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Bridge Definition
Types of Bridges
Bridge Components
Aesthetic in Bridge Design
Selection criterion of a Bridge Type
Quiz
What is a Bridge?
Bridge is a structure which covers a gap
Generally bridges carry a road or railway across a natural orartificial obstacle such as, a river, canal or another railwayor another road
Bridge is a structure corresponding to the heaviestresponsibility in carrying a free flow of transport and is themost significant component of a transportation system incase of communication over gaps for whatever reason suchas aquatic obstacles, valleys and gorges etc.
700 A.D. Asia700 A.D. Asia
1,304 years 1,304 years agoago
100 B.C. Romans100 B.C. Romans2,104 years ago2,104 years ago
Clapper Bridge
Tree trunkStone
Arch design evenly distributesstressesNatural concretemade from mudand straw
Roman Arch Bridge
History of Bridge DevelopmentHistory of Bridge Development
Great Stone Bridge in China
Low bridgeShallow archAllows boatsand water to passthrough
History of Bridge DevelopmentHistory of Bridge Development
Truss BridgesMechanics of DesignWood
Suspension Bridges
Use of steel in suspending cables
1900 1900
1920 1920
Prestressed ConcreteSteel
2121STSTCENTURYCENTURY
Compression Tension
Basic Concepts Basic Concepts
Span - the distance between two bridge supports, whether they are columns, towers or the abutments.
Compression
Tension -
Force -
Concrete has good compressive strength, but extremely weak tensile strength. steel and cables are good in tesion
Basic Concepts Basic Concepts
Beam - a rigid, usually horizontal, structural element
Pier - a vertical supporting structure, such as a pillar
Cantilever - a projecting structure supported only at one end, like a shelf bracket or a diving board
Beam
Pier
Load - weight on a structure
There are six main types of bridges:1. beam bridges2. cantilever bridges 3. arch bridges4. suspension bridges 5. cable-stayed bridges and 6. truss bridges
Types of Bridges
Consists of a horizontal beam supported at each end by piers. The weight of the beam pushes straight down on the piers. The farther apart its piers, the weaker the beam becomes. This is why beam bridges rarely span more than 45m.
beam bridges
ForcesWhen something pushes down on the beam,
the beam bends. Its top edge is pushed together, and its bottom edge is pulled apart.
Beam bridge
A cantilever bridge is a bridge built using cantilevers: structures that project horizontally into space, supported on only one end.
cantilever bridges
The arch has great natural strength. Thousands of years ago, Romans built arches out of stone. Today, most arch bridges are made of steel or concrete, and they can span up to 800 feet.
arch bridges
Forces
The arch is squeezed together, and this squeezing force is carried outward along the curve to the supports at each end. The supports, called abutments, push back on the arch and prevent the ends of the arch from spreading apart.
Types of BridgesTypes of Bridges
Arch BridgesArch Bridges
Suspension BridgesSuspension Bridges
This kind of bridges can span 600m to 2500m -- way fartherthan any other type of bridge! Most suspension bridges have atruss system beneath the roadway to resist bending andtwisting.
Types of BridgesTypes of Bridges
Forces
In all suspension bridges, the roadway hangs from massive steel cables, which are draped over two towers and secured into solid concrete blocks, called anchorages, on both ends of the bridge. The cars push down on the roadway, but because the roadway is suspended, the cables transfer the load into compression in the two towers. The two towers support most of the bridge's weight.
Types of BridgesTypes of Bridges
Suspension BridgesSuspension Bridges
cable-stayed bridges
The cable stayed bridge is newer than the other types of bridge. Large upright steel supports are used to transmit the load into the ground.
Truss Bridge
All beams in a truss bridge are straight. Trusses are comprised of many small beams that together can support a large amount of weight and span great distances.
Pontoon bridges are supported by floating pontoons with sufficient buoyancy to support the bridge and dynamic loads.
While pontoon bridges are usually temporary structures, some are used for long periods of time.
Permanent floating bridges are useful for traversing features lacking strong bedrock for traditional piers.
Such bridges can require a section that is elevated, or can be raised or removed, to allow ships to pass.
Types of Types of BridgesBridges
Floating BridgeFloating Bridge
Bridge is the KEY ELEMENTin a Transportation System
What is a Bridge?
Structures for Transportation
Beauty can be expressed in the
structural efficiency, simplicity, and
repetition of a bridge.
Mayur Viaduct, France
SubstructureFoundation (Pile/Spread footing)Pier (Column)Abutment
SuperstructureAny structure above bearingWearing surface
Bridge Components
Bridge Components
Bridge Planning
Traffic StudiesHydro technical StudiesGeotechnical StudiesEnvironmental ConsiderationsAlternatives for Bridge TypeEconomic Feasibility Bridge Selection and Detailed Design
Span>6m BridgeSpan100m
Bridge Span Length
Steel Concrete Timber Hybrid Stone/Brick FRP
Pedestrian Highway Railroad
Short Medium Long
Slab Girder Truss Arch Suspension Cable-Stayed
MaterialMaterial
UsageUsage
Span
Structural form
Types of Bridges
Material and FabricationMaterialsMasonry (brick, rock)
Timber
Reinforced Concrete
Prestressed Concrete
Iron
Steel
Composites
FabricationPrecast (RC, PC)
Cast in place (RC, PC)
Pre tensioned (PC)
Post tensioned (PC)
Prefabricated (Steel)
Rivet (steel)
Bolted (steel, timber)
Types of Bridges
Basic types based on structural form:
ArchBeamCantileverTrussCable StayedSuspension
Types of Bridges
Types of Bridges
Arch BridgeArch bridges are one of the oldest types of
bridges and have great natural strength. Instead of pushing straight down, the weight
of an arch bridge is carried outward along the curve of the arch to the supports at each end.
These supports, called the abutments, carry the load and keep the ends of the bridge from spreading out.
Forces
When something pushes down on the beam, the beam bends. Its top edge is pushed together, and its bottom edge is pulled apart.
Beam/Girder BridgeThe most basic type of bridge
Typically consists of a beam simplysupported on each side by a support andcan be made continuous later
Typically inexpensive to build
Types of Bridges
Beam/Girder BridgeCurrently, most of the beam bridgesare precast (in case of RC and PC) orprefabricated
Most are simply-supported
Some are made continuous on site
Simply supported
Cantilever
Continuous
Types of Bridges
Cantilever BridgeIn a cantilever bridge, the roadway isconstructed out from the pier in twodirections at the same time so that theweight on both sides counterbalanceeach other
Notice the larger section at thesupport to resist the negative moments
Firth of Forth Bridge, Scotland521m span
Types of Bridges
Truss BridgeAll beams in a truss bridge are straight.Trusses are comprised of many small beamsthat together can support a large amount ofweight and span great distances.
Typical Span lengths: 40m-500m
Types of Bridges
Suspension bridge needs to have very strong main cables
Cables are anchored at the abutment
Suspension Bridges
London Tower Bridge (1894),UK
Types of Bridges
Types of Bridges
Cable-stayed Bridge
All the forces are transferred fromthe deck through the cables to thepylon
Roadway deck can be : (prestressed) Concrete Box Deck Steel Box Deck Steel Truss Deck
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