Bridges

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BRIDGES

TEAM 6GuiDE: ASST. PROF. PREETI GHOSHDEEWAS KHARKA, 1111064SUBHAM KUMAR RAY, 1111021PENCHEN LEPCHA, 1111072

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INTRODUCTIONBridge is a structure 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 b) The Pamban Bridge

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IMPORTANCE OF BRIDGESConnects Difficult TerrainsEasy Trade and Transportation of GoodsReduces Travelling TimeMilitary usePolitical and Economic importanceLess Emission due to displacement

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COMPONENTS OF A BRIDGE

Figure 2:

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CLASSIFICATION OF BRIDGES

According to the flexibility of superstructure

According to the position of bridge floor

According to the inter-span relations

According to the form or type of superstructure

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LOADING ON BRIDGES Dead LoadLive LoadBuoyancy Pressure Centrifugal forceEarth PressureSeismic loadWater pressure Wind loadThermal forces

Figure 3: Live Load

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AESTHETICS OF BRIDGESExternal appearanceInternal viewSequential View

GUIDELINES:

1)Beauty and Stability2)Bridge and

Environment Integration

3) Material Choice4)Moderate Lightings

Figure 4: Aesthetics of a bridge

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STEEL BRIDGESteel 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.

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Classification of steel bridgesSteel bridges are classified according to:the type of traffic carriedthe type of main structural systemthe position of the carriage way relative to

the main structural system

Figure 5: Steel Bridge

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REINFORCED CONCRETE BRIDGERCC 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 Bridge1) Straight reach of the stream 2) Good foundation3) Well defined firm banks4) Minimum width of crossing5) Approaches

Figure 6: RCC Bridge

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Its not always possible to provide straight deck, when horizontal curves are to be provided the following design speed is to be considered:

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SUSPENSION BRIDGE 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 bridgeStiffing girder type suspension bridge

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Components of a suspension bridge

Figure 7: Components of a suspension Bridge

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Comparison of RCC, Steel & Suspension bridges: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.

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BRIDGE FAILURE 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 failure1. Earthquake2. Fire3. Boat impact 4. Flood5. Construction accidents6. Manufacturing defects7. Design defects8. Poor maintenance

Figure 8: Bridge Failure

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MAINTENANCE OF BRIDGES1. 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.

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LANDMARK BRIDGES OF INDIA1) The Bandra–Worli Sea Link

Official name: Rajiv Gandhi Sea LinkCarries: 8 lanes of trafficDesign: Cable-stayed Length: 5.6 km Width: 40 mOpened: 30 June 2009

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2) The Howrah BridgeOfficial name: Rabindra SetuCarries: 8 lanes of  roadDesign: Cantilever

Length: 705 m Width: 21.6 mOpened: 3 Feb 1943

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3) The Saraighat Bridge

Official Name: Saraighat Carries: Rail cum RoadDesign: TrussMaterial: SteelLength: 1.49 kmWidth: 7.31 mOpened: 7 June 1963

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CONCLUSIONBridges 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 sophisticated.

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BIBLIOGRAPHY S. Ponnuswamy (Guest faculty IIT Madras )., “Bridge Engineering”

Tata McGrwaw-Hill. 2nd Edition, 2008 Prof. S.R Satish Kumar and Prof. A.R Santha Kumar (IIT Madras)., “

Design of steel structure Journal” , 2006. S.C Rangwala and K.S Rangwala., “ Bridge Engineering” Charotar

Publishing House. 14th Edition ,2012. B.L Gupta and Amit Gupta., “Road, Railways, Bridges, Tunnels &

Harbour Dock Engineering” Standard Publishers.7th Edition, 2009. S. Ramamrutham., “Design of RCC Structures”., Dhanpat Rai

Publishing, 14th Edition ,1989-1999 S.S. Bavikatti., “Structure Analysis”., Vikas Publishing House. 14th

Edition, 2011. Madan Mohan Das, Bhargab Mohan Das and Mimi Das Saikia.,

“Structure Analysis”., PHI Publication. 1st Edition, 2011. Internet surfing

www.wikipedia.com www.pbs.org www.design-technology.org www.britannica.com www.steelconstruction.info www.tatasteelconstruction.com

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THANKYOU