Name



Name ________________________________________ Page________

Building Big “Bridges” PBS



Types of Bridges

The beam bridge...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 250 feet.

Beam Bridge: Forces

When something pushes down on the beam, the beam bends. Its top edge is pushed together, and its bottom edge is pulled apart.

[pic][pic]

The Truss bridge...consists of an assembly of triangles. Truss bridges are commonly made from a series of straight, steel bars. The Firth of Forth Bridge in Scotland is a cantilever bridge, a complex version of the truss bridge. Rigid arms extend from both sides of two piers. Diagonal steel tubes, projecting from the top and bottom of each pier, hold the arms in place. The arms that project toward the middle are only supported on one side, like really strong diving boards. These "diving boards," called cantilever arms, support a third, central span.

Truss Bridge: Forces

Every bar in this cantilever bridge experiences either a pushing or pulling force. The bars rarely bend. This is why cantilever bridges can span farther than beam bridges.

[pic] [pic] Firth of Forth Bridge

Truss Design

Scotland

The Arch bridge...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 Bridge: 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.

[pic] [pic] Ancient Roman Aqueduct

The Suspension bridge… can span 2,000 to 7,000 feet – way farther than any other type of bridge! Most suspension bridges have a truss system beneath the roadway to resist bending and twisting.

Suspension Bridge: 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.

[pic] [pic]

Name ________________________________________ Page________

Bridge TERMS

Brainstorming - A group idea-gathering techniques based on the concept that a large quantity of ideas will help solve a problem

Beam - a rigid, usually horizontal, structural element

Beam Bridge - a simple type of bridge, composed of horizontal beams supported by vertical posts

Bend - (v.) to curve; bending occurs when a straight material becomes curved; one side squeezes together in compression, and the other side stretches apart in tension

Cantilever - a projecting structure supported only at one end, like a shelf bracket or a diving board

Capital - a resource in the form of a commodity or currency (money) having value which can be used in exchange for other resources.

Compression - a pressing force that squeezes a material together

Concrete -a mixture of water, sand, small stones, and a gray powder called cement

Engineering -a profession in which a knowledge of math and natural science is applied to develop ways to utilize the materials and forces of nature for the benefit of all human being

Force - any action that tends to maintain or alter the position of a structure

Limitations - Constraints imposed by scientific principles or limited resources are called

Load - weight distribution throughout a structure; loads caused by wind, earthquakes, and gravity, for example, affect how weight is distributed throughout a structure

Shear - a force that causes parts of a material to slide past one another in opposite directions

Span -(n.) the distance a bridge extends between two supports; (v.) to traverse a specific distance

Steel - an alloy of iron and carbon that is hard, strong, and malleable

Stable -(adj.) ability to resist collapse and deformation; stability (n.) characteristic of a structure that is able to carry a realistic load without collapsing or deforming significantly

Structural Engineer -an engineer who investigates the behavior and design of all kinds of structures, including dams, domes, tunnels, bridges, and skyscrapers, to make sure they are safe and sound for human use

Tension - a stretching force that pulls on a material

Torsion -an action that twists a material

Tower - the vertical structure in a suspension bridge or cable-stayed bridge from which cables are hung; also used loosely as a synonym for the term skyscraper

Sub For Mr. Darling

3/1/01

Room 202

Technology

Period 1-2

7th grade block see attached sheet for details

7:58-9:21

Room 202

Period 3

8th grade Technology

9:24-10:04

Room 202

Show “Building Big Dams”

Record the number or spot you left off at for Friday’s class

Period 4

8th grade Technology

10:07-10:47

Room 202

Show “Building Big Dams”

Record the number or spot you left off at for Friday’s class

I should be back for the start of this 5 and 6th period class

Period 5-6

7th grade block see attached sheet for details

10:50-11:30

Room 202

Same plans as period 1-2

Sub For Mr. Darling

Technology 7I

Period 1-2 Block

7:58-9:21

Show Video “Building Big Bridges”

After the bridge video about 55 minutes long

Ask questions for tech Money $$$$$$ each question is worth $50

After questions hand out page # 20 Types of Bridges and bridge terms

For questions see Bridge terms sheet - give the definition and ask for the term. Use the ones I have starred or others.

Other questions from the video include: (or use any others you can think of)

4 Questions for 4 different people

Name 1 type of bridge

Answer: Beam, Arch, Suspension, Truss

1. What type of bridges did Romans build

Answer: Arch

2. What is the stone at the top of an arch called

Answer: key stone Make a drawing on the board

3. Why did the Toccoma Narrows bridge collapse?

Answer: Solid road surface wind would get caught and twist the bridge Make a drawing

Answer: self excited vibration.

4. What bridge connected Manhattan and Brooklyn and what type was it?

Answer: Brooklyn Bridge

5. What is the device called to borrow below the river bottom so that the towers of a suspension bridge sit on solid ground.

Answer: Cason

6. The problem with stone bridges included: (3 answers / 3 questions)

Answer: heavy, expensive, hard to build

7. The first Iron Bridge was built in this Country

Answer: England

8. 1770 Smelting coal helped create cast iron. Pieces could be molded in sand from molten metal.. Machinery, Tools, and bridge pieces could be fabricated and assembled later. This is the beginning of this monumental time period.

Answer: This was the basis of the Industrial Revolution

9. Iron Bridges failed because:

Answer: Trains were too heavy and the iron cracked and failed

10. Gustav Eiffel created the

Answer: Wrought iron arch and Eiffel tower

11. Huge suspension bridge in San Francisco is the

Answer: Golden Gate

12. The Golden Gate is painted this color

Answer: International Orange

13. Aesthetics refers to

Answer: The beauty or artistic design of something. Pleasing to the eye.

14. The Golden Gate had to be built to withstand:

Answers: High wind, tide, earthquakes,

Name ________________________________________ Page________

Bridge QUESTIONS

Romans constructed their bridges out of stone

And used arch

Stone keystone

Disadvantages Heavy, long time to build

Wanted lighted , stronger, longer spans cheaper

England Iron Bridge Smelting coal

Blast furnaces molten iron into casts “Cast Iron”

Produce large pieces

Instead of constructing bridge they fabricated pre made pieces

As strong as stone but cheaper to build with

Iron was the reason for the Industrial Revolution because people made machinery out of it and iron horses trains but heavy so problems for build builders. problem iron cracked bridges failed

Heavy weight of train strecched an split apart surface crack on cast iron

Inability of cast iron to withstand tension

Other metal wrought iron and steel could withstand more tension

Eiffel Wrought iron arch open framed arch lets wind blow through the wind used a truss configuration to elimanate unneeded materials. Bridge in ???? Bridge under compression and tension.

Firth of Fourth bridge in Scotland Cantilevar 1890 1st bridge built of primarliy steel Cantelevar design

How to build a large bridge without breaking the bank

Long spans

1st Suspended BridgeBristol England 1830 road way held from above rather than beneath Cable attached to towers and anchroges

NY Brooklyn Bridge connecting Manhatten and Brooklyn over the east river. Roebling died

Span farther and towers rest in water

Tower foundation to rest on solid rock far below the muddy bottom of the east river Cason

1869 Washington roebling took over

Cason wooden box compressed air pumped in created an airlock

Finished in 1883 14 years after beginning Towers were the tallest structure in America

Working in Cason dangerous dim light Benz come out of compressed air slowly it creates air bubles in blood stream and severe pain in the joints.

San Fransicso Cross the Golden Gate the Gateway to the Pacific Ocean

Bridge needed to withstand wind, tide, Fog, earthquakes

Straus designer Needed to be aesthetic

Tradeoffs

Tacoma Narrow bridge : wind braceing solid road base.

Forces that act on a bridge include: Load live and dead, wind

1. The first Dam built was in ancient ____________

1.

2. The worlds largest hydroelectric dam should be finished being built in the year 2009 in this country?

1. USA

2. Japan

3. Brazil

4. China

3. This gravity dam in Nevada did not have to be curved but the engineers thought that the people would feel safer with the curved design.

1. Aswan High Dam

2. Grand Coulee Dam

3. Itaipu Dam

4. Hoover Dam

5. Environmentally impacts that may be affected when you build a dam include.

1. migration of people

2. migration of animals

3. submergence of villages

4. all of the above

6. Alternative power sources to building dams include

1. coal

2. nuclear

3. solar

4. all of the above

6. Limitations imposed by scientific principles or limited resources are called

1. tradeoffs

2. optimization

3. criteria

4. constraints

7. Matching technology to human needs and characteristics is known as

1. aesthetics

2. ergonomics

3. constraints

4. optimization

8. The process of obtaining the solution that best satisfies all the criteria within the established constraints or limitations is

1. ergonomics

2. optimization

3. aesthetics

4. brainstorming

9. When people design large structures they often have a Sensitivity to art and beauty. This is known as

1. aesthetics

2. assessment

3. design

4. expertise

10. The process or end result of reaching a workable compromise is known as

1. Value

2. Symbiotic

3. trade off

4. criteria

11. The amount of Capital to build this dam was $18 billion

1. Three Gorge Dam

2. Grand Coulee Dam

3. Itaipu Dam

4. Hoover Dam

12. A bypass created to divert water around a dam so that construction can take place is known as

1. diversion channel

2. spillway

3. masonry

4. pressure

Name ________________________________________ Page________

Bridge Crossword

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download