is known as continuous over more than two simply supported bridges. supports, it is called continuous bridge.

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3.: 4. Balanced cantilever bridge: A cantilever bridge is formed of A balanced cantilever bridge consists of cantilevers projecting from the spans simply supported over cantilever. supporting piers. The ends of a . cantilever bridges are treated as fixed

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1. Culvert - span up to 8m. 2. Minor bridge – span 8 to 30m. 3. Major bridge – span 30 to 120m. 4. Long span bridge – span above 120m.

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1. : In case of swing bridge a central pier is provided with suitable bearing or rollers. The super structure consists of a pair of steel trusses and it can be rotated in a horizontal plan about vertical axis.

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2. : In case of bascule bridge, the entire structure is rotated in a vertical plane about a horizontal axis.

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3.Traverser bridge: In case of traverser bridge, it is so arranged that the whole bridge can fully or partially be rolled forward or backward across the openings. 4.Lift bridge: In this type of bridge the truss is lifted up. 5.: In case of transporter bridge, a moving cage is suspended from an overhead truss with the help of cable or wire ropes.

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1.Temporary bridge: • - KUMBH MELA • boat bridge : COLKATA-RABINDRANATH SETU • flying bridge- West India Quay

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2. Permanent bridge: RCC bridges masonry bridges -Rajasthan steel bridges : Surat tapti river

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1. Class AA bridge – Narmada cable bridge 2. Class A bridge 3. Class B bridge

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• Minimum reinforcement required For thickness up to 100mm, minimum % of reinforcement should be 0.3% •For thickness from 100mm to 450mm, it may be reduced linearly to 0.2% •i.e. P(min)= 0.3 up to 100mm thick sections •P(min)= 0.3- 0.1*[(t-100)/(450-100)] where ‘t’ lies b/w 100mm to 450mm •Minimum reinforcement should be ensured in both directions. •If thickness of section is more than 225mm, layer of bars are required near both face

Dr.Kavitha.O.R. 16CE 401/ DRCS/ Bridge 34/34 Thank You

Dr.Kavitha.O.R. 16CE 401/ DRCS/ Bridge