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]
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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
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