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Bridges. 5. Construction Technologies - PowerPoint PPT Presentation
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Learning Standards5. Construction Technologies
Construction technology involves building structures in order to contain, shelter, manufacture, transport, communicate, and provide recreation.
5.2 Identify and describe three major types of bridges (e.g., arch, beam, and suspension) and their appropriate uses (e.g., site, span, resources, and load).
5.3 Explain how the forces of tension, compression, torsion, bending, and shear affect the performance of bridges.
5.4 Describe and explain the effects of loads and structural shapes on bridges.
Learning Objectives
1)Define Bridge
2) Identify & describe 5 major parts of a bridge
3) Identify & describe 5 forces that affect bridges
4) Identify & describe 7 types of bridges
At the conclusion of the lesson students will beable to:
A structure built to span a physical obstacle
Parts of a Bridge
Surface on which traffic moves
Deck
Heavy supports at the end of a bridge
AbutmentsPier
Heavy column that holds up a bridge
Tower
Heavy column above the bridge that supports cables
Span
Distance between 2 supports or towers
Thick wire that supports the deck of the bridge
Cables
Parts of a Bridge
Triangular framework used to support the bridge
Truss
Stepping Stones
Early Bridges
Log Over a Stream
The first bridges were:
Early Bridges
Later people used large flat rocks connect the stepping stones allowing them to cross over the bridge with small carts
Forces Upon Bridges
A force that pushesCompression
A force that pullsTension
A force that twists
A force acting across any structureShear
What happens when something heavy crosses a structure
Bending
Forces must be considered when building bridges
Torsion
Click here to learn more about the forces that affect bridges
Most common & oldest type of bridgeExample: Highway overpasses
Beam Bridge
Longer Beam Bridges need piers for support along the span
Beam BridgeUnsupported beams can span distances only up to 250 feet
Top of Beam Bridges & piers are under COMPRESSION
Beam Bridge
Bottom of Beam Bridges are under TENSION
Drawbridge
A Beam Bridge that has surfaces that can be raised or lowered to allow the passage of boats
Arch Bridge
First Arch Bridges were made of wedge shaped stones locked in a curve
First designed & created by the Romans
Arch Bridge
Arch bridges rely on the force of compression to work effectively
Used to cross very wide spans (2000 - 7000 ft)
Suspension BridgeBridge is suspended (hangs) from large vertical cables
Suspension Bridge
Cables & abutments (anchorages) are under the force of tension
Towers are under the force of compression
Cable Stayed Bridge
Cables connected to towers stretch down diagonally to support beam
Cheaper & easier to construct than traditional Suspension Bridge
Cable Stayed Bridge
Cables are under the force of tensionTowers are under the force of compression
Truss Bridge
Made of steel beams constructed into rigid triangle shapes called trusses
Triangles are considered one of the strongest shapes
Why triangles???
The trusses can be above or below the bridge
Truss Bridge
Blue Arrows represent
Red Arrows represent
Forces affecting Truss Bridges
TENSION
COMPRESSION
Cantilever Bridge (using trusses)
Cantilever: Self supporting beam that is fastened to the ground at one end2 cantilevers meet in the middle & are connected by trusses
The strong design of these bridges resist high winds
Types of Bridges
Types of BridgesArch Bridge
SuspensionBridge
Truss Bridge
Drawbridge
Cable StayedBridge
CantileverBridge
Beam Bridge
Braga Bridge
Cantilever Bridge (using trusses)
5780 ft long
Opened in 1965
Glen Canyon Bridge & Dam
Lake Powell, Az
Crosses Colorado River
Opened in 1966
1560 ft long
Steel Arch Bridge
Brooklyn Bridge
Opened May 24, 1883 – it took 13 years to build
Crosses East River in New York CityConnects Manhattan & Brooklyn
Longest Suspension Bridge in the world when it was built5989 Feet
Golden Gate Bridge
Opened May 27, 1937
Crosses SF Bay
Connects SF & Marin County
Longest Suspension Bridge in the world when it was built8981 Feet
Akashi Kaikyo BridgeOpenedApril 5, 1998
12,831 Feet Center Span 6,532 Feet
Connects Kobe & Awaji IslandAlso known as the Pearl Bridge
Currently the world’s longest Suspension Bridge
Built to withstand 178 MPH winds, earthquakes measuring 8.5 on the Richter Scale & harsh sea currents
Opened October 24, 1929
Crosses Mt. Hope Bay
6,130 Feet Center Span 1,200 Feet
Connects Bristol & Portsmouth Rhode Island
Mt. Hope Bridge
Suspension Bridge
Claiborne Pell Newport Bridge
Crosses the Narragansett Bay – Connects Newport &
Jamestown
Suspension Bridge
Leonard P. Zakim Bunker Hill Memorial Bridge
Crosses the Charles River
Opened in 2003
1432 feet long
Widest Cable Stayed Bridge in the world: 183 feet wide
Millau Viaduct
Millau Viaduct
Located in France
Tallest bridge in the world – one of the masts has a summit of 1,125 ft
Just about as tall as the Empire State Building
Opened December 14, 2004 – Took only 3 years to build
Total length: 8,071 ft
Millau Viaduct
Veterans Memorial BridgeSomerset, Mass.
London Tower Bridge
Drawbridge with Suspension
Providence RiverRailroad Bridge
Drawbridge
Bourne Bridge Arch Bridge (w/ suspended deck)
Crosses Cape Cod Canal in Bourne,
Ma
Opened in 1935Sagamore Bridge
Crosses Cape Cod Canal in
Sagamore, Ma
Opened in 1935
IWay Bridge – Providence, RI
IWay Video Part 1
IWay Video Part 2
Cape Cod Railroad Bridge
Lift BridgeCrosses Cape Cod Canal in Bourne, Ma
Opened in 1935
MCAS Question
Which of the following bridges is an example of a Suspension Bridge?
C. 73%
A. B. C. D.
MCAS QuestionA Beam Bridge supporting a toy truck is shown in the diagram below.
When an object pushes down on this bridge, the bottom edge experiences a force that tends to pull it apart as shown. What is the type of force labeled X?
A. Compression B. ShearC. Tension D. TorsionC. Tension 52%
MCAS QuestionSupport cables in a Suspension Bridge are most stressed by which of the following forces?
A. ShearB. TorsionC. TensionD. Compression
C. Tension 74%
MCAS QuestionAn engineer designing a Suspension Bridge discovers it will need to carry twice the load that was originally estimated. One change the engineer must make to the original design to maintain safety is to increase the
A. length of the wires in tensionB. diameter of the wires in tensionC. height of the support towersD. length of the bridgeB. diameter of the wires in tension
57%
MCAS QuestionThe diagram below shows the supports of a proposed bridge. Which of the following wooden bridge designs, if built from one support to the other would withstand the heaviest load?
D. 87%
B.A. C. D.
MCAS QuestionSeveral students are entering a bridge building contest that requires ice cream sticks & glue to construct the strongest bridge possible. The bridges must be 5 in. wide & span a length of 18 in. Which of the following tests is the most accurate way to determine the strongest span design of these bridges?
A. Roll toy cars across each bridge until it collapsesB. Place concrete construction blocks on top of each bridge until it collapsesC. Stack coins on both ends of each bridge until it collapsesD. Place D Cell batteries at the center of each bridge until it collapses
D. 47%
MCAS Question
a. Identify 1 example from the figure that represents a type of Arch Bridgeb. Explain how an Arch Bridge is different from a Beam Bridgec. Identify 1 example from the figure that represents a type of Beam Bridged. Explain how a Beam Bridge is different from a Suspension Bridge
The figure below shows examples of bridge numbered 1 through 6.
Scoring GuideScore Point 4
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