learning standards 5. construction technologies construction technology involves building structures...

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 7 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 obstacleEx: Roads, Railroad Tracks, Rivers, Valleys etc.It does not have to be water!

Parts of a Bridge

Surface on which traffic moves

Deck

Heavy supports at the end of a bridgeAbutments

PierHeavy column that holds up a bridge

Tower

Heavy column above the bridge that supports cables

Span

Distance between 2 supports or towers – Used to describe the length of the bridge

Thick wire that supports the deck of the bridge Cables

Triangular framework used to support the deck of the bridge

Truss

Stepping Stones

Early Bridges

Logs Over Streams

The first bridges were:

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 to a structure when something heavy crosses over it

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 are under COMPRESSION

Forces Impacting Beam Bridges (Forces)

Bottom of Beam Bridges are under TENSION

Drawbridge

Also known as a Bascule BridgeA Beam Bridge that has surfaces that can be raised & lowered to allow the passage of boats

Arch Bridge

Arch Bridges were first designed & created by the Romans

Arch bridges typically span distances of 200 – 800 feet (can span longer distances)

Arch Bridge

Arch bridges distribute weight sideways & down around the curve

Arch bridges rely on the force of compression to work effectively

First Arch Bridges were made of wedge shaped stones locked in a curve. The stones were locked in place by a Keystone

Used to cross very wide spans (2000 - 7000 ft)

Suspension BridgeBridge is suspended (hangs) from large vertical cables

Forces Impacting Suspension Bridges

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 (deck)

Cheaper & easier to construct than traditional Suspension Bridges

Typically span distances of 500 – 2800 feet (can be longer)

Forces Impacting Cable Stayed

BridgesCables are under the force of tension

Towers are under the force of compression

Truss Bridge

Made of steel beams constructed into rigid triangle shapes called trusses

Triangles are considered to be the strongest self supporting shape

The trusses can be above or below the bridge

Forces Impacting Truss Bridges

Blue Arrows represent

Red Arrows represent

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 BridgeCantilever Bridge (using

trusses)

5780 ft long

Opened in 1965

Washington Bridge - Providence, RI

Opened 9/25/1930

Arch Bridge consisting of a series of arches

Glen Canyon Bridge & Dam

Lake Powell, Az

Crosses Colorado River

Opened in 1966

1560 ft long

Steel Arch Bridge

Eads Bridge

Crosses the Mississippi River - Connects St. Louis, Missouri & East St. Louis, Illinois

1st major all steel bridge

Built in 1874

Brooklyn Bridge

Opened May 24, 1883 – it took 13 years to build

Crosses East River in New York City

Connects 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

Spans the valley of the River Tarn near Millau, France

Tallest bridge in the world – one of the masts has a summit of 1,125 ft

Taller than the Eiffel Tower & just shorter (125 ft) than the Empire State Building

Opened December 14, 2004 (ahead of schedule) – work began in October 2001

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

IWay Video Part 1

IWay Video Part 2

Cape Cod Railroad Bridge

Lift BridgeCrosses Cape Cod Canal in Bourne, Ma

Opened in 1935

Chesapeake Bay Bridge-Tunnel

Continuous Span & Truss Bridge

with Tunnels

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.

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